SDMS DocID 2104487

Exponent Boulder Laboratory: Quality Assurance Plan

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Title and Approval Page

Exponent Boulder Laboratory

Name of Laboratory

4699 Nautilus Court South, #203 Boulder, Colorado 80301

(303)527-1324

Address and Telephone Number

27 September 2000

Day/Month/Year

Laboratory Director:

Name

Laboratory QA Officer:

Name

Mgnature ^

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E^ponenr

Exponent Boulder Laboratory: Quality Assurance Plan

Prepared by

Exponent 4940 Pearl East Circle, Suite 300 Boulder, Colorado 80301

September 2000

Doc. No.: 8600A20.002 0701 0900 RN40

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Contents

Page

Organization and Management 1

Al Quality Policy 1

A2 Project Organization and Responsibility 1

Laboratory Facilities 4

Bl Accommodation and Environment 4

B2 Equipment 4

Measurement /Data Acquisition 5

CI Sample Handling and Custody Requirements 5

C2 Common Laboratory Methods 5

C3 Quality Objectives and Criteria for Measurement Data 5

C4 Quality Control Requirements 5

C5 Instrument/Equipment Maintenance Requirements 6

C6 Instmment Calibration and Frequency 6

C7 Data Management 7

Assessment and Oversight 10

Dl Performance and System Audits 10

Data Review and Usability 11

El Review Of Laboratory Results 11

E2 Data Validation 11

E3 Reconciliation with User Requirements 11

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Attachment 1 - Project Organization

Attachment 2 - Sample Handling and Custody

Attachment 3 - Standard Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock

Attachment 4 - Standard Methods for the Examination of Water and Wastewater

Attachment 5 - Standard Test Methods for pH of Water

Attachment 6 - Calibration SOPs

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Organization and Management

A1 Quality Policy

Exponent is committed to satisfying clients by providing superior services and products, ensured through a rigorous quality management system that is integral to our business strategy. All employees are required to be familiar with the system, comply with it, and continually strive to achieve its intent in all aspects of work. Based on the intended application of the work, appropriately stringent verification is implemented for all work products. Exponent's Quality Management System (QMS) is applicable to all professional consulting services, and it complies with the ISO 9001:1994 standard and U.S. Code of Federal Regulations, Title 10, Volume 1, Chapter L Part 50, Appendix B, 1-1-98 Edition.

A2 Project Organization and Responsibility

Exponent's Quality Management System:

• Is integrated across the organization

• Addresses a variety of business needs

• Fits with our culture of being committed to highest quality

• Allows flexibility in its procedural requirements

• Effectively achieves quality goals.

Exponent's QMS is based on the premise that Exponent personnel are capable of performing their jobs at the highest level and are motivated to do the right thing. Quality expectations are set top-down by the leadership, and ownership for creating quality is taken bottom-up. In addition, the system contains a number of checks and balances to ensure that no work product leaves Exponent without being subjected to rigorous review.

Client services at Exponent are organized in projects. A Project Manager is responsible for the overall project coordination and implementation. Each project also has a Project Advisor, who provides appropriate and timely guidance to the Project Manager on project activities and client relations. Typically, the Project Advisor is a principal or senior staff member with special expertise in the technical practice areas of the project. Work products are quality assured on an ongoing basis through peer reviews of work approach or methodology, and rigorous verification of results. In addition, all external written communications are subjected to separate technical, editorial, and corporate reviews.

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The Exponent QMS includes an independent Quality Manager (corporate person who does not work at EBL) who is trained as an internal quality auditor and audits groups for compliance with Exponent QMS. Audit results are incorporated into the performance review process, which includes explicitly defined quality performance criteria. The organization of staff under the QMS system is detailed in Attachment 1.

The Exponent Boulder Laboratory (EBL) organization (not detailed in Attachment 1) includes a laboratory director (Larry Peterson, B.S. Chemistry, M.S. Geochemistry, with 15 years experience) and a lab staff member (Suly Liu, B.S. Chemical Engineering, with 3 years experience). In addition to the laboratory staff member, other Exponent staff members participate in or oversee lab experiments, depending on the complexity or data quality objectives of the project. These staff members include Todd Martin, P.E. (B.S. Civil Engineering, M.S. Environmental Engineering, with 7 years experience), Mike Martin (B.S. Engineering/Civil specialty, M.S. Environmental Engineering, with 8 years experience), and David Atkins (B.S. Physics and Mathematics, M.S. Physics, M.S. Water Resources and Engineering, with 14 years experience).

Work performed in the EBL is overseen by the laboratory director, who also serves as the laboratory quality assurance officer. In addition, the laboratory director serves as the health and safety manager and performs periodic quality and health and safety audits. These audits are in addition to the internal QMS audits performed by the Quality Manager (Attachment 1). Once an experiment is complete, all of the data and lab documentation flows into the rigorous QMS program outlined in Attachment 1. During the course of performing project tests at EBL, the Laboratory Director reports directly to the Project Manager, who is responsible for reviewing the overall quality of laboratory experiments. Everyone within Exponent is responsible for maintaining and improving the quality of the experiments performed at the EBL. A listing of responsibilities is provided below:

• Laboratory Director - Provides leadership and technical expertise in support of lab experiments. Oversees administrative functions of the laboratory, including staffing, allocation of supplies, and scheduling. The laboratory director also ensures that the internal lab QA program and the QMS are implemented in the laboratory, reviews and approves changes to this document, and reviews and approves Standard Operating Procedures (SOPs) and other methods used at the lab. The laboratory manager also serves as the laboratory quality assurance officer and the health and safety manager.

Laboratory Quality Assurance Officer (LQAO) - Oversees implementation of the quality program and performs periodic audits to ensure compliance with the QC procedures. The LQAO also works with project managers and office staff to develop appropriate quality control objectives, and to select appropriate quality control samples on individual projects requiring experimental work at the EBL. The LQAO is responsible for reviewing this manual and updating it as needed annually. Responsibilities also include maintaining quality

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•

control (QC) records, such as laboratory notebooks and calibration results, reviewing laboratory QC results, and recommending corrective action for unacceptable experimental results to project managers. In the absence of the laboratory director, all of these responsibilities fall on the project manager who is using the EBL to conduct experiments.

Health and Safety Manager - Responsible for administrating health and safety (H&S) policies at the EBL, including the development of general safety procedures, maintenance of the lab chemical hygiene plan, monitoring of hazardous waste disposal, investigation of incidents, and performing periodic audits to ensure compliance with H&S policies. The H&S manager is also responsible for the review and approval of experiment-specific H&S procedures developed by project managers and staff.

Laboratory Staff - Responsible for ensuring that the lab experiments are performed correctly, are documented properly, and are in compliance with project-specific requirements. This entails reviewing project-specific requirements (procedures, QC, and H&S) and following up with project staff to ensure that the requirements are understood. Laboratory staff members are also responsible for maintaining sample custody documentation for all samples, from receipt through disposal.

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Laboratory Facilities

Bl Accommodation and Environment

The EBL is a 1,700-square-foot facility that is divided into areas for sample preparation, laboratory work, sample storage, administrative/records, and equipment storage. A floor plan for EBL is provided as Figure 1. Good housekeeping and facilities maintenance are performed to limit contamination sources within the laboratory. The lab area includes a double-wide fume hood for performing experiments, and a dust hood for sieving and handling dry samples. The EBL is a separate facility from the Boulder Exponent office. Access to the facility is restricted to the laboratory manager and staff, along with certain key project staff who oversee experiments. In addition, access to the sample storage area and the sample custody/lab logbooks is restricted to the laboratory manager and staff Copies of all lab logbooks and custody documentation are provided to project managers and staff for review purposes.

B2 Equipment

The EBL contains a large amount of general laboratory equipment—including glassware, sieves, centrifuge, filter apparatus, pipettes, etc.—that does not require calibration or QC procedures for use. A list of specific equipment that requires calibration is provided in Table 1. All laboratory equipment is maintained by EBL staff. Any equipment that is damaged or fails during the process of calibradon is removed from the lab area and labeled as broken. All malfunctioning equipment that cannot be repaired by the lab staff (i.e., scales and meters) is submitted to the manufacturer for repair or servicing. Records of the work performed on equipment are kept in the laboratory manager's files.

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IVIeasurement /Data Acquisition

CI Sample Handling and Custody Requirements

Procedures for sample handling and the control and maintenance of documents are described in the Exponent Boulder Laboratory Sample Handling and Custody Procedures (Attachment 2). This document covers procedures for completing chain-of-custody/sample analysis request (COC/SAR) forms, and for distribudon and filing of all sample custody documents. All samples and hazardous waste generated from . experiments are disposed of by shipping the material back to the client or site for onsite disposal, or through a hazardous waste contractor (Laidlaw).

C2 Common Laboratory Methods

EBL staff members routinely perform measurements of moisture content, acidity, and alkalinity during project experiments. Moisture content is performed using American Society for Testing and Materials (ASTM) Method D2216-92 (Attachment 3). Acidity and alkalinity titrations are performed using Standard Methods for the Examination of Water and Wastewater (SMEWW), SM 2310 and SM 2320, respectively. These methods are included as Attachment 4. Measurement of pH is performed according to ASTM Method D 1293-95 (see Attachment 5).

C3 Quality Objectives and Criteria for Measurement Data

Measurement quality objectives are typically assessed by evaluating precision, accuracy, representativeness, completeness, and comparability. Due to the qualitative nature and the large variety of experiments performed in the EBL, it is not possible to provide specific data quality objectives (DQOs) in this document. DQOs are developed on a project-specific basis and are usually documented in laboratory test plans and field sampling plans. If criteria for acceptability of QC sample results are not specified in the guidance for a particular experiment, the EBL uses 20 percent for precision (duplicates), 75-125 percent for bias (spike recovery), and 90 percent for completeness.

For ASTM and SMEWW methods, the EBL uses the criteria specified in the individual methods for evaluating measurement quality.

C4 Quality Control Requirements

Quality control samples are commonly included as part of laboratory experiments and include duplicates, blanks, matrix spikes, and standard reference materials. Due to the variety of matrices tested in the lab, the complexity of many experiments, and the variety

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of experimental DQOs, the number and frequency of QC samples are determined on a project-specific basis. If quantitative data are being collected as part of a lab experiment and control limits are not specified in project documents, then the EBL uses the following criteria:

• Method Blanks - Results less than the method reporting limit

• Duplicates - Relative percent difference (RPD) <20 percent

• Matrix spikes - 75-125 percent recovery

• Standard reference materials - 75-125 percent of true value.

When QC limits are not met, the QC data are reviewed by the laboratory manager and project manager in light of the overall experimental results. The corrective action required depends on the results of this analysis. If the QC data indicate that the experimental data are compromised, the corrective action is to repeat the experiment. If the QC data indicate a slight bias high or low that can be incorporated into the experimental conclusions, the data may be qualified as estimated and used. If the QC data are believed to have a minimal impact on the overall results (e.g., an analyte detected in a blank at 0.5 ppm, but detected in all samples at 500 ppm or greater), then no corrective action would be taken. All QC data will be presented and discussed in the project report.

C5 Instrument/Equipment Maintenance Requirements

All laboratory equipment is maintained according to the manufacturer's operating manual. A record of all equipment maintenance is stored in the laboratory manager's files. When the equipment is damaged or fails calibration specifications, the item is removed form the lab area and labeled as broken. If the instrument or piece of equipment cannot be fixed by EBL staff (with input from the manufacturer), then it is shipped to the manufacturer or qualified equipment service company for repair. If the equipment is beyond repair, the item is disposed of and a replacement is purchased.

C6 Instrument Calibration and Frequency

Instruments commonly used by EBL that require calibration are pH meters, a specific conductance meter, and laboratory scales. Instructions for calibrating these items are provided in Attachments 5 and 6 and include:

• ASTM Method D1293-95 - Standard Test Method for pH of Water, Test Method B (Attachment 5)

SOP 87 - Calibrating the Specific Conductance Meter (Atachment 6)

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• SOP EBLl - Boulder Laboratory Balance Calibration SOP (Version 1). (Attachment 6)

SOP 87 covers the calibration of specific conductance meters that have a probe that automatically corrects readings to 25 °C and for which the meter/probe conductance readings cannot be adjusted manually. The Orion Model 124 specific conductance meter used at EBL falls into this category of meter.

The frequency and documentation procedures for the lab scales are presented in SOP EBLl. The pH and specific conductance meters are calibrated prior to performing measurements on each group of samples. The specific conductance meter is calibrated once per day if it is in continuous service. The pH meter is calibrated a minimum of twice daily if it is in continuous service. The frequency may be increased depending on the sample matrix being measured if it is observed that the matrix is fouling the electrode. This is evaluated by measuring the pH-7.0 buffer periodically throughout the day. If the pH value falls outside of the range 6.90-7.10, then the meter must be recalibrated. All meter calibradons are recorded in the laboratory notebook for the specific project that is being conducted. If the meters cannot be calibrated, then Section C5 should be consulted.

C7 Data Management

1.0 Laboratory Records

All laboratory records (calibrations/laboratory test methods/logbooks) are kept for a period of three years, unless different project-specific requirements are stated by the project manager. All records are reported accurately and clearly in bound laboratory notebooks. If errors are made in the laboratory notebooks, they are corrected, and a single line is drawn through the error. The correction is then initialed and dated by the lab staff member. If procedures are provided to lab staff, they are referenced in the notebook (i.e., memo or laboratory testing plan). At a minimum, the laboratory notebook must contain the following:

• Project and contract number

• Procedures or a reference to procedures

• Lab staff member's signature

• Date of experiment

• Reference to equipment and chemicals used

• Results of all calibrations

• Times noted for steps throughout the experiment

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• Description of sample handling and preparation

• Observations

• Results of all measurements

• A listing of all samples collected and shipped to outside laboratories

• Identification of any quality control requirements

• Information regarding photographic or video documentation.

1.2 Standard Operating Procedures (SOPs)

All relevant Exponent standard operating procedures (SOPs) are provided in Attachments 2 through 6 except for Equipment Decontamination. The following decontamination procedure is used by EBL for laboratory glassware and pans:

1. Tap-water rinse

2. Liquinox wash

3. Tap-water rinse

4. 10 percent (v/v) nitric acid rinse (metals only)

5. Acetone rinse (organics only)

6. Hexane rinse (organics only)

7. Deionized water rinse

8. Air dry.

1.3 EBL Laboratory Data Deliverable Requirements

At a minimum, the EBL data deliverable packages provided to the Exponent project manager will include the following:

• Experimental documentation (copies of the logbook)

• Chain-of-custody forms for samples sent to outside laboratories

• Chain of custody for archived samples

• Summary of waste generated during the experiment.

All EBL data deliverable packages are reviewed by the Exponent project manager or delegate for completeness and quality. If quality issues arise, the EBL quality assurance

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manager will review the deliverable and meet with the Exponent project manager to evaluate the impact and the course for corrective action.

1.4 Data Management

On completion of laboratory experiments at the EBL, the results are delivered to the project manger. From this point forward, all data flow into Exponent's Quality Management System (QMS), as described previously. The QMS includes multiple QC checks to assess data quality, and documentation of those checks. The first step is to review all calculations and then enter the laboratory data into Excel® spreadsheets. A QC check of data entry is performed before the data are evaluated or reported, and the final approved spreadsheet is placed into a controlled-access data directory. Additional QC checks are conducted and documented if data are tabulated for inclusion in a project report.

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Assessment and Oversight

D1 Performance and System Audits

The laboratory manager performs system and H&S audits at a minimum of every year. System audits may be performed more frequently if data quality issues are identified by project managers during their review of laboratory experiment deliverables. Results of system audits are distributed to project managers and laboratory staff.

If the results of a system audit indicate that corrective actions are needed, then such actions are implemented immediately. If the system audit indicates that the cause of QC problems is inadequate laboratory methods or SOPs, then the laboratory manager will replace these procedures with acceptable ones and train laboratory staff in the use of the new procedures. If the cause is laboratory staff not following written procedures or best laboratory practices, then additional training will be provided to laboratory staff, followed by additional audits to assess the effectiveness of the training.

The internal reviews conducted by senior technical staff as part of Exponent's QMS are designed to ensure that laboratory experiments produce data that meet project DQOs and include adequate numbers of appropriate QC samples. However, if a review of experiment results indicates deficiencies in data quality or numbers of appropriate QC samples, the laboratory manager will work with the project manager to improve the experimental design. Under such a scenario, the laboratory manager would be directly involved in the review process for any future laboratory work associated with this project or project manager.

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Data Review and Usability

E1 Review Of Laboratory Results

All EBL data deliverable packages are reviewed by the Exponent project manager or delegate for completeness and quality. If quality issues arise, the EBL quality assurance manager will review the deliverable and meet with the Exponent project manager to evaluate the impact and course for corrective action.

E2 Data Validation

This section is not applicable to EBL.

E3 Reconciliation with User Requirements

EBL will use all project-specific control criteria to evaluate QC samples that are generated as part of an EBL laboratory experiment. It is the responsibility of the project manager to communicate all project-specific requirements to the laboratory manager before an experiment begins.

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Table 1 . Exponent laboratory equipment l ist

Item Manufacturer Placed in Service Location

3000 XE balance (0-3 kg; accurate to 0.1 g)

100A analytical balance (0-100 g; accurate to 0.0001 g

Balance (0-50 lbs; accurate to 0.01 lbs)

Refrigerator (liquid SRMs)

Refrigerator (sample refrigerator)

Model 250A pH meter

Model 124 conductivity meter

Model 526G drying oven (30-200 °C; accuracy ±3 °C)

4x2.5x2.5 ft end-over-end mixer (30 rpm)

Denver Instrument

Denver Instrument

Detecto

Emerson

Hot Point

Orion

Orion

Fisher Scientific

Exponent

04/91

04/91

05/96

04/91

08/98

09/93

12/87

03/92

06/93

Lab area

Lab area

Sample prep area

Lab area

Sample storage area

Lab area

Lab area

Lab area

Sample prep area

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Attaclimeet 1

Project Orgamzatiom

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rganizatio exponent QMS

2.1 Management*Q"^'"y'*=''*'*^''^*'*p ** •Establish/implement Exponent QMS

R 6 p r 6 S © n t a t i V G * Q " a l ' * y concerns follow-up •iVlanaj^ement review

2.5 Quality Manager * J ^ - i - - < ^ X V ; ? " ^ ^ ^ " ^ ^ •! \ p II III O M s II iiiiiiu

2.7 Quality ' ^ ^ Representatjvec^^ •Coo i i l i i i i i I I I I I I I N \ I II M lip v i

2.8 Recorders cf^Yl •Evidence recd I li ^ \ ' •Subcontractoi f ul Cy'X^\ •Calibration r( iil"" f\ f ^ / • )

2.2 Prefect Advisor f ' . ' / j ^ •Aiitbori/e project

•Approve Project Manager •'I'iniely i^uidance

•^ •Follow up on concerns

: :?

::>

3 2.3 Project IVIaoagei

2.4 Project staff 5; •IVlaintain resumes •Maintain quality of work •Maintain project resources - /4»c««a(jB^p^-A •Keep Project Manager infornie<l UJ^'tn "O

2.6 Business DeveSopment ^ ^ ^ Human Resources

A. - ..^ •/V^5^:;*SSs£S!v 'Client surv. B7*t^i^jW^vS^si'';5l^\\-? •Resume ace

rveys L'cess

" ^ •Offer Letters , ^ "Other HR-related liability issues

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2

Sample HamdMEg aed Custody

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Exponent Boulder Laboratory: Sample Handling And Custody Procedures

The following document oudines the minimum requirements that all Exponent staff are expected to follow, without exception. During the course of project work, a number of situations arise where the custody of samples changes from one company or person to another. Staff must be familiar with a Chain of Custody/Sample Analysis Request (COC/SAR) form and be able to fill it out correctly to maintain sample custody.

COC/SAR FORI\/IS

A COC/SAR form is included in this attachment. This combined form allows the documentation of sample custody and also provides for the requesting of sample analysis. The COC/SAR form requires the following informadon to be provided:

1. Project (Name and Number): The project is the client name and/or site and a number, which is the Exponent contract number. This information is essential for proper filing of the custody documentation by project.

2. Samplers (Signature): As the title indicates, a signature is required in this box (do not print). You only need put one signature in this box if more than one person is collecting samples.

3. Sampling Contact: In general, this should be someone who can answer quesdons about the analytical work being performed on the samples if the laboratory calls. The person in this box can be the field sampler or lab worker, as shown in the "Samplers" box, or another person. K in doubt, put the project manager's name in the box. The phone number on the next line is the phone number of the sampling contact.

4. Ship Samples to: Fill in the name, address, city, state, and zip code of the laboratory, as well as a lab contact on the attn; line.

5. Sample No.: List all sample numbers in this column as they appear on the sample tag. Note that it is not acceptable to list only sample numbers or only tag numbers if a sample tag is on the bag or bottle. Both are required.

6. Tag No.: List the red printed number on the sample tag for all samples. Note that it is not acceptable to list only sample numbers or only tag numbers if a sample tag is on the bag or bottle. Both are required.

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7. Date: This is the date that the sample was generated. It is not acceptable to leave this blank.

8. Time: This is the time (military time) that the sample was generated. It is not acceptable to leave this blank.

9. Sample Matrix: An x should be marked in one of the matrix boxes for each sample. If it is not groundwater, soil, surface water, or sediment an x should be placed in the "other" box and this box should be clarified in writing. For example: Other (waste rock).

10. Analyses Requested: There are six blank boxes in this space for writing in analyses. This section can be completed in one of three ways: 1) provide a description of the required analysis in the box; 2) write detailed information in the remarks column and a reference in the box; or 3) reference a Laboratory Service Order (LSO) for detailed information. The LSO reference is the easiest method, and if used, a copy of the LSO should be placed in the COC/SAR file for each project. Approximately 90 percent of Exponent projects have an LSO (it is how the lab bills Exponent), so request a copy from the project manager if you want to reference it on a COC/SAR. Note: If samples are being archived at EBL, this section should be left blank and an X should be placed in the "archive" box.

11. Remarks: Use this section to communicate information regarding analyses or about the samples.

12. Shipped via: How will the sample be delivered to the desdnation?

13. Condition of samples upon receipt: Fill this box in only if you are receiving the samples.

14. Custody Seal intact: Fill this box in only if receiving samples.

15. Relinquished by: received by: and date/time lines at the bottom of the form: This section is critical to maintaining sample custody and must be completed properly. When transferring custody to a separate organization (lab, CU, client) the signatures must be obtained and the date and time of transfer recorded. If the samples are hand delivered, only one line is necessary. The person that takes the samples from you must sign the form and record the date and time. If you pick up or receive the samples, the person giving you the samples must sign the "relinquished by" line, and you must sign the "received by" line and record the date and time. Each time this occurs, vou need to keep or make a copy for the files, which will be discussed in detail in the following section.

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Filing and Copy Distribution Requirements

COC/SAR Forms

Once the COC/SAR form is complete, it is essential that copies be distributed to the appropriate staff and an original copy is filed in the secured sample custody filing cabinet. The following procedures should be performed every dme a new notation is made on the COC/SAR form. New notations include a change in sample custody, the samples are sieved into two size fractions and split into two jars and the chain is annotated to document the presence of both size fractions, a new form is completed, a correcdon is made on the forms, or the samples are archived into storage.

The COC/SAR form consists of three pages: a white sheet, which always remains with the samples; a yellow sheet, which remains with the samples when they are shipped to the laboratory; and a pink sheet, which is removed prior to shipping to the laboratory or prior to placing the samples into the sample archives. The pink sheet will be the original (file copy) in most cases. If samples are received from the client or other consultant, then the yellow sheet will be the original (file copy). This sheet must be filed in the Sample custody/sample tracking filing cabinet that is located in JaVayne Metzger's office. In addidon, if the samples are stored in the laboratory, a copy needs to be placed in the laboratory filing cabinet. After these two copies are filed, an additional copy must be given to the Project Manager within one day of a new notation, and an additional copy must be given to a task manager if they are directing the experiment or are responsible for tracking the samples. All copies must be stamped with a "COPY" stamp, which are available at the lab, the office front desk, or Larry Peterson's office (upper left desk drawer). The "COPY" stamp is necessary because a copy of a COC/SAR form may need to be used as an original (when only the white form remains or you run out of change-of-custody signature lines). If a copy of the original COC/SAR form is required for the sample custody filing cabinet, this copy must be stamped with the red FILE COPY stamp, which also can be found in the three locadons described above.

Acknowledgment-of-Receipt Faxes

In most cases, when samples are sent to the analytical laboratory, an acknowledgment of receipt is faxed to the office the day the samples are received. This sheet is usually addressed to the sampling contact listed on the COC/SAR form. It is the responsibility of the person receiving this form to review the form for accuracy and to file and distribute copies in the following manner. The original fax gets a red FILE COPY stamp and is filed in the sample custody filing cabinet in J. Metzger's office. A copy is made and stamped with the blue COPY stamp and given to the Project Manager. If a task manager is involved, they also get a blue-stamped copy.

Prior to filing, the Acknowledgment of Receipt shall be checked to make sure that all the samples were received by the laboratory and that the correct analyses were requested. If there is a problem, call the laboratory and note the correcdons and phone conversation on

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the Acknowledgment of Receipt form. In addidon, make corrections to the COC/SAR forms and fax a corrected version to the laboratory. Distribute the corrected forms as indicated above for a new annotation.

Logbook Filing and Distribution of Copies

There are two types of logbooks used at Exponent: field logbooks and laboratory logbooks. The only difference in the filing and copy distribudon procedures is the storage location of the original logbooks. All field logbooks are stored in a locked filing cabinet in Larry Peterson's office, and all laboratory logbooks are stored in a locked filing cabinet in the Boulder laboratory. When needed for copying or correction purposes, logbooks may be checked out for short periods of time and returned to the locked filing cabinet as soon as possible. For detailed instructions on how to properly document work in logbooks, please see Exponent Corporate SOP 4.

The procedures for field and lab logbook filing and copy distribution are as follows. A total of three copies need to be made and distributed each time a new annotadon is made in the logbook. One copy must be stamped with the red FILE COPY stamp and placed in the sample custody/sample documentation filing cabinet in JaVayne Metzger's office. The other two copies must be stamped with the blue COPY stamp and distributed to the Project Manager and Task Manager (and/or Field Sampler). Copies shall be distributed and the files updated every time there is a break in the work. This includes the end of a field collection task (upon return to the office), a break of one day on a lab experiment, or the end of the week on a lab experiment. At this time, the files shall be updated with any new annotations to the logbook, and copies shall be distributed to the Project Manager and Task Manager.

Sample Archiving Procedures

All samples that are stored in the Boulder laboratory shall be archived using the following procedures. A chain-of-custody form must accompany all samples stored in the Boulder laboratory. If the samples are received with a COC form, the samples need to be checked against the form. Sign the "Received by" box of the COC. Also, the date and time (military), sample condition, and custody seal intact boxes need to be filled out on the COC. If the samples are not accompanied by a COC, notify the Lab Manager (Larry Peterson), and the Project Manager to help fill in the details of the samples. The COC form must be completed as specified above. Make an additional four copies of the COC (three if you filled out an Exponent COC for the samples). One copy must be stamped with the FILE COPY stamp, and the others with the COPY stamp. The FILE COPY will accompany the Archive record (described below) and is filed in JaVayne Metzger's office. The pink COC sheet (or second copy stamped FILE COPY) will accompany another archive record form that is placed in the laboratory archive record file. The COPY copies will be distributed to the Project manager and task manager.

Wboulderl \data\projects\a20_front royal\exqapp\sampte handling2.doc

AR301621AR301621

Samples not requiring refrigeradon should be placed in a box (or Ziploc bag), with the COC. The outside of the box should have the following information:

• Project name

• Project number

• Lot number

• Project manager

• Date.

Complete an archive record form, filling in ALL of the information. This form is to be accompanied by a copy of the COC for the samples, and placed in the archive record file in the lab's lockable file cabinet. Another copy of the archive record form should be placed in the "Boulder Laboratory Master Archives List." This is an alphabetical listing of projects that have samples in the laboratory.

Each project will have its own file folder in the locking file cabinet. The folder label will include the project name and number. Three files need to be in this folder:

• Archive record

• Analysis documentation

• Lab logbook copies.

\\boulder1\data\projects\a20_frontroyal\exqapp\sample handling2.doc

AR301622AR301622

CHAIN OF CUSTODY RECORD/SAMPLE ANALYSIS REQUEST FORM Project: (Name and Number)

ExDonent Contact: Office:

Ship to:

Lah Contact/Phnne-

Sample No. Tag No. Date

.'•

Time Matrix

Samplers:

, - ' ' ' ' - • ' J . \y%i^'f^na\ysesJFl&t\upst\d''''\ix'yr^ • • , / >

QQ^gi GW - Groundwater SL-Soll SD-Sediment SW - Surface water

OTHER - Please identify codes

Shipped Qp^HPv/ l lP.q r i f ^n i ' r l e r Othsr

Prior i ty:

U l Normal L J Rush Rush time period

« c a c

5 cs

%

Page of

Exponent" - , Bellevue, WA I (425) 643-9803 (^ Boston, MA ^ (781)466-6681 f Boulder, CO g (303) 444-7270 g Portland, OR .8 (503) 636-4338 1 Wastilngton, D.C. ^ (301)577-7830

Remarks

Condition of Samples 1 Ipnn Renpjpt-

Custody Seal Intact: i—> i—> i—> ^ • Yes • No Q None

Relinquished by:

Relinquished by: (Signature)

Date/Time:

Date/Time:

Received by:

Received by: (Signature)

Date/Time:

Date/Time: (Signature) (Signature)

Distribution: White and Yellow Copies - Accompany Shipment; Pink Copy - Project File 2061 AR301623AR301623

3

Stendardl Test Method for Determination of

Content of Soi

AR301624AR301624

I

<1 Designation: D 2216 - 92

Standard Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock^

( •

This standard is issued under the fixed designation D 2216; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (c) indicates an editorial change since the last revision or reapproval.

1. Scope 1.1 This test method covers the laboratory determination

of the water (moisture) content of soil, rock, and similar materials by mass. For simplicity, the word "material" hereinafter also refers to either soil or rock, whichever is most applicable.

1.2 The water content of a material is defined by this standard as the ratio, expressed as a percentage, of the mass of "pore" or "free" water in a given mass of material to the mass of the solid material.

1.3 The term "solid particles" as used in geotechnical engineering is typically assumed to mean naturally occurring mineral particles of soil and rock that are not readily soluble in water. Therefore, the water content of materials con­taining extraneous matter (such as cement, and the like) may require special treatment or a qualified definition of water content. In addition, some organic materials may be decom­posed by oven drying at the standard drying temperature for this method (110°C). Materials containing gypsum (calcium sulfate dihydrate or other compounds having significant amounts of hydrated water) may present a special problem as this material slowly dehydrates at the standard drying temperature (110°C) and at very low relative humidities, forming a compound (calcium sulfate hemihydrate) which is not normally present in natural materials except in some desert soils. In order to reduce the degree of dehydration of gypsum in those materials containing gypsum, or to reduce decomposition in highly organic soils, it may be desirable to dry these materials at 60°C or in a desiccator at room temperature. Thus, when a drying temperature is used which is different from the standard drying temperature as defined by this te$t method, the resulting water content may be different from standard water content determined at the standard drying temperature.

NOTE 1—Test Metfiods D 2974 provides an alternate procedure for determining water content of peat materials.

1.4 Materials containing water with substantial amounts of soluble solids (such as salt in the case of marine sediments) when tested by this method will give a mass of solids which includes the previously soluble solids. These materials re­quire special treatment to remove or account for the presence of precipitated solids in the dry mass of the

' This method is under the Jurisdiction of ASTM Committee D-18 on Soil and Rock and is the direct responsibility of Subcommittee D 18.03 on Texture, Plasticity and Density Characteristics of Soils.

Current edition approved June 15, 1992. Published August 1992. Originally published asD2216-63T. Last previous edition D 2216 - 90".

specimen, of a qiialified definition of water content must be used.

1.5 This test method requires several hours for proper drying of the water content specimen. Test Method D 4643 provides for drying of the test specimen in a microwave oven which is a shorter process.

1.6 This standard requires the drying of material in an oven at high temperatures. If the material being dried is contaminated with certain chemicals, health and safety hazards can exist. Therefore, this standard should not be used in determining the water content of contaminated soils unless adequate health and safety precautions are taken.

1.7 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appro­priate safety and health practices and determine the applica­bility of regulatory limitations prior to use.

2. Referenced Documents

2.1 ASTM Standards: D653 Terminology Relating to Soil, Rock, and Contained

Fluids^ D2974 Test Methods for Moisture, Ash, and Organic

Matter of Peat and Other Organic Soils^ D4220 Practice for Preserving and Transporting Soil

Samples^ D 4318 Test Method for Liquid Limit, Plastic Limit, and

Plasticity Index of Soils^ D4643 Test Method for Determination of Water

(Moisture) Content of Soil by the Microwave Oven Method^

D4753 Specification for Evaluating, Selecting, and Speci­fying Balances and Scales for Use in Soil and Rock Testing^

E 145 Specification for Gravity-Convection And Forced-Ventilation Ovens-*

3. Terminology 3.1 Refer to Terminology D 653 for standard definitions

of terms. 3.2 Description of Term Specific to This Standard: 3.2.1 water content (of a material)—the ratio of the mass

of water contained in the pore spaces of soil or rock rnaterial, to the solid mass of particles in that material, expressed as a percentage.

^ Annual Book of ASTM Standards, Vol 04.08. 3 Annual Book of ASTM Standards, Vol 14.02.

188

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IK '

4.,Summary of Test Method

: 4.1 A test specimen is dried in an oven to a constant mass. The loss of mass due to drying is considered to be water. The water content is calculated using the mass of water and the niass of the dry specimen.

5. Significance and Use

,:5.1 For many materials, the water content is one of the most significant index properties used in establishing a correlation between soil behavior and its properties.

5.2 The water content of a material is used in expressing the iphase relationships of air, water, and solids in a given volume of material.

5.3 In fine-grained (cohesive) soils, the consistency of a given soil type depends on its water content. The water content of a soil, along with its liquid and plastic limits as determined by Test Method D 4318, is used to express its relative consistency or liquidity index.

6. Apparatus 6.1 Drying Oven, thermostatically-controlled, preferably

of the forced-draft type, meeting the requirements of Speci­fication E 145 and capable of maintaining a uniform temper­ature of 110 ± 5°C throughout the drying chamber. i 6.2 Balances—All balances must meet the requirements

of: Specification D 4753 and this Section. A Class GPl balance of 0.01 g readability is required for specimens having a mass of up to 200 g (excluding mass of specimen con­tainer) and a Class GP2 balance of O.lg readability is required for specimens having a mass over 200 g. • 6:3 Specimen Containers—Suitable containers made of

material resistant to corrosion and change in mass upon repeated heating, cooling, exposure to materials of varying pH, and cleaning. Containers with close-fitting lids shall be used for testing specimens having a mass of less than about 200 g; while for specimens having a mass greater than about 200 g, containers without lids may be used. One container is needed for each water content determination.

NOTE 2—The purpose of close-fitting lids is to prevent loss of moisture from specamens before initial mass determination and to prevent absorption of moisture from the atmosphere foUoviing drying and before final mass determination.

6.4 Desiccator—A desiccator cabinet or large desiccator jar of suitable size containing silica gel or anhydrous calcium phosphate. It is preferable to use a desiccant which changes color to ii\dicate it needs reconstitution. See Section 10.5.

; NOTE 3-Drierite.

-Anhydrous calcnum sulfate is sold under the trade name

. 6i5 Container Handling Apparatus, gloves, tongs, or suit­able holder for moving and handling hot containers after drying.

6.6 Miscellaneous, knives, spatulas, scoops, quartering cloth, sample splitters, etc, as required. ..'SirKr:..

7i Samples •i;7.1 Samples shall be preserved and transported in accor­

dance with Practice 4220 Groups B, C, or D soils. Keep the samples that are stored prior to testing in noncorrodible airtight containers at a temperature between approximately 3 and 30°C and in an area that prevents direct contact with

sunlight. Disturbed samples in jars or other containers shall be stored in such a way as to prevent or minimize moisture condensation on the insides of the containers.

7.2 The water content determination should be done as soon as practicable after sampling, especially if potentially corrodible containers (such as thin-walled steel tubes, paint cans, etc.) or plastic sample bags are used.

8. Test Specimen 8.1 For water contents being determined in conjunction

with another ASTM method, the specimen mass require­ment stated in that method shall ht used if one is provided. If no minimum specimen mass is provided in that method then the values given before shall apply.

8.2 The minimum mass of moist material selected to be representative of the total sample, if the total sample is not tested by this method, shall be in accordance with the following:

aximum particle size (100%

passing)

2 mm or less 4.75 mm

9.5 mm 19.0 mm 37.5 mm 75.0 mm

Standard Sieve Size

No. 10 No. 4 Vs-in. y4-in. 1 Vi in. 3-in.

Recommended minimum mass of

moist test spec­imen for water

content reported to ±0.1 %

20 g 100 g 500 g 2.5 kg 10 kg 50 kg

Recommended minimum rriass of

moist test spec­imen for water

content reported t o ± l %

20 g* 20 g* 50 g

.250g I k g 5 kg

NOTE—*To be representative not less than 20 g shall h>e used.

8.2.1 If the total sample is used it does not have to meet the minimum mass requirements provided in the table above. The report shall indicate that the entire sample was used.

8.3 Using a test specimen smaller than the minimum indicated in 8.2 requires discretion, though it may be adequate for the purposes of the test. Any specimen used not meeting these requirements shall be noted in the report of results.

8.4 When working with a small (less than 200g) specimen containing a relatively large gravel particle, it is appropriate not to include this particle in the test specimen. However, any discarded material shall be described and noted in the repiort of the results.

' 8.5 For those samples consisdng entirely of intact rock, the minimum specimen mass shall be 500 g. Representative portions of the sample may be broken into smaller particles, depending on the sample's size, the container and balance being used and to facilitate drying to constant mass, see Section 10.4.

9. Test Specimen Selection 9.1 When the test specimen is a portion of a larger

amount of material, the specimen must be selected to be representative of the water condition of the entire amount of material. The manner in which the test specimen is selected depends on the purpose and application of the test, type of material being tested, the water condition, and the type of sample (from another test, bag, block, and the likes.)

9.2 For disturbed samples such as trimmings, bag sam­ples, and the like, obtain the test specimen by one of the

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following methods (listed in order of preference): 9.2.1 If the material is such that it can be manipulated

and handled without significant moisture loss, the material should l)e mixed and then reduced to the required size by quartering or splitting;

9.2.2 If the material is such that it cannot be thoroughly mixed and/or split, form a stockpile of the material, mixing as much as possible. Take at least five portions of material at random locations using a sampling tube, shovel, scoop, trowel, or similar device appropriate to the maximum particle size present in the material. Combine all the portions for the test specimen.

9.2.3 If the material or conditions are such that a stockpile cannot be formed, take as many portions of the material as possible at random locations that will best represent the moisture condition. Combine all the portions for the test specimen.

9.3 Intact samples such as block, tube, split barrel, and the like, obtain the test specimen by one of the following methods depending on the purpose and potential use of the sample.

9.3.1 Carefully trim at least 3 mm of material from the outer surface of the sample to see if material is layered and to remove material that is drier or wetter than the main portion of the sample. Then carefully trim at least 5 mm, or a thickness equal to the maximum particle size present, from the entire exposed surface or from the interval being tested.

9.3.2 Slice the sample in half. If material is layered see Section 9.3.3. Then carefully trim at least 5 mm, or a thickness equal to the maximum particle size present, from the exposed surface of one half, or from the interval being tested. Avoid any material on the edges that may be wetter or drier than the main portion of the sample.

NOTE 4—Migration of moisture in some cohesionless soils may require that the full section bie sampled!

9.3.3 If a layered material (or more than one material type is encountered), select an average specimen, or individual specimens, or both. Specimens must be properly identified as to location, or what they represent, and appropriate remarks entered on data sheets.

10. Procedure 10.1 Determine and record the mass of the clean and dry

specimen container (and its Ud, if used). 10.2 Select representative test specimens in accordance

with Section 9. 10.3 Place the moist test specimen in the container and, if

used, set the lid securely in position. Determine the m^ss of the container and moist material using a balance (See 6.2) selected on the basis of the specimen mass. Record this value.

NOTE 5—To prevent mixing of specimens and yielding of incorrect results, all containers, and Uds if used, should be numbered and the container numbers shall be recorded on the laboratory data sheets. The lid numbers should match the container numbers to eliminate confu­sion.

NOTE 6—To assist in the oven-drying of large test specimens, they should be placed in containers having a large surface area (such as pans) and the material broken up into smaller aggregations.

10.4 Remove the fid (if used) and place the container with moist material in the drying oven. Dry the material to a

constant mass. Maintain the drying oven at 110 ±5°C unless otherwise specified (see 1.3). The time required to obtain constant mass will vary depending on the type of material, size of specimen, oven type and capacity, and other factors. The influeiice of these factors generally can be established by good judgment, and experience with the materials being tested and the apparatus being used.

NOTE 7—In most cases, drying a test specrimen overnight (about 12 to 16 h) is sufficient. In cases where there is doubt concerning the' adequacy of drying, drying should bie continued until the change in mass after two successive periods (greater than 1 h) of drying is an insignifi­cant amount (less than about 0.1 %). Specimens of sand may often be dried to constant mass in a period of about 4 h, when a forced-draft oven is used.

NOTE 8—Since some dry materials may absorb moisture from moist specimens, dried specirnens should be removed before placing moist specimens in the same oven. However, this would not be applicable if the previously dried specimens will remain in the drying oven for an additional time period of about 16 h.

10.5 After the material has dried to constant mass remove the container from the oven (and replace the lid if used). Allow the material and container to cool to room tempera­ture or until the container can be handled comfortably with bare hands and the operation of the balance will not be affected by convection currents and/or its being heated. Determine the mass of the container and oven-dried material using the same balance as used in 10.3. Record this value. Tight fitting lids shall be used if it appears that the specimen is absorbing moisture from the air prior to determination of its dry mass.

NOTE 9—Cooling in a desiccator is acceptable in place of tight fitting lids since it greatly reduces absorption of moisture from the atmosphere during cooling especially for containers without tight fitting lids.

11. Calculation

11.1 Calculate the water content of the material as fol­lows:

w^[(M^,-MJI(M,, M<.)]x 100 = —!^x 100

where: w — water content, %, M^^^ = mass of container and wet specimen, g, Mcs = mass of container and oven dry specimen, g, M^ = mass of container, g, M^ = mass of water {M^ = M^m ~ ^cds)^ g, and Ms = mass of solid particles (M^ = ^cds ~ ^ X 8-

12. Report

12.1 The report (data sheet) shall include the following: 12.1.1 Identification of the sample (material) being tested,

such as boring number, sample number, test nurriber, container number etc.

12.1.2 Water content of the specimen to the nearest 1 % or 0.1 %, as appropriate based on the minimum sample used. If this method is used in concert with another method, the water content of the specimen should be reported to the value required by the test method for which the water content is beiiig determined.

12.1.3 Indicate if test specimen had a mass less than the minimum indicated in 8.2.

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12.1.4 Indicate if test specimen contained more than one material type (layered, etc.).

12.1.5 Indicate the method of drying if different from oven-drying at 110 ± 5°C.

12.1.6 Indicate if any matbrial (size: and amoiint) was excluded from the test specimen.

13. Precision and Bias 13.1 Statement on Bias—There is no accepted reference

value for this test method; therefore, bias cannot be deter­mined.

l?).2 Statements on Precision: 13.2.1 Single-Operator Precision—The single-operator

coefficient of variation has been found to be 2.7 percent.

Therefore, results of two properly conducted tests by the same operator with the same equipment should not be considered suspect unless they differvby,more than 7.8 percent of their mean! • 13.2.2 "Multilaboratory Precision-^The : multilaboratory coefficient of variation has been found to be 5.0 percent. Therefore, results of two properly conducted tests by dif­ferent operators using different equipment should not be considered suspect unless they differ by more than 14.0 percent of their mean.

14. Keywords 14.1 consistency; index property; laboratory; moisture

analysis; moisture content; soil aggregate; water content

The American Society for Testing and Materials fates no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users 61 this staridard are expressly advised that determination of the validity of any such patent riglits; and the risk of infringement of such rights, are entirely their own responsibility.

This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed fo ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASr/lf Committee on Standards, 1916 Race St., Philadelphia, PA 19103.

191

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m^ AR301628AR301628

Attaclimeinit 4

Standard Methods for the Examination of Water and Wastewater

AR301629AR301629

2-23

Source: Standard Methods for the Examination of Water and Wastewater Eighteenth Edition Copyright 1992 by American Public Health Association American Water Works Association Water Environment Federation

2310 ACIDITY*

2310 A. Introduction

Acidity of a water is its quantitative capacity to react with a strong base to a designated pH. The measured value may vary significantly with the end-point pH used in the determination. Acidity is a ineasure of an aggregate property of water and can be interpreted in terms of specific substances only when the

'Approved by Standard Methods Committee. 1990:

chemical compKJsition of the sample is known. Strong mineral acids, weak acids such as carbonic and acetic, and hydrolyzing salts such as iron or aluminum sulfates may contribute to the measured acidity according to the method of determination.

Acids contribute to corrosiveness and influence chemical re­action rates, chemical speciation, and biological processes. The measurement also reflects a change in the quality of the source water.

2310 B. Titration Method

1. General Discussion

a. Principle: Hydrogen ions present in a sample as a result of dissociation or hydrolysis of solutes react with additions of stand­ard alkali. Acidity thus depends on the end-point pH or indicator used. The construction of a titration curve by recording sample pH after successive small measured additions of titrant permits identification of inflection points and buffering capacity, if any, and allows the acidity to be determined with respect to any pH of interest.

In the titration of a single acidic species, as in the standard­ization of reagents, the most accurate end point is obtained from the inflection point of a titration curve. The inflection point is the pH at which curvature changes from convex to concave or vice versa.

Because accurate identification of inflection points may be difficult or impossible in buffered or complex mixtures, the ti­tration in such cases is carried to an arbitrary end-point pH based on practical considerations. For routine control titrations or rapid preliminary estimates of acidity, the color change of an indicator may be used for the end point. Samples of industrial wastes, acid mine drainage, or other solutions that contain appreciable amounts of hydrolyzable metal ions such as iron, aluminum, or manganese are treated with hydrogen peroxide to ensure oxidation of any reduced forms of polyvalent cations, and boiled to hasten hy­drolysis. Acidity results may be highly variable if this procedure is not followed exactly.

b. End points: Ideally the end point of the acidity titration should correspond to the stoichiometric equivalence point for neutralization of acids present. The pH at the equivalence point will dejjend on the sample, the choice among multiple inflection points, and the intended use of the data.

Dissolved carbon dioxide (CO,) usually is the major acidic component of unpolluted surface waters; handle samples from such sources carefully to minimize the loss of dissolved gases. In a sample containing only carbon dioxide-bicarbonates-carl>on-ates, titration to pH 8.3 at ZS^C corresponds to stoichiometric neutralization of carbonic acid to bicarbonate. Because the color change of phenolphthalein indicator is close to pH8.3 , this value generally is accepted as a standard end point for titration of total acidity, including CO, and most weak acids. Metacresol purple also has an end point at pH 8.3 and gives a sharper color change.

For more complex mixtures or buffered solutions selection of an inflection point may be subjective. Consequently, use fixed end points of pH 3.7 and pH 8.3 for standard acidity determi­nations via a potentiometnc titration in wastewaters and natural waters where the simple carbonate equilibria discussed above cannot be assumed. Bromphenol blue has a sharp color change at its end point of 3.7. The resulting titrations are identified, traditionally, as "methyl orange acidity" (pH 3.7) and "phen­olphthalein" or total acidity (pH 8.3) regardless of the actual method of measurement.

c. Interferences: Dissolved gases contributing to acidity or al­kalinity, such as CO, , hydrogen sulfide, or ammonia, may be lost or gained during sampling, storage, or titration. Minimize such effects by titrating to the end point promptly after opening sample container, avoiding vigorous shaking or mixing, protect­ing sample from the atmosphere during titration, and letting sample become no warmer than it was at collection.

In the potentiometnc titration, oily matter, suspended solids, precipitates, or other waste matter may coat the glass electrode and cause a sluggish response. Difficulty from this source is likely to be revealed in an erratic titration curve. Do not remove in­terferences from sample t>ecause they may contribute to its acid-

AR301630AR301630

.2-24 PHYSICAL & AGGREGATE PROPERTIES (2000)

ity. Briefly pause between titrant additions to let electrode come to equilibrium or clean the electrodes occasionally.

In samples containing oxidizable or hydrolyzable ions such as ferrous or ferric iron, aluminum, and manganese, the reaction rates at room temperature may be slow enough to cause drifting end points.

Do not use indicator titrations with colored or turbid samples that may obscure the color change at the end point. Residual free available,chlorine in the sample may bleach the indicator. Eliminate this source of interference by adding 1 drop of O.IM sodium thiosulfate (Na^SjO,).

ci. Selection of procedure: Determine sample acidity from the volume of standard alkali required to titrate a portion to a pH of 8.3 (phenolphthalein acidity) or pH 3.7 (methyl orange acidity of wastewaters and grossly polluted waters). Titrate at room temperature using a properly calibrated pH meter, electrically operated titrator, or color indicators.

Use the hot peroxide procedure (fl 4a) to pretreat samples known or suspected to contain hydrolyzable metal ions or re­duced forms of polyvalent cation, such as iron pickle liquors, acid mine drainage, and other industrial wastes.

Color indicators may be used for routine and control titrations in the absence of interfering color and turbidity and for prelim­inary titrations to select sample size and strength of titrant (H 4b).

e. Sample .size: The range of acidities found in wastewaters is so large that a single sample size and normality of base used as titrant cannot be specified. Use a sufficiently large volume of titrant (20 mL or more from a 50-mL buret) to obtain relatively good volumetric precision while keeping sample volume suffi-

jfij ciently small to permit sharp end points. For samples having acidities less than about 1000 mg as calcium carbonate (CaCO^)/ L, select a volume with less than 50 mg CaCO, equivalent acidity and titrate with 0.Q2N sodium, hydroxide (NaOH). For acidities greater than about 1000 mg as CaCO,/L, use a portion containing acidity equivalent to less than 250 mg CaCOj and titrate with O.IA^ NaOH. If necessary, make a preliminary titration to de­termine optimum sample size and/or normality of titrant.

/. Sampling and storage: Collect samples in polyethylene or borosilicate glass bottles and store at a low temperature. Fill bottles completely and cap tightly. Because waste samples may be subject to microbial action and to loss or gain of CO, or other gases when exposed to air, analyze samples without delay, pref­erably within 1 d. If biological activity is suspected analyze within 6 h. Avoid sample agitation and prolonged exposure to air.

2. Apparatus

a. Eleclrometric tilrator: Use any commercial pH meter or electrically operated titrator that uses a glass electrode and can be read to 0.05 pH unit. Standardize and calibrate according to the manufacturer's instructions. Pay special attention to tem­perature compensation and electrode care. If automatic tem­perature compensation is not provided, titrate at 25 ± 5°C.

b. Titration vessel: The size and form will depend on the elec­trodes and the sample size. Keep the free space above the sample as small as practicable, but allow room for titrant and full im­mersion of the indicating portions of electrodes. For conven­tional-sized electrodes, use a 200-mL, tall-form Berzelius beaker without a spout. Fit beaker with a stopper having three holes, to accommodate the two electrodes and the buret. With a min­

iature combination glass-reference electrode use a 125-mL or 250-mL erienmeyer flask with a two-hole stopper.

c. Magnetic stirrer. d. Pipets, volumetric. e. Flasks, volumetric, 1000-, 200-, 100-mL. /. Sure/i, borosilicate glass, 50-, 25-, 10-mL. g. Polyolefin bottle. 1-L.

3. Reagents

a. Carbon dioxide-free water: Prepare all stock and standard solutions and dilution water for the standardization procedure with distilled or deionized water that has been freshly boiled for 15 min and cooled to room temperature. The final pH of the water should be a 6.0 and its conductivity should be <2 p.mhos/ cm.

b. Potassium hydrogen phthalate solution, approximately 0.05M-Crush 15 to 20 g primary standard K H C R H J O ^ to about 100 rriesh and dry at 120°C for 2 h. Cool in a desiccator. Weigh 10.0 ± 0.5 g (to the nearest mg), transfer to a 1-L volumetric flask, and dilute to 1000 mL.

c. Standard sodium hydroxide titrant, Q.\N: Prepare solution approximately Q.\N as indicated under Preparation of Desk Re­agents (see inside front cover). Standardize by titrating 40.00 mL K H C R H J O J solution (36), using a 25-mL buret. Titrate to the inflection point (H la), which should be close to pH 8.7. Calculate normality of NaOH:

Norinality. / t X g

204.2 X C

where: A = g KHQHjOj weighed into 1-L nask, B = mL KHCtiHjOj solution taken for titration, and C = mL NaOH solution used.

Use the measured normality in further calculations or adjust to 0.1000/V; 1 mL = 5.00 mg CaCOj.

d. Standard sodium hydroxide titrant, 0.02N: Dilute 200 mL 0.1 A' NaOH to 1000 mL and store in a polyolefin bottle protected from atmospheric CO, by a soda lime tube or tight cap. Stand­ardize against KHC8H4O4 as directed in H 3c, using 15.00 mL KHCfiHjOj solution and a 50-mL buret. Calculate normality as above (H 3c); 1 mL = l.OOmgCaCOj.

e. Hydrogen peroxide, HjO,, 30%. / . Bromphenol blue indicator solution, pH 3.7 indicator: Dis­

solve 100 mg bromphenol blue, sodium salt, in 100 mL water. g: Metacresol purple indicator solution, pH 8.3 indicator: Dis­

solve loo mg metacresol purple in 100 riiL water. h. Phenolphthalein indicator solution, alcoholic, pH 8.3 indi­

cator. /. Sodium thiosulfate, O.iM: Dissolve 25 g Na,S20.,-5H20 aind

dilute to 1000 mL with distilled water.

4. Procedure

If sample is free from hydrolyzable metal ions and reduced forms of polyvalent cations, proceed with analysis according to b, c, OT d. If sample is known or suspected to contain such substances: pretreat according to a.

a. Hot peroxide treatment: Pipet a suitable sample (see H le) into titration flasks. Measure pH. If pH is above 4.0 add 5-mL

AR301631AR301631

ALKALINITY (2320)/lntroduction 2-25

incrernents of 0.02N sulfuric acid (H^SOj) (Section 2320B.3c) to reduce pH to 4 or less. Remove electrodes. Add 5 drops 30% H^O, and boil for 2 to 5 min. Cool to room temperature and titrate with standard alkali to pH 8.3 according to the procedure of Ad.

b. Color change: Select sample size and normality of titrant according to criteria of H le. Adjust sample to room temperature, if necessary, and with a pipet discharge sample into an erien­meyer flask, while keeping pipet tip near flask bottom. If free residual chlorine is present add 0.05 mL (1 drop) Q.\M Na,S203 solution, or destroy with ultraviolet radiation. Add 0.2 mL (5 drops) indicator solution and titrate over a white surface to a persistent color change characteristic of the equivalence point.*' Commercial indicator solutions or solids designated for the ap­propriate pH range (3.7 or 8.3) may be used. Check color at end point by adding the same concentration of indicator used with sample to a buffer solution at the designated pH.

c. Potentiomelric titration curve: 1) Rinse electrodes and titration vessel with distilled water and

drain. Select sample size and normality of titrant according to the criteria of H le. Adjust sample to room temperature, if nec­essary, and with a pipet discharge sample while keeping pipet tip near the titration vessel bottom.

2) Measure sample pH. Add standard alkali in increments of 0.5 mL or less, such that a change of less than 0.2 pH units occurs per increment. After each addition, mix thoroughly but gently with a magnetic stirrer. Avoid splashing. Record pH when a constant reading is obtained. Continue adding titrant and meas­ure pH until pH 9 is reached. Construct the titration curve by plotting observed pH values versus cumulative milliliters titrant added. A smooth curve showing one or more inflections should be obtained. A ragged or erratic curve may indicate that equi­librium was not reached between successive alkali additions. De­termine acidity relative to a particular pH from the curve.

d. Potentiomelric titration to pH 3.7 or 8.3: Prepare sample and titration assembly as specified in H 4cl). Titrate to prese­lected end-point pH (H Id) without recording intermediate pH values. As the end point is approached make smaller additions of alkali and be sure that pH equilibrium is reached before mak­ing the next addition.

5. Calculation

Acidity, as mg CaCOj/L [(A X B) - (C X D)] X 50 OOP

mL sample

where: A = mL NaOH titrant used, S = normality of NaOH, C = mL H^SOj used (11 4o), and D = normality of H2SO4.

Report pH of the end point used, as follows: "The acidity to pH = _ .mgCaCOj/L." If a negative value is obtained, determine the alkalinity according to Section 2320.

6. Precision and Bias

No general statement can be made about precision because of the great variation in sample characteristics. The precision of the titration is likely to be much greater than the uncertainties in­volved in sampling and sample handling before analysis.

Forty analysts in 17 laboratories analyzed synthetic water sam­ples containing increments of bicarbonate equivalent to 20 mg CaCOj/L. Titration according to the procedure of H 4d gave a standard deviation of 1.8 mg CaCOj/L, with negligible bias. Five

• laboratories analyzed two samples containing sulfuric, acetic, and formic acids and aluminum chloride by the procedures of Us 4b and 4d. The mean acidity of one sample (to pH 3.7) was 487 mg CaCOj/L, with a standard deviation of 11 mg/L. The bromphenol blue titration of the same sample was 90 mg/L greater, with a standard deviation of 110 mg/L. The other sample had a poten-tiometric titration of 547 mg/L, with a standard deviation of 54 mg/L, while the corresponding indicator result was 85 mg/L greater, with a standard deviation of 56 mg/L. The major dif­ference between the samples was the substitution of ferric am­monium citrate, in the second sample, for part of the aluminum chloride.

7. Bibliography

WINTER, J.A. & M.R. MIDGETT. 1969. FWPCA Method Study 1. Min­eral and Physical Analyses. Federal Water Pollution Control Ad­min., Washington, D.C.

BROWN, E. , M.W. SKOUGSTAD & M.J. FISHMAN. 1970. Methods for collection and analysis of water saniples for dissolved minerals and gases. Chapter Al m Book 5, Techniques of Water-Resources In­vestigations of United States Geological Survey. U.S. Geological Survey, Washington, D.C.

SNOEYENK, V.L . & D. JENKINS. 1980. Water Chemistry. John Wiley & Sons, New York, N.Y.

2320 ALKALINITY*

2320 A. Introduction

1. Discussion

Alkalinity of a water is its acid-neutralizing capacity. It is the sum of all the titratable bases. The measured value may vary

* ApiJroved by Standard Methods Committee. 1991.

significantly with the end-point pH used.. Alkalinity is a measure of an aggregate property of water and can be interpreted in terms of specific substances only when the chemical composition of the sample is known.

Alkalinity is significant in many uses and treatments of natural waters and wastewaters. Because the alkalinity of many surface

AR301632AR301632

2-26 PHYSICAL & AGGREGATE PROPERTIES (2000)

waters is primarily a function of carbonate, bicarbonate, and hydroxide content, it is taken as an indication of the concentra­tion of these constitutents. The measured values also may include contributions from borates, phosphates, silicates, or other bases if these are present. Alkalinity in excess of alkaline earth metal concentrations is significant in determining the suitability of a ' water for irrigation. Alkalinity measurements are used in the interpretation and control of water and wastewater treatment processes. Raw domestic wastewater has an alkalinity less than, or only slightly greater than, that of the water supply. Properly

operating anaerobic digesters typically have supernatant alka-linities in the range of 2000 to 4000 mg calcium carbonate (CaCO,)/L.'

2. Reference

1. POHLAND, F.G. & D.E. BLOODGOOD. 1963. Laboratory studies on mesophilic and thermophilic anaerobic sludge digestion. J. Water Poi-lut. Control Fed. 35:11.

2320 B. Titration Method

1. General Discussion

a. Principle: Hydroxyl ions present in a sample as a result of dissociation or hydrolysis of solutes react with additions of stand­ard acid. Alkalinity thus depends on the end-point pH used. For methods of determining inflection points from titration curves and the rationale for titrating to fixed pH end points, see Section 2310B.la.

For samples of low alkalinity (less than 20 mg CaCOj/L) use an extrapolation technique based on the near proportionality of concentration of hydrogen ions to excess of titrant beyond the equivalence point. The amount of standard acid required to re­duce pH exactly 0.30 pH unit is measiJred carefully. Because this change in pH corresponds to an exact doubling of the hydrogen ion concentration, a simple extrapolation can be made to the equivalence point.'•-

b. End points: When alkalinity is due entirely to carbonate or bicarbonate content, the pH at the equivalence point of the titration is determined by the concentration of carbon dioxide (CO,) at that stage. CO, concentration depends, in turn, on the total carbonate species originally present and any losses that may have occurred during titration. The pH values in Table 2320:1 are suggested as the equivalence points for the corresponding alkalinity concentrations as milligrams CaCO, per liter. "Phen­olphthalein alkalinity" is the term traditionally used for the quan­tity measured by titration to pH 8.3 irrespective of the colored indicator, if any, used in the determination. Phenolphthalein or

metacresol purple may be used for alkalinity titration to pH 8.3. Bromcresol green or a mixed bromcresol green-methyl red in­dicator may be used for pH 4.5.

c. Interferences: Soaps, oily matter, suspended solids, or pre­cipitates may coat the glass electrode and cause a sluggish re­sponse. Allow additional time between titrant additions to let electrode come to equilibrium or clean the electrodes occasion­ally. Do not filter, dilute, concentrate, or alter sample.

d. Selection of procedure: Determine sample alkalinity from volume of standard acid required to titrate a portion to a des­ignated pH taken from H \b. Titrate at room temperature with a properly calibrated pH meter or electrically operated titrator, or use color indicators. If using color indicators, prepare and titrate an indicator blank.

Report alkalinity less than 20 mg CaCOj/L only if it has been determined by the low-alkalinity method of II 4d.

Construct a titration curve for standardization of reagents. Color indicators may be used for routine and control titrations

in the absence of interfering color and turbidity and for prelim­inary titrations to select sample size and strength of titrant (see below).

e. Sample size: See Section 2310B.le for selection of size sam­ple to be titrated and normality of titrant, substituting 0.02N or 0.1/Vsulfuric (HjSOa) or hydrochloric (HCI) acid for the standard alkali of that method. For the low-alkalinity method, titrate a 200-mL sample with 0.02N H.SO^ from a 10-mL buret:

/ . Sampling and storage: See Section 2310B.1/.

TABLE 2320:1 END-POINT PH VALUES

Test Condit ion

Alkal in i ty , mg CaCO,/L:

30 150 500

Silicates, phosphates known or suspected

Roiitine or automated anal­yses

Industrial waste or system

complex

Total Alkal ini ty

4.9 4.6

4.3

4.5

4.5

4.5

End Point pH

Phenolphthalein Alkal ini ty

8.3' 8.3 8.3

8.3

8.3

8.3

2. Apparatus

See Section 2310B.2.

3. Reagents

a. Sodium carbonate solution, approximately G.05N: Dry 3 to 5 g primary standard Na,CO, at 250°C for 4 h and cool in a desiccator. Weigh 2.5 ± 0.2 g (to the nearest mg), transfer to a 1-L volumetric flask, fill flask to the mark with distilled water, and dissolve and mix reagent. Do not keep longer than I week.

b. Standard sulfuric acid or hydrochloric acid, 0.\N: Prepare acid solution of approximate normality as indicated under Prep­aration of Desk Reagents (see inside front cover). Standardize against 40.00 mL 0.05/V Na,CO, solution, with about 60 mL water, in a beaker by titrating potentiometrically to pH of aboiit 5. Lift out electrodes, rinse into the same beaker, and boil gently

AR301633AR301633

H ALKALINITY (2320)/Tlfration Method 2-27

for 3 to 5 min under a watch glass cover. Cool to room temper­ature, rinse cover glass into beaker, and finish titrating to the pH inflection point. Calculate normality:

where: A = mL standard acid used and N = normality of standard acid

Normality, N A X B

53.00 X C

where: A = g Na,CO, weighed into 1-L flask. B = mL Na,CO, solution taken for titration, and C = mL acid used.

Use measured normality in calculations or adjust to 0.1000/V; l*" mL 0.1000/V solution = 5.00 mg CaCO,.

c. Standard sulfuric acid or hydrochloric acid, 0.02/V.- Dilute 200.00 mL O.IOOOA' standard acid to 1000 mL with distilled or deionized water. Standardize by potentiometnc titration of 15.00 mL 0.05/V Na,CO, according to the procedure of % 3b; 1 mL = 1.00 mg CaCO,.

d. Bromcresol green indicator solution, pH 4.5 indicator: Dis­solve 100 mg bromcresol green, sodium salt, in 100 mL distilled water.

e. Mixed bromcresol green-methyl red indicator solution:^" Use either the aqueous or the alcoholic solution:

1) Dissolve 100 mg bromcresol green sodium salt and 20 mg methyl red sodium salt in 100 mL distilled water.

2) Dissolve 100 mg bromcresol green and 20 mg methyl red in 100 mL 95% ethyl alcohol or isopropyl alcohol.

/ . Metacresol purple indicator solution, pH 8.3 indicator: Dis­solve 100 mg metacresol purple in 100 mL water,

g. Phenolphthalein solution, alcoholic, pH 8.3 indicator. h. Sodium thiosulfate, O.IN: See Section 2310B.3;.

4. Procedure

a. Color change: See Section 2310B.4fo. b. Potentiomelric titration curve: Follow the procedure for de­

termining acidity (Section 2310B.4c), substituting the appropri­ate normality of standard acid solution for standard NaOH, and confinue titration to pH 4.5 or lower. Do not filter, dilute, con­centrate, or alter the sample.

C; Potentiomelric titration to preselected pH: Determine the appropriate end-point pH according to H lb. Prepare sample and titration assembly (Section 2310B.4c). Titrate to the end-point pH without recording intermediate pH values and without undue delay. As the end point is approached make smaller additions of acid and be sure that pH equilibrium is reached before adding more titrant.

d. Potentiomelric titration of low alkalinity: For alkalinities less than 20 mg/L titrate 100 to 200 mL according to the procedure of.1l 4c, above, using a 10-mL microburet and 0.02/V standard acid solution. Stop the titration at a pH in the range 4.3 to 4.7 and record volume and exact pH. Carefully add additional titrant to reduce the pH exactly 0.30 pH unit and again record volume.

5. Calculations

a. Potentiomelric titration to end-point pH:

A X N X 50 000

or

Alkalinity, mg CaCO.VL /t X f X 1000 mL sample

Alkalinity, mg CaCO,,/L tnL sample

where: 7 = titer of standard acid, mg CaCO^/mL.

Report pH of end point used as follows: "The alkalinity to pH = mg CaCO,/L"' and indicate clearly if this pH corresponds to an inflection point of the titration curve.

b. Potentiomelric titration of low alkalinity:

Total alkalinity, mg CaCO,/L

_ (2 g - C) X /V X 50 000 mL sample

where: B = mL titrant to first recorded pH, C = total mL titrant to reach pH 0.3 unit lower, and A' = normality of acid.

c. Calculation of alkalinity relationships: The results obtained from the phenolphthalein and total alkalinity determinations of­fer a means for stoichiometric classification of the three principal forms of alkalinity present in many waters. The classification ascribes the entire alkalinity to bicarbonate, carbonate, and hy­droxide, and assumes the absence of other (weak) inorganic or organic acids, such as silicic, phosphoric, and boric acids. It further presupposes the incompatibility of hydroxide and bicar­bonate alkalinities. Because the calculations are made on a stoi­chiometric basis, ion concentrations in the strictest serise are not represented in the results, which may differ significantly from actual concentrations especially at pH > 10. According to this scheme:

1) Carbonate (CO3-') alkalinity is present when phenol­phthalein alkalinity is not zero but is less than total alkalinity.

2) Hydroxide (OH") alkalinity is present if phenolphthalein alkalinity is more than half the total alkalinity.

3) Bicarbonate (HCO3 ) alkalinity is present if phenolphtha­lein alkalinity is less than half the total alkalinity. These rela­tionships may be calculated by the following scheme, where P is phenolphthalein alkalinity and T is total alkalinity (H \b):

Select the smaller value of P or [T—P). Then, carbonate al­kalinity equals twice the smaller value. When the smaller value is P, the balance {T-2P) is bicarbonate. When the smaller value is { T - P), the balance ( 2 P - 7) is hydroxide. All results are ex­pressed as CaCOj. The mathematical conversion of the results is shown in Table 2320:11. (A modification of Table 2320:11 that is more accurate when P — V,rhas been proposed.•*)

Alkalinity relationships also may be computed nomographi-cally (see Carbon Dioxide, Section 4500-CO,). Accurately meas­ure pH, calculate OH~ concentration as milligrams CaC03 per liter, and calculate concentrations of CO3'" and HCO3" as mil­ligrams CaC03 per liter from the OH~ concentration, and the phenolphthalein and total alkalinities by the following equations:

AR301634AR301634

'W""

2-28 PHYSICAL & AGGREGATE PROPERTIES (2000)

CO3'- = 2P - 2[OH-|

HCO.r = 7" - 2P-I- [OH-]

Similarly, if difficulty is experienced with the phenolphthalein end point, or if a check on the phenolphthalein titration is de­sired, calculate phenolphthalein alkalinity as CaCO, from the results of the nomographic determinations of carbonate and hy­droxide ion concentrations:

P = 1/2 fCO,--] + (OH-)

6. Precision and Bias

No general statement can be niade about precision because of the great variation in sample characteristics. The precision of the titration is likely to be much greater than the uncertainties in­volved in sampling and sample handling before the analysis.

In the range of 10 to 500 mg/L, when the alkalinity is due entirely to carbonates or bicarbonates, a standard deviation of 1 mg CaCO.JL can be achieved. Forty analysts in 17 laboratories analyzed synthetic samples containing increments of bicarbonate equivalent to 120 mg CaC03/L. The titration procedure of H 4b

TABLE 2320:11. ALKALINITY RELATIONSHIPS*

Bicarbonate Hydroxide Carbonate . Concen-

Result of. Alkalinity Alkalinity tration Titration as CaCOj as CaC03 as CaCOj

P = 0 P < V.,T P = 7,T P > '/,T P = f

0 0 0 .

2P - T T

0 2P 2P

2(T - P) 0

T T - 2P

0 0 0

'Key: P-phenolphthalein alkalinity; T-total alkalinity.

was used, with an end point pH of 4.5. The standard deviation was 5 mg/L and the average bias (lower than the true value) was 9 mg/L.-'

Sodium carbonate solutions equivalent to 80 and 65 mg CaCOj/. L were analyzed by 12 laboratories according to the procedure of H 4c.''The standard deviations were 8 and 5 mg/L, respectively, with negligible bias.' Four laboratories analyzed six samples hav­ing total alkalinities of about 1000 mg CaCOj/L and containing various ratios of carbonate/bicarbonate by the procedures of both H 4a and H 4c. The pooled standard deviation was 40 mg/L, with negligible difference between the procedures.

7. References

1. LARSON. T.E. & L.M. HENLEY. 1955. Determination of low alkalinity or acidity in water. Anal. Chem. 27:851.

2. THOMAS, J.F.J. & J.J. LYNCH. 1960. Determination of carbonate alkalinity in natural waters. /. Amer. Water Works Assoc. 52:259.

3. COOPER, S.S. 1941. The mixed indicator bromocresol green-methyl red for carbonates in water. Ind. Eng. Chem.. Anal. Ed. 13:466.

4. JENKINS, S.R. & R.C. MOORE. 1977. A proposed modification to the classical method of calculating alkalinity in natural waters. J. Amer. Water Works Assoc. 69:56.

5. WINTER. J .A . & M.R. MIDGETT. 1969. FWPCA Method Study ,1. Mineral and Physical Analyses. Federal Water Pollution Control Ad­min.. Washington. DC.

6. SMITH. R. 1980. Research Rep. No. 379, Council for Scientific and Industrial Research. South Africa.

8. Bibliography

AMERICAN SOCIETY FOR TESTING AND MATERIALS. 1982. Standard Methods for Acidity or Alkalinity of Water. Publ. D1067-70 (reap­proved 1977). American Soc. Testing & Materials, Philadelphia, Pa.

SKOUGSTAD M.W., M.J. FISHMAN, L.C. FRIEDMAN, D.E. ERDMAN. & S.S. DUNCAN. 1979. Methods for determination of inorganic sub­stances in water and fluvial sediments. In Techniques of Water-Resources Investigation of the United States Geological Survey. U.S. Geological Survey, Book 5, Chapter Al, Washington, D.C.

2330 CALCIUM CARBONATE SATURATION (PROPOSED)'

2330 A. Introduction

1. General Discussion

Calcium carbonate (GaCOj) saturation indices commonly are used to evaluate the scale-forming and scale-dissolving tenden­cies of water. Assessing these tendencies is useful in corrosion control programs and in preventing CaC03 scaling in piping and equipment such as industrial heat exchangers or domestic water heaters.

Waters oversaturated with respect to CaCOj tend to precipi­tate CaC03. Waters undersaturated with respect to CaCO^ tend

'Approved by Standard Methods Committee, 1989.

to dissolve CaC03. Saturated waters, i:e., waters in equilibriUrri with CaCOj, have neither CaCOj-precipitating nor CaC03-dissolving tendencies. Saturation represents the dividing line be­tween "precipitation likely" and "precipitation not likely." ',:

Several water quality characteristics must be measured to cal­culate the CaC03 saturation indices described here. Minimum requirements are total alkalinity (2320), total calcium (3500-Ca); pH (4500-H*), and temperature (2550). The ionic strength also must be calculated or estimated from conductivity (2510) or total dissolved solids (2540C) measurements. Measure pH at the sys­tem's water temperature using a temperature-compensated pH meter. If pH is measured at a different temperature, for example in the laboratory, correct the measured pH.''^ In measuring pH

AR301635AR301635

Attachment 5

Standard Test Methods for pH of Water

AR301636AR301636

d Designation: D 1293 - 95

Standard Test Methods for pHofWater^

This standard is issued under the fixed designation D 1293; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year oflast revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (>) indicates an editorial change since the last revision or reapproval.

This test method has been approved for use by agencies of the Department of Defense. Consult the DoD Index of Specifications and Standards for the specific year of issue which has been adopted by the Department of Defense.

1. Scope 1.1 These test methods cover the determination of pH by

electrometric measiu-ement using the glass electrode as the sensor. Two test methods are given as follows:

Sections

Test Method A—Precise Laboratory Measurement . . . . ! 8 to 15 Test Method B—Roiitine or Continuous Measurement 16 to 24

1.2 Test Method A covers the precise measurement of pH in water utilizing at least two of seven standard reference buffer solutions for instrument standardization.

1.3 Test Method B covers the routine measurement of pH in water and is especially useful for continuous monitoring. Two buffers are used to standardize the instrument under controlled parameters, but the conditions are somewhat less restrictive than those in Test Method A.

1.4 Neither test method is considered to be adequate for measurement of pH in water whose conductivity is less than about 5 nS/cm. Refer to Test Methods D 5128 and D 5464.

1.5 Precision and bias data were obtained using buffer solutions only. It is the user's responsibility to assure the validity of these test methods for untested types of water.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro­priate safety and health practices and determine the applica­bility of regulatory limitations prior to use.

2. Referenced Documents

2.1 ASTM Standards: D 1066 Practice for Sampling Steam^ D 1067 Test Methods for Acidity or Alkalinity of Water^ D 1129 Terminology Relating to Water^

- D 1192 Specification for Equipment for Sampling Water and Steam in Qosed Conduits^

D 1193 Specification for Reagent Water D 2777 Practice for Determination of Precision and Bias

of Applicable Methods of Committee D-19 on Water^ D 3370 Practices for Sampling Water from Closed

Conduits^ 'D5128 Test Method for On-Line pH Measurement of

Water of Low Conductivity^

" ' These test methods are under the jurisdiction of ASTM Committee D-I9 on Water and are the direct responsibility of Subcommittee Dt9.\ 1 on Standards for Water for Power Generation and Processes.

Current edition approved Oct. 10, 1995. Published Decemtjer 1995. Originally published as D 1293 - 53 T. Last previous edition D 1293 - 84 (1990):

'^AnnualBookof ASTM Standards, yo \ \ \ . 0 \ .

D5464 Test Methods for pH Measurement of Water of Low Conductivity^

E 70 Test Method for pH of Aqueous Solutions with the Glass Electrode^

3. Terminology

3.1 Definitions—For definitions of terms used in these test methods, refer to Terminology D 1129.

3.2 Description of Term Specific to This Standard: 3.2.1 pH—the pH of an aqueous solution is derived from

E, the electromotive force (emO of the cell

glass electrode I solution reference electrode

(where the double vertical line represents a Uquid junction) when the electrodes are immersed in the solution in the diagrammed position, and E^ is the electromotive force obtained when the electrodes are immersed in a reference buffer solution. For use in the operational definition, the sign of the measured potential difference indicated by many pH meters must be reversed because the electrode configuration used with these meters is the following:

reference electrode solution | glass electrode

With the assigned pH of the reference buffer designed as pH^, and E and E, expressed in volts is the following:"

pH = pH^ + (E - E J F 2.3026 RT

where: F = Faraday, R = gas constant, and T = absolute temperature,/(°C)-I-273.15. The reciprocal of F/2.3026 RT is known as the slope of the electrode, and is the expected difference in observed volt^e for two measurements one pH unit apart. Values of the slope at various temperatures are given in Table 1.

4. Summary of Test Method 4.1 The pH meter and associated electrodes are standard­

ized against two reference buffer solutions that closely bracket the anticipated sample pH. The sample measure­ment is made under strictly controlled conditions and prescribed techniques.

5. Signiflcance and Use 5.1 The pH of water is a critical parameter affecting the

^ Annual Book of ASTM Standards, WQ\\5.05. * Bates, R. G., Determination ofpH: Theory and Practice, 2nd Ed., J. Wiley and

Sons, New York, 1973, p. 29.

129

AR301637AR301637

D1293

TABLE 1 Slope Factor at Various Temperatures

Temperature, °C Slope, millivolts

li.;ir-:iHi:

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

54.20 55.19 56.18 57.17 58.17 59.16 60.15 61.14 62.13 63.13 64.12 65.11 66.10 67.09 68.09 69.08 70.07 71.06 72.05 73.05

solubility of trace minerals, the ability of the water to form scale or to cause metalUc corrosion, and the suitability of the water to sustain living organisins. It is a defined scale, based on a system of buffer solutions^ with assigned values. In pure water at 25°C, pH 7.0 is the neutral point, but this varies with temperature and the ionic strength of the sample.^ Pure water in equilibrium with air has a pH of about 5.5, and, most natural uncontaminated waters range between pH 6 and pH 9.

6. Purity of Reagents 6.1 Reagent grade chemicals shall be used in all tests,

except as specifically noted for preparation of reference buffer solutions. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chem­ical Society, where such specifications are available.^ Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.

6.2 Purity of Water—Unless otherwise indicated, refer­ences to water shall be understood to mean reagent water conforming to Specification D 1193, Type I.

7. Sampling 7.1 Collect samples in accordance with Practice D 1066,

Specification D1192, or Practices D 3370, whichever is applicable.

' "Standard Reference Materials: Standardization of pH Measurements" Wu. and Koch, i>4BS Special Publications No. 260-53, 1988.

' The relative acidity or alkalinity measured by pH should not be conAised with total alkalinity or total acidity (for example, Test Methods D 1067). Thus, 0.1 M HCI and 0.1 M acetic acid have the same total acidity, but the HCI solution will be more acidic (approximately pH 1 versus pH 3.).

''Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed l>y the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), RockviUe, MD.

TEST METHOD A—PREOSE LABORATORY MEASUREMENT O F p H

8. Scope , 8.1 This test method covers the precise measurement of

pH in water under strictly controlled laboratory conditions.

9. Interferences 9.1 The glass electrode reliably measures pH in nearly all

aqueous solutions and in general is not subject to solution interference from color, turbidity, colloidal matter, oxidants, or reductants.

9.2 The reference electrode may be subject to interfer­ences and should be chosen to conform to all requirements of Sections 10 and 12. Refer also to Appendix XI. 3.

9.3 The true pH of an aqueous solution or extract is affected by the temperature. The electromotive force be­tween the glass and the reference electrode is a function of temperature as well as pH. The temperature effect can be compensated for automatically in many instruments or can be manually compensated for in most other instruments. The temperature compensation corrects for the effect of changes in electrode slope with temperature but does not correct for temperature effects on the chemical system being monitored. It does not adjust the measured pH to a common temperature; therefore, the temperature should be reported for each pH measurement. Temperature effects are discussed further in Appendix XI.2.

9.4 The pH response of the glass electrode/reference electrode pair is imperfect at both ends of the pH scale. The indicated pH valiie of highly alkaline solutions may be too low. See Appendix XI.5.1. The indicated pH value of strong aqueous solutions of salts and strong acids having a pH less than 1, will often be higher than the true pH value. Interferences caii be minimized by the selection of the proper glass and reference electrodes for measurements in highly alkaUne or acidic solutions.

9.5 A few substances sometimes dispersed in water appear to poison the glass electrode. A discussion of this subject is given in Appendix XI.4.

10. Apparatus 10.1 Laboratory pH Meter—Almost all commercially

available meters are of the digital type and will have either manual or automatic calibration, and either manual or automatic temperature (slope) correction. All four types are permissible. However, readability to 0.01 pH is essential (Section 14), and the abihty to read in miUivolts is useftil in troubleshooting.

\0.2 Glass Electrode^-The pH response of the glass electrode shall conform to the requirements set forth in 12.1 through 12.5. The glass electrode lead wire shall be shielded. New glass electrodes and those that have been stored dry shall be conditioned and maintained as recommended by the manufacturer.

10.3 Reference Electrode—This may be used as separate "half ceU," or it may be purchased integral with the glass pH electrode body, as a combination electrode. The internal refereiice element may be calomel (mercury/mercurous chloride), silver/silver chloride, or an iodide-iodine redox couple. For best performance, the reference element should

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be the same type in both the rieference electrode and inside the pH electrode. For all three types,, the junction between the reference filUng solution and the sample may be either a flowing or nonflovring junction. The flowing liquid junction-type unit ensures that a fresh liquid junction is formed for each measurement and shall be used for Test Method A determinations. If a saturated calomel electrode is used, some potassium chloride crystals shall be contained in the saturated potassium chloride solution. If the reference elec­trode is of the flowing junction type, the design of the electrode shall permit a fresh liquid junction to be formed between the reference electrode solution and the buffer standard or tested water for each measurenient and shall allow traces of solution to be washed from the outer surfaces of the electrodes. To ensure the desired slow outward flow of reference electrode solution, the solution pressure inside the liquid junction should be kept somewhat in excess of that outside the junction. In honpressurized applications, this requirement can be met by maintaining the inside solution level higher than the outside water level. If the reference electrode is of the nonflowing junction type, these outward flow and pressurization considerations do not apply. The reference electrode and junction shall perform satisfactorily as required in the standardizing procedure described in 12.1 through 12.5. A discussion of reference electrodes is given in Appendix X1.3.

10.4 Temperature Compensator—The thermocompensa-tor is a temperature-sensitive resistance element immersed in the water sample with the electrodes. The thermocompensa-toi" automatically corrects for the change in slope of the glass electrode (with change of temperature) but does not correct for actual changes in sample pH with temperature. The automatic thermocompensator is not required if the water temperature is essentially constant and the analyst chooses to use the manual temperature compensation feature of the pH meter.

11. Reagents 11.1 Reference Buffer Solutions- -The pH values of the

reference buffer solutions measured at several temperatures are listed in Table 2. Table 3 identifies each buffer salt by its National Institute of Standards and Technology (NIST) number and provides a recommended drying procedure prior to use. The current renewal of each NIST standard reference material should be used. Keep the five reference buffer solutions with pH less than 9.5 in bottles of chemically resistant glass. Keep the calcium hydroxide solutions in a plastic bottle that is nonporous to air (that is, polypropylene or h i ^ density polyethylene). Keep aU the reference buffer solutions well-stoppered and replace at a shelf age of 3 months, or sooner if a visible change is observed.

11.1.1 Borax Reference Buffer Solution (pfL, ="9 18 at 25°C)^Dissolve 3-80 g of sodium tetraborate decahydrate (Na2B407- IOH2O) in vvater and dilute to 1 L. .

11.1.2 Calcium Hydroxide Reference Buffer Solution (pH^ = 12.45 at 25°C)—Prepare pure calcium hydroxide (Ca(OH)2) from well-washed calcium carbonate (CaCOj) of low-alkaH grade by slowly heating the carbonate in a platinum dish at 1000°C and calcining for at least 45 min at that temperature. After cooling, add the calcined product slowly to water with stirring, heat the resultant suspension to boiling, cool, and filter through a funnel having a fritted-glass disk of medium porosity. Collect the solid from the filter, dry it in an oven at 110°C, and crush it to a uniform and fine granular state. Prepare a saturated calcium hydroxide solu­tion by vigorously shaking a considerable excess (about 3 g/L) of the fine granular product in water at 25°C in a stoppered plastic bottle (that is, polypropylene or high density polyethylene) that is essentially nonporous to gases. Allow the gross excess of solid to settle and filter the solution with suction through a fritted-glass funnel of medium porosity. The filtrate is the reference buffer solution. Con­tamination of the solution with atmospheric carbon dioxide renders it turbid and indicates need for replacement.

11.1.3 Phosphate Reference Buffer Solution {pH^ = 6.86 at 25°C)^Dissolve 3.39 g of potassium dihydrogeri phosphate (KH2PO4) and 3.53 g of anhydrous disodium hydrogen

TABLE 2 p H , of Reference Buffer Solut ions^

• ' Temperature, °C

0 5

10 15

- i ^ l ; . - . 20 . - • .

. ^ - • •• - 2 5

•-. 3 0 •-

35 40 45

' • G '• • : . . • .

50 55 60 70

80 90

: 95

Tetroxalate Solution

1.67 1.67 1.67 1.67

: 1-68

1.68 1.68 1.69 1.69 1.70

1.71 1.72 • 1.72 1.74

. 1.77 1.79 1.81,,

Tartrate Solution

3.56 • - 3 . 5 5

3.55 3.55 3.55

3.55 3.55 3.56 3.58

3.61 3.65 3.67

Phthalate Solution

4.00 4.00 4.00 4.00 4.00

4.00 4.01 4.02-4.03 4.04

4.06 : 4.07 4.09 4.12

4.16 i 4.19 4.21

Phosphate Solution

6.98 6.95 6.92 6.90 6.88

6.86 6.85 6.84 6.84

' 6.83

6.83 , , 6:83 :

6.84 , 6.85

6.86. 6.88 6.i59

Borax Solution

9.46 9.39 9.33 9.28

• . • - . : • • 9 . 2 3

9.18 9.14 9.11

. 9.07 9.04

9.02 8.99 8.96 8.92

8.89 8.85 , 8.83

Sodium Bicartxinate Sodium Cartxinate

10.32 10.25 10.18 10.12 10.06

iO.01 9.97 9.93 9.89 9.86

9.83

Calcium Hydroxide Solutions

13.42 13.21 13.00 12.81 12.63

12.45 12.29 12.13 11.98 11.84

11.71 11.57 . 11.45

.: ' ' For a discussion of the inanner in which these pH values were assigned, see Bates, R. G.,,"Revised Standard Values for pH Measurements from 0 to 95''C," Journal offlesearc/), NBS, Vol 66A. 1962, p. 179.

« This tMJffer is liot prepared from NIST standard refei-ence materials. The uncertainty of the listed pH values may tie greater than for the ottier buffers given. •

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TABLE 3 National Institute of Standards and Technology (NIST) Materials for Reference Buffer Soliitions

s

NIST Standard Reference , Material D^ignation.

187 186

•' 186 185 188 189 191

. 192

Buffer Sa l f :

Borax (sodium tetraborate decahydrate) , , disodium hydrogen phosphate •.

potassium dihydrogen phosphate' potassium hydrogen phthalate

; potassium hydrogen tartrate potassium tetroxalate dihydrate sodium bicartxxiate

" sodiufn cartxinate

Drying Procedure

Drying not necessary (this.salt should not t>e oven-dned) 2 h in oven at 130° 2hinoveri'at 130°C 2hinovenat l iO 'd drying not necessary should, not be dried should not be dried 2 h in oven at 275°C • '

- -it

"'1 •* The Ijuffer salts listed can be purchased from the Standard Reference Materials Program, National Institute of Standards arid Technology, Gaittiiersburg, MD 20899 ^ i

phosphate (Na2HPd4) in water and dilute to 1 L. 11.1.4 Phthalate Reference Buffer Solution (pH^ = 4.00 at

25°C)-^Dissolve 10:12 g bf potassium hydrogen phthalate (KHC8H4O4) in water arid dilute to 1 L.

11.1.5 Tartrate Reference Buffer Solution (pH, = 3.56 at 25°C)—Shake vigorously an excess (about 75 g/L) of potas­sium hydrogen tartrate (KHC4H4O6) with 100 to 300 mL of water at 25°C in a glass-stoppered bottle. Filter, if necessary, to remove suspended salt. Add a crystal of thymol (about 0.1 g) as a preservative. ,

11.1.6 Tetroxalate Reference Buffer Solution (pH^ = 1:68 at 25°C)—Dissolve 12.61 g of potassium tetroxalate dihydrate (KHC2O4 • H2C2O4 • 2H2O) in water and dilute to 1 L . • •• • • . •

11.1.7 Sodium Bicarbonate^Sodium Carbonate Refer­ence Buffer Solution (pH, = 10.01 at 25°C)—Dissolve 2.092 g of sodium bicarbonate (NaHC03) and 2.640 g of sodium carbonate (Na2C03) in water and dilute to 1 L.

11.2 Other Buffer Solutions—A bufler solution other than that specified may be used as a working standard in the method providing that in each case such a solution is first checked against the corresponding reference buffer solution, using the procedures of the method, and is found to differ by not more than 0.02 pH unit.

11.3 Commercial Buffer Solutions—Commercially avail­able prepared bufler solutions are not acceptable for the standardization in Test Method A.

12. Standardization of Assembly 12.1 Tiim on the instrument, allow it to warm up

thoroughly, and bring it to electrical balance in accordance vrith the manufacturer's instructions. Wash the glass and reference electrodes and the sample container with three changes of water or by means of flowing stream from a wash bottle. Form a fresh liquid junction if a sleeve-type reference junction is used. Note the temperature of the water to be tested. If temperature compensation is to be manual, adjust the temperature dial of the meter to correspond to the temperature of the water to be tested and allow time for all buffers, solutions, and electrodes to equilibrate thermally.

12.2 Select at least two reference buffer solutions, the pHj values of which bracket the anticipated pH (refer to Table 2). Warm or cool the reference solutions as necessary to match within 2°C the temperature of the solution to be tested. Fill the sample container with the first reference buffer solution and immerse the electrodes. Stir the solution as described in 13-3.

12.3 Set the pHj value of the reference buffer solution at the temperature of the buffer, as read from Table 2 or

' . • • , ^ •• • ' f ' ^

interpolated from the data therein, according to the manu-?^ facturer's instructions. • ^

• - • • • • : • • 1 l y 5 ^ ' ^

12.4 Empty the sample container and repeat, iising suc-*' cessiye portions of the reference buftisr solution, until twoj, successive readings are obtained without adjustment of the ^ system. These readings should differ from the pHj value; of> the buffer solution by not more than 0.02 pH unit.

NOTE 1-^Iflhe temperature bfthe electrode differs appreciably from ' that of the solution to be tested, use several portions of solution and iminerse the electrodes deeply to assure that both the electrodes and the solution are at the desired temperature. To reduce the effects of thermal lag, keep the temperature of electrodes, reference buffer solutions, and the wash as close to that of the water sample as jxissible.

12.5 Wash the electrodes and the sample container three times with water. Place the second reference buffer solution in the sample container, and measure the pH. Adjust the slope control only until the reading (corresponds to the temperature corrected value of the second reference buffer solution. Use additional portions of the second reference ; buffer solution, as before, until two successive readings differ ' by not more than 0.02 pH imit. The assembly shaU be judged ,: to be operating satisfactorily if the pH reading obtained for the second reference buffer solution agrees with its assigned pHj value within 0.05 (or less) pH units.

12.6 If only an occasional pH determination is made, standardize the assembly each time it is used. In a long series of measurements, supplemental interim checks at regular intervals are recommended. Inasmuch as commercially available pH assemblies exhibit different degrees of measure­ment stabihty, conduct these checks at intervals of 30 min, unless it is ascertained that less frequent checking is satisfac­tory to ensure the performance described in 12.2 to 12.5.

13. Procedure 13.1 Standardize the assembly with two reference buffer

solutions as described in 12.2 to 12.5 and then wash the electrodes with three changes of water or by means of a flowing stream from a wash bottle.

13.2 Place the water sample in a clean glass beaker provided with a stirring bar and either a thermometer (for meters with manual temperature compensation) or an ATC probe (for meters yvith automatic temperature compensa­tion).

13.3 Stir during the period of pH measurement at a rate that will prevent splashing and that will avoid loss or gain of acidic or basic gases by interchange with the atmosphere. When necessary, stir briskly enough to intermix the phases of a nonhomogeneous water sample. Stop the stirrer during periods of measurement if fluctuations in readings are

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observed. (See Appendix XI.3.4 and XI.4.3). ; 13.4 Insert the electrodes and determine a preliminary pH

value (since this value may drift somewhat, it should be considered an estimated value). Measure successive portions of the water sample until readings on two successive portions differ by no more than 0.03 pH unit, and show'drifts of less than 0.02 pH unit in 1 min. Two or three portions will usually be sufficient if the water is well buffered.

13.5 Record the pH and temperature of the sample. 13.6 Measure the pH of slightly buffered waters (that are

in equilibrium with air) essentially as described in 13.1 to 13.5, but measure the pH of successive portions until the readings for two successive portions differ by no naore than 0.1 pH unit. Six or more portions may be necessary.

NOTE 2—Take special precautions if the sample is not in equilibrium with the carbon dioxide of the atmosphere protecting the sample from exposure to the air during measurement. Measurement of unbuffered or slightly buffered samples is more reliably made in flow-type cells as described in NOTE 4. Test Methods D 5464 describe additional precau­tions that should be taken if the electrical conductivity of the sample is less than about 5 nS/cm.

14. Report 14.1 Report the temperature of the measurement of the

nearest TC. 14.2 Report the pH of the test solution to the nearest 0.01

pH unit when the pH measurement lies between 1.0 and 12.0.

14.3 Report the pH of the test solution to the nearest 0.1 pH unit when the pH measurement is less than 1.0 or greater than 12.0.

15. Precision and Bias*

15.1 The information summarized in this section was derived from an interlaboratory study performed in 1973 on four buffer solutions having pH values of approximately 3.7, 6.5, 8.2, and 8.4. Eleven laboratories (fourteen operators, with one laboratory providing four operators) analyzed each solution in duplicate and replicated the analysis on another day for a total of 224 determinations. A variety of commer­cial meters was used in this study. It is assumed that all measurements were made at room temperature.

15.2 Statistical treatment of the data conforms to the recommendations of Practice D 2777. Further information, based on a different statistical interpretation, can be found in Test Method E 70.

15.3 Precision—Ihe overall and single-operator precision of this test method varies with pH as shown in Fig. 1.

15.4 Bias—The pH values of the buffer solutions, as determined using a gaseous hydrogen electrode, are com­pared with values obtained using this test method in Table 4.

15.5 Precision and bias data were obtained using buffer solutions only. It is the user's responsibility to assure the vahdity of the standards for untested types of water.

* Supporting data for these test methods have been filed at ASTM Headquar­ters. Request Research Report RR: D19-) H1.

TEST METHOD B—ROUTINE OR CONTINUOUS MEASURE-, •• - - MENTOFpH

16. Scope 16.1 This test method is used for the routine measure­

ment of pH in the laboratory and the measurement of pH under various process conditions.

17: Summary of Test Method

17 . rA direct standardization technique is employed in this test method for routine batch samples. Two buffers are used to standardize the instrument under controlled param­eters, but the conditions are somewhat less restrictive than those in Test Method A. An indirect standardization proce­dure is used on flowing systems in which grab samples are removed periodically in order to compare a monitored pH value (of the system) with the reading of a laboratory pH meter.

18. Interferences 18.i For information on interferences, see Section 9 and

Appendix X1.4.

19. Apparatus 19.1 Laboratory pH Meter—See 10.1. 19.2 Glass Electrode—See 10.2. 19.3 Reference Electrode—See 10.3. \9.4 Temperature Compensator—See 10.4. 19.5 Process pH Measurement Instrumentation—Instru­

ments that are used for process pH measurements are generally much more rugged than those which are used for very accurate measurements in the laboratory.

19.5.1 Electrode Chamber—For process pH measure­ments; the electrodes and thermocompensator are mounted in an electrode chamber or cell.

19.5.1.1 Flow-Through Chamber completely encloses the electrodes and the sample is piped to and from the chamber in a flow-through configuration. Commercially available chambers generally can tolerate temperatures as high as 100°C over a pH range from 0 to 14, and pressures up to 1034 kPa (approximately 150 psi).

19.5.1.2 Immersion Type Chamber, suitable for measure­ment in open streams or tanks, shields but does not completely enclose the electrodes. Immersion-style chambers are available for use at depths to 30 m (100 ft).

19.5.2 Signal Transmission—The glass electrckle is usu­ally a high-impedance device from which only an extremely small current can be drawn. Shielded cable must be used to connect the electrode to the pH analyzer. The signal can frequently be transmitted up to 300 m (approximately 1000 ft) with no loss in accuracy if the manufacturer's recommen­dations are followed carefully. However, long runs are vulnerable to electrical noise pickup and high impedance signal leakage. The signal is usually amplified for distances greater than 5 m (approximately 16 feet).

19.5.3 pH Signal Retransmission—The electrical output signal of on-line pH instrumentation shall be electrically isolated from the electrode measuring circuit to prevent ground loop problems when measuring pH in a grounded sample and connecting the output signal to a computer,

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FIG. 1 Interiaboratory Precision for pH of Aqueous Buffer Solutions

control system, data acquisition system, or other grounded equipment.

20. Reagents 20.1 Commercial Buffer Solutions—CoTaraemdSXy avail­

able prepared buffer should be adequate for the standardiza­tion in Test Method B. These commercial buffer solutions usually have pH values near 4, 7, arid 10, the exact pH and use temperature being provided by the purveyor of the specific buffer. The pH 10 buffer is especiaUy susceptible to contamination from atmospheric carbon dioxide, and fre­quently used or partially filled bottles are particularly vulner­able to this error.

20.2 For more information on reagents, see Section 11.

21. Standardization of Assembly 21.1 Turn on the analyzer, aUow it to warm up thor­

oughly in accordance with the manufacturer's instructions. Wash the electrodes, the thermocompensator, and the sample container with three changes of water or by means of flowing stream from a wash bottle. Form a fresh hquid junction if a sleeve reference electrode junction is used. If manual temperature compensation is to be used, note the

temperature of the water sample and adjust the temperature dial of the meter to corresporid.

21.2 Direct Standardization: 21.2.1 Select two reference buffer solutions that have pfi,

values that bracket the anticipated pH of the water sample. Warm or cool the reference solution to within 2°C of the temperature of the water sample.

21.2.2 Fill the sample container with the first reference buffer solution and immerse the electrodes. Set the known pHj of the reference buffer solution according to the instru­ment manufacturer's instructions. Repeat with successive portions of the reference buffer solution until two successive instrument readings are obtained which differ from the pHs

T A B L f 4 Detemtinat ion of Bias

Rial + •!.* Statistically Significant (95 % Confidence LeveQ

pH Expected pH Found

3.714 6.517 8.147 8.470

3.73 6.53 8.19 8.45

-hO.48 . +0.20 +0.53 -0.24

No Yes Yes Yes

'' Since pH is a logarithmic function, this value may be misleading. It may be more useful to calculate bias as ttie difference between ttie values for pH Expected and pH Found.

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value of the buffer solution by no more than 0.02 pH unit. 21.2.3 Wash the electrodes and sample container three

tiroes with water. Place the second reference buffer solution in the sample container, and measure the pH. Adjust the slope control only until the reading corresponds to the temperature corrected value of the second reference buffer solution. Use additional portions of the second refereiice buffer solution, as before, until two successive readings differ by not more than 0.02 pH unit.

21.2.4 If only an occasional pH determination is made, standardize the assembly each time it is used. In a long series of measurements, supplement initial and final standardiza­tions by interim checks at regular intervals. As commercially available pH assembUes exhibit different degrees of measure­ment stability, conduct these checks at intervals of 30 min, unless it is ascertained that less frequent checking is satisfac­tory to ensure performance. For continuous on-Une mea­surements, the frequency of caUbration shall be determined by experience since it is highly apphcation dependent.

2\.'i Indirect Standardization: 21.3.1 This procedure is to be employed when it is not

convenient or practical to remove the electrodes from the flowing stream or container on which the pH is being determined. Use of a laboratory pH meter or an additional analyzer is required.

21.3.2 Standardize the laboratory pH meter or additional process analyzer as outlined in 21.2.

21.3.3 Collect a grab sample of the water from the immediate vicinity of the electrodes or from the discharge of a flow-through chamber. Measure the pH of this grab sample immediately, using the standardized laboratory pH meter.

21.3.4 Adjust the standardization control on the process analyzer until the reading corresponds to the pH of the grab sample. Repeat the grab samphng, analyzing, and adjusting procedure until two successive readings are obtained that differ by no more than 0.05 pH unit or within an acceptable accuracy.

NOTE 3—Indirect standardization as described above cannot be employed when the pH of the water being tested fluctuates by more than 0.05 pH unit. The standardization shall be accomplished in the shortest possible time if the pH is fluctuating. It is absoliitely essential that the grab sample be representative of the water in contact with the electrodes of the analyzer being standardized. The integrity of the grab sample shall be maintained iintil its pH has been measured by the standardized meter, and its temperature shall remain constant. An alternate proce­dure giving greater flexibility is available using commercially-available process analyzers which provide a hold fiinction. This function is manually activated at the time a grab sample is taken. It holds the pH value on the display, and allows time for the grab sample to be measured

and its value to be used for calibration. After this standardization, the hold feature is deactivated.

21.3.5 Indirect standardization is a one-point calibration and does not establish the proper response of the electrodes over a pH range.

22. Procedure, Batch Samples 22.1 Standardize the assembly as described in 21.2 and

wash the electrodes with three changes of water or by means of a flowing stream from a wash bottle.

22.2 Place the water sample in a clean glass beaker provided with a thermometer and a stirring bar. Stir during the period of pH riieasureriient at a rate that will prevent splashing and that will avoid loss or gain of acidic or basic gases by interchange with the atmosphere. When necessary, stir briskly enough to intermix the phases of a nonhomogen­eous water sample.

22.3 Insert the electrodes and determine a prehminary pH value (the reading may drift). Measure successive portions of the water sample until readings on two successive portions differ by no more than 0.05 pH unit. Two portions will usually be sufficient if the water is well-buffered.

22.4 Record the pH and temperature of the sample.

NOTE 4—Continuous Determination of pH—Make the selection of the electrodes and the electrode chamber to suit the physical and chemical characteristics of the process water. Locate a submersion style electrode chamber so that firesh representative sampling is provided continuously across the electrodes. Agitation may be required to improve homogeneity. Process f)H measurements generally employ automatic temperature compensation. The pH value is usually displayed continuously and can be noted at any specific time. Also, record the successive pH values frequently to provide a permanent record. If the temperature of the sample fluctuates significantly with time, the temperature should also be recorded to interpret the pH values correctly.

23. Report

23.1 Report the temperature of measurement to the nearest TC.

23.2 Report the pH to the nearest 0.1 pH unit.

24. Precision and Bias* 24.1 Because of the wide variability in measurement

conditions and the changeable character of the pH of many process waters, the precision of this test method is probably less than that of Test Method A; however, a precision of 0.1 pH unit should be attainable under controlled conditions.

24.2 Precision and bias data were obtained using buffer solutions only. It is the user's responsibility to assure the vahdity of this test method for untested types of water.

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APPENDIX

(Nonmandatory Infonnation)

XI. MISCELLANEOUS NOTES ON GLASS ELECTRODE MEASUREMENTS AND EQUIPMENT

XI.l Meaning of tbie Term pH XI. 1.1 The term pH historically has referred to the

hydrogen ion activity of a solution and has been expressed as the logarithm to the base 10 of the reciprocal (negative logarithm) of the activity of hydrogen ions at a given temperature, as follows:

pH = log l/(^^-) =- log( / /+)

where: {H'^) = activity of hydrogen ions.

X1.1.2 Although this expression is helpful in giving theo­retical meaning to the term pH and can be used as an approximate definition, it may not be rigorously related to empirical pH measurements. The definition given in 3.2.1 has gained wide acceptance.

XI .2 Temperature Effects XI.2.1 The effects of temperature on electrometric pH

measurements arise chiefly from two sources: (7) tempera­ture effects that are common to all electrometric measure­ments and (2) variations of sample pH with temperature. The first category includes the effect of temperature on the factor /'/2.3026 RT that occurs in the definition of pH (see 3.2). Values of this factor for various temperatures are given in Table 1. When electrodes are moved from a solution at one temperature to a solution at another, time is required for internal reference elements to reach the new temperature and, if saturated solutions are involved (for example, calomel or silver chloride electrodes), for the elements to come to a new equilibrium. During this period, some drifting may be observed. The extent of the problem will depend on the nature of the reference elements and their location within the electrodes.

XI.2.2 Secondly, because of changes in activity coeffi­cients and equilibrium constants with temperature, the pH of a sample will change with temperature. These changes are independent of the method of measurement. In general, the rate 6f change of pH with temperature is not constant, and it may be positive or negative. The data in Table 2, showing changes in pH, of buffer solutions with temperature, are typical examples. Process samples with known temperature coefficients may take advantage of solution temperature compensation available on some process analyzers to pro­vide readout of pH referenced to 25''C.

X I 3 Reference Electrodes XI.3.1 In making pH measurements with the glass elec­

trode, the reference electrode used to complete the cell assembly functions simply as a source of reproducible potential. The absolute value of the reference electrode potential is of no consequence owing to the way the measurements are made. Saturated calomel, silver/silver chloride, and iodide-iodine redox references are all widely

used and have proven themselves to be satisfactory reference electrodes at normal room temperatures. The calomel is the least satisfactory at elevated temperatures, and the iodide-' iodine is the least affected by changing temperatures. De­pending on the environmental conditions, other electrodes may serve satisfactorily as reference eleictrodes.

XI.3.2 If a saturated calomel electrode is used under significantly changeable temperature conditions, care must be taken to see that sufficient soUd potassium chloride is present at all the temperatures to ensure solution saturation throughout, both in the free solution in the electrode tube and in the solution permeating the electrode element. The electrode must be given 5 or 10 min to accommodate itself to a new temperature condition before a pH measurement is made. If the temperature falls appreciably, crystallization of potassium chloride may cause plugging of the Uquid junc­tion; one result may be high resistance and false or erratic potential at the junction. Any such accumulation of potas­sium chloride should therefore be removed by aqueous washing.

XI.3.3 Reference electrodes of the unsaturated type have been used preferentially in continuous mechanized pH monitoring where the temperature is hkely to fluctuate. The selected potassium chloride concentration is freqtiently satu­ration at the lowest temperature of use (for example, approximately 3.3 A' for 0°C). Such a reference electrode has the advantage of being free from the annoying effects caused by variable solubility, but take considerable care to prepare the required concentration and to maintain the prescribed value under plant operating conditions. Follow the instru­ment manufacturer's recommendations on choosing and maintaining reference electrodes.

XI.3.4 Reference electrodes are available with any number of means to estabUsh the Uquid junction. These include, but are not Umited to, dependence on the porosity of wood, fibrous materials, glass-encased noble metal, ground-glass sleeves, ceramic frits, and nonflowing poly­meric bodies. Most offsets and fluctuations in readings as a result of stirring are due to effects at the Uquid junction of the reference electrode.' For laboratory use, cleanable junc­tions (usually of a sleeve type of construction or having renewable elements) will give more consistent performance in "dirty" samples.

XI.4 Faulty Glass Electrode Response and Restorative Techniques

XI.4.1 Detecting Faulty Electrodes—The pH measuring assembly is standardized with two reference buffer solutions (see 12.2) to verify the linearity of response of the electrode

' Brezinski, D. P., "Kinetic, Static and Stirring Errors of Liquid Junction Reference Electrodes," The Analyst, 1983, 108, 425.

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combination at different pH values. Standardization also detects a faulty glass or reference electrode or an incorrect temperature compensator. The faulty electrode is indicated by a failure to obtain a reasonably correct value for the pH of the second reference buffer solution after the meter has been standardized with the first. A cracked glass electrode will often yield pH readings that are essentially the same for both standards and should be discarded. Even though a normal glass electrode responds remarkably weU to moderate pH changes, it is not necessarily a perfect pH-measuring device; and may miss the rigid requirements of 12:2, if, for example, the pH span is made as great as 5 pH units (phthalate to borax). • ' • . - .• S . • • . - • . .

X1.4.2 Imperfect pH Response—-The pH response of the glass electrode may be impaired by a few coating substances (certain oily materials or even some particulates). When the faulty condition is disclosed by the check with the two reference buffer solutions, the electrode can frequently be restored to normal by an appropriate cleaning procedure.

XI.4.3 Stirring Errors—If readings drift or are noisy only when the solution is stirred, there are two Ukely caiises: (7) the sample is poorly buffered, and the pH is affected by air or CO2 or (2) the reference junction is clogged or malfunc­tioning.

XI.4.4 Glass Electrode Cleaning Techniques—Where emulsions of free oil and water are to be measured for pH, it is absolutely necessary that the electrodes be cleaned thor­oughly after each measurement. This may be done by washing with soap or detergent and water, followed by several rinses with water, after which the lower third of the electrodes should be immersed in HCI (1+9) to remove any film that may have been formed. Rinse the electrode thoroughly by washing it in several changes of water before returning it to service. Process pH analyzers used for continuous measurement may be provided with an ultra­sonic cleaner to lessen or even eliminate the need for manual cleaning of electrodes.

XI.4.5 Thorough cleaning with a suitable solvent may be necessary after each measurement if the sample contains slickly soaps or suspended particles. If this fails, a chemical treatment designed to dissolve the particular deposited coating may prove successful. After the final rinsing of the electrode in the cleaning solvent, immerse the lower third of the electrodes in HQ (1-1-9) to remove a possible residual

film. Wash the electrode thoroughly in several changes of water before subjecting it to the standardization procedure.

XI.4.6 Protein coatings may be removed by a 1 to 2 min soak of the bulb in a 30% solution of a commercial hypochlorite bleach (approximately 1.5 % NaOQ). This should be followed by a rinse in 1-1-9 HQ:water and thorough washing with water.

X1.4;7 If an electrode has failed to respond to the treatment suggested in XI.4.3, try a more drastic measure as a last resort. This drastic treatment, which will Umit the Ufe of the electrode and should be used only as an alternative to discarding it, is immersing it in chromic acid cleaning solution for a period of several minutes (or longer if necessary). Chromic acid is particularly effective in cleaning foreign substances from the surface of the glass, but it also has a dehydrating effect on the glass. Consequently allow an electrode so treated, after thoroughly rinsing, to stand in water overnight before using it for measurements. Finally, if the electrode fails to respond to the chromic acid solution, it may be subjected to mild etching in ammonium bifluoride solution. Immerse the electrode for about 1 min in a 20 % solution of ammonium bifluoride (NH4HF2) in water, in a polyethylene cup. The bifluoride actuaUy removes a portion of the bulb glass, and should be used only as a last resort (and then only infrequently). Follow the fluoride etch by thorough rinsing and conditioning as is recommended for a new electrode. The electrode manufacturer may have additional suggestions, specific to his own product.

XI.4.8 Techniques for cleaning flow cell electrodes in­clude the use of ultrasonics, brushes, and high-velocity submerged jets.

XI .5 Special Measurements Techniques XI.5.1 Measurements on Alkaline Waters—Although

most modem pH glass formulations give good results in alkaline solutions, there can be an error if the solution is quite alkaUne and contains high levels of sodium. This effect is greater at elevated temperatures. If in doubt, check with the electrode manufacturer.

XI.5.2 Carbon dioxide from the air tends to react with an alkaUne water and to change its pH. Make all measurements with alkaline waters or buffer solutions as quickly as possible, with the water exposed to the air no longer than is absolutely necessary.

The American Society for Testing and Materials takes no position respecting the validity ol any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.

This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should tie addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a lair hearing you should make your views known to the ASTM ciommittee on Standards, 100 Barr Hartx)r Drive, West Conshohocken, PA 19428.

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Attachment 6

Calibration SOPs

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Note: SOP 15 cited within.

STANDARD OPERATING PROCEDURE

CALIBRATING THE SPECIFIC CONDUCTANCE METER SOP 87

In general, the specific conductance meter is not calibrated. However, measuring the specific conductance of a standard prior to measuring a sample confirms that the meter is responding consistently. In addition, the meter performs an automatic temperature correction. The following procedure should be followed prior to measuring the specific conductance of a sample:

1. Inspect the electrode to determine if it is clean and shiny. If not, polish the electrode with a wet piece of 1500-grit sand paper.

2. Rinse the probe with deionized water.

3. Place the electrode in a 100-/jS/cm standard.

4. With the specific conductance meter in temperature mode, determine the temperature of the standard.

5. Change modes to specific conductance, making sure the switch at the top of the instrument is on "auto temperature correct, 25°C." Adjust the dial at the bottom of the instrument to reflect the measured tem­perature of the standard (if this dial is not present, this adjustment is automatically performed by the instrument).

6. Record the specific conductance of the 100-/jS/cm standard.

7. Place the electrode in the l,000-/iS/cm standard, and record the spe­cific conductance.

Measure the specific conductance of the sample according to either the instrument operat­ing manual or SOP 15.

July 1996 87-1 \\enterprise\docs\sops\sop.87.dx

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Boulder Laboratory Balance Calibration SOP EBL1 (Version 1.0)

General

The Boulder laboratory operates two Denver Instrument balances, located in the analytical lab. The 3000 XE balance is used for weighing samples with masses up to 3000 grams and is accurate to 0.1 grams. The lOOA analytical balance is capable of measuring samples up to 100 grams with an accuracy of 0.0001 grams.

In order to maintain accuracy of these instruments, it is imperative that they not be moved between calibrations. The balances should be calibrated every month, or if not used for several months (i.e. if the lab is not in use), prior to beginning an experiment. The balances should be plugged in at all times. If a balance is unplugged, it will need time to warm up and re-equilibrate after being plugged in. This may take.up to 24 hours before the instrument can be calibrated. Lab personnel are responsible for checking the calibration logbook when starting experiments that use the balances. All calibrations for the balances should be documented in the "Balance Calibration" book, located in the drawer under the balances. Persons calibrating the lab equipment are required to document the following information in the calibration book:

• Signature of the person performing the calibration

• Date of calibration

• Balance model number

• The weight the balance was calibrated to.

Copies of this documentation can be obtained from the lab manager. Calibration records will be archived for a minimum of two years. To determine the most current version of this SOP, consult the laboratory manager who has on file the master tracking list for this SOP. The master tracking list documents all changes and updates to this SOP. This SOP will be reviewed and updated annually. AH updates will be reviewed and approved by the Office Director and/or Regional Manager.

The calibration weights are located in the lab office in the locked filing cabinet. The calibration weights sets were purchased from Fisher Scientific and meet standards for ANSI/ASTM Class 1 calibration weights.

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The following step-by-step procedures shall be used to calibrate each balance:

Denver Instruments 3000 XE Calibration;

• Clean the pan using the scale brush.

• Tare the balance.

• Obtain the brass calibration weights (large box) from the 2°** drawer of the locking file cabinet in the laboratory office.

• Press and hold the 'Tare" button until the display reads "Calibrate."

• Place 2000 grams (all weights) on the balance pan. When handling the weights, use powder free latex gloves and never place the weights on the counter.

• When the balance stabilizes at the proper weight, remove the calibration weights and place in the box.

• Tare the balance.

• Place the weights (2000 grams) on the balance to verify that the balance is calibrated.

• If the mass of the calibration weights is different from the actual mass by 0.1 grams, then repeat the calibration procedure until the balance is accurately calibrated. If the calibration fails after three attempts, contact the laboratory manager as the balance may need to be serviced. In the event the instrument needs servicing, the scale should be sent to Denver Instruments.

• Document the calibration in the Balance Calibration book.

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Denver Instruments 100 A Calibration:

• Clean the pan using the balance brush.

• Check the bubble level on the base of the balance to confirm if it is

level. Adjust it if needed.

• Obtain the stainless steel calibration weights (small box) from the 2°''

drawer of the locking file cabinet in the laboratory office.

• Tare the balance.

• Press and hold the "Tare" button until the display reads "Calibrate."

• Using the tweezers (do not touch this weight with your fingers or place

on the counter), place the 100 gram weight onto the weighing pan.

• Wait until the display stabilizes at 100 grams, remove the calibration

weight and place it into the box.

• Tare the balance.

• Place the weight on the balance to verify the calibration.

• If the display reads a difference in the weight greater than 0.0001

grams, than repeat the calibration procedure until the balance is

calibrated. If the calibration fails after three attempts, contact the

laboratory manager as the balance may need to be serviced. In the

event the instrument needs servicing, the scale should be sent to

Denver Instruments.

• Document the calibration in the Balance calibration book.

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