iso-tc147-sc2 n1474 sc2wg52 n 76 proposal new project arseni

ISO/TC 147/SC 2 N 1474

ISO/TC 147/SC 2Physical, chemical and biochemical methods

Email of secretary: [email protected] Secretariat: DIN (Germany)

SC2WG52 N 76 Proposal New project Arsenic species HPLC HG-AFS

Document type: Working draft

Date of document: 2015-03-27

Expected action: INFO

Background: Dear member, Enclosed please find a proposal for the new project "Water quality - Determination of four chemicalarsenic species - Method using high performance liquid chromatography (HPLC) with hydridegeneration atomic fluorescence spectrometry (HG-AFS)". This draft will be discussed at the meeting of SC 2/WG 52 "Antimony, arsenic and selenium" inConshohocken, Philadelphia, USA 2015-06-01. Best regards Gabriela Barz

Committee URL: http://isotc.iso.org/livelink/livelink/open/tc147sc2

FORM 4 (ISO) v. 2013 Page 1 of 4

Proposal for a new project

Closing date for voting

Reference number (to be given by the Secretariat)

Date of circulation ISO/TC 147/SC 2/WG 52 N 76 (replaces Doc WG 52 N 75) Secretariat

For discussion at the meeting of SC 2/WG 52 in Conshohocken, Philadelphia, USA, 2015-06-01; Point 6 of the agenda

IMPORTANT NOTE: Proposals without adequate justification risk rejection or referral to originator. Guidelines for proposing and justifying a new work item are contained in Annex C of the ISO/IEC Directives, Part 1.

The proposer has considered the guidance given in the Annex C during the preparation of the NWIP. Proposal (to be completed by the proposer)

Title of the proposed deliverable. (in the case of an amendment, revision or a new part of an existing document, show the reference number and current title)

English title Water quality - Determination of four chemical arsenic species - Method using high performance liquid chromatography (HPLC) with hydride generation atomic fluorescence spectrometry (HG-AFS)

French title (if available)

Qualit de l'eau - Dtermination de quatre formes chimiques de larsenic Mthode par chromatographie liquide haute performance (CLHP) avec spectromtrie de fluorescence atomique gnration d'hydrures (HG-AFS)

Scope of the proposed deliverable. The proposed standard will specify a method for the determination of four arsenic species dissolved in waters intended for human consumption, such as surface waters, groundwaters and rainwaters. The working linear dynamic range is dependent on the operating conditions; under standard conditions, it ranges from 1 g/l to 50 g/l for the four species in question. It will use a simple relatively low-cost filter atomic fluorescence for detection of the various arsenic hydride species



Purpose and justification of the proposal* In the environment, metals and metalloids are found in the form of various chemical species. Chemical speciation makes it possible to identify and quantify these different species. For the same metal or metalloid, given that the toxicity of each compound may vary significantly, it can be very useful to quantify each of the significant toxicological arsenic species present in a given sample. The proposed method is applicable to the determination of arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). In natural water samples, according to the literature, the main arsenic species encountered are arsenite and arsenate. However, the organic arsenic species MMA and DMA may also be encountered in some surface waters. For arsenic, the toxicity of these arsenic species varies considerably; inorganic species are recognized as being more toxic than organic species and, the toxicity of As III is greater than that of As V. The proposed method is applicable to the determination of As(III), As (V), MM and DMA. All current ISO and CEN arsenic in waters standards can only determine "total arsenic". The proposed new standard method will provide results for all of the four arsenic species given above. This information can be very useful for selecting and optimising the appropriate removal of arsenic technique for treating groundwaters containing unacceptable levels of naturally occurring arsenic. The setting up and routine running of proposed robust speciation method should be within the capability of any competent drinking water analysis laboratory It is hoped to be able to find an adequate number of laboratories to carry out a method validation trial. It should be noted that arsenic is one of WHOs 10 chemicals of major public health concern. See also: - http://www.who.int/mediacentre/factsheets/fs372/en/ and

http://www.sustainablefuture.se/arsenic/towards_effective.html *The reason for requiring justification statements with approval or disapproval votes is primarily to collect input on market or stakeholder needs, and on market relevance of the proposal, to benefit the development of the proposed ISO standard(s). Any NSB vote in relation to a proposal for new work may result in significant commitments of resources by all parties (NSBs, committee leaders and delegates/experts) or may have significant implications for ISO's relevance in the global community. It is especially important that NSBs consider and express why they vote the way they do. In addition, it is felt that it would be useful for ISO and its committees to have documentation as to why the NSBs feel a proposal has market need and market relevance. Therefore, please ensure that your justifying statements with your approval or disapproval vote convey the reason(s) why your national consensus does or does not support the market need and/or global relevance of the proposal.

If a draft is attached to this proposal,:

Please select from one of the following options (note that if no option is selected, the default will be the first option):

Draft document will be registered as new project in the committee's work programme (stage 20.00) Draft document can be registered as a Working Draft (WD stage 20.20) Draft document can be registered as a Committee Draft (CD stage 30.00) Draft document can be registered as a Draft International Standard (DIS stage 40.00)

Is this a Management Systems Standard (MSS)? Yes No

NOTE: if Yes, the NWIP along with the Justification study (see Annex SL of the Consolidated ISO Supplement) must be sent to the MSS Task Force secretariat ([email protected]) for approval before the NWIP ballot can be launched.

Indication(s) of the preferred type or types of deliverable(s) to be produced under the proposal.

International Standard Technical Specification Publicly Available Specification Technical Report

Proposed development track 1 (24 months) 2 (36 months - default) 3 (48 months)

Known patented items (see ISO/IEC Directives, Part 1 for important guidance)

Yes No If "Yes", provide full information as annex



A statement from the proposer as to how the proposed work may relate to or impact on existing work, especially existing ISO and IEC deliverables. The proposer should explain how the work differs from apparently similar work, or explain how duplication and conflict will be minimized. This will be a lower cost alternative method to the CD Water quality Determination of four chemical arsenic species Method using high-performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS)

A listing of relevant existing documents at the international, regional and national levels. Currently there are no ISO or CEN standards relating to arsenic speciation using atomic spectroscopic detection. However there is a Draft TS 19620 using the much more costly ICP-MS detection technique

A simple and concise statement identifying and describing relevant affected stakeholder categories (including small and medium sized enterprises) and how they will each benefit from or be impacted by the proposed deliverable(s) There is an inceasing demand for arsenic speciation analysis as the toxicity of arsenic cannot simply be determined by carrying out a total arsenic analysis. Almost certainly regulators will be looking to set requirements for specific arsenic species. Also, the efficiency of arsenic removal processes from groundwater is affected by the arsenic speciation and this analysis is required for optimisation of this key process Liaisons: A listing of relevant external international organizations or internal parties (other ISO and/or IEC committees) to be engaged as liaisons in the development of the deliverable(s).

Joint/parallel work: Possible joint/parallel work with:

IEC (please specify committee ID) CEN (please specify committee ID) TC 230 Other (please specify)

A listing of relevant countries which are not already P-members of the committee.

Preparatory work (at a minimum an outline should be included with the proposal) A draft is attached An outline is attached An existing document to serve as initial basis

The proposer or the proposer's organization is prepared to undertake the preparatory work required Yes No

Proposed Project Leader (name and e-mail address) K. Clive Thompson (Convenor of ISO/TC 147/SC 2/WG 52) [email protected]

Name of the Proposer (include contact information) K. Clive Thompson [email protected] (NSB: BSI)

Supplementary information relating to the proposal This proposal relates to a new ISO document; This proposal relates to the adoption as an active project of an item currently registered as a Preliminary Work Item; This proposal relates to the re-establishment of a cancelled project as an active project.

Other:

Annex(es) are included with this proposal (give details) PNWI ISO/WD Arsenic HPLC HG-AFS



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ISO 2015 All rights reserved

Document type: International Standard Document subtype: Document stage: (20) Preparatory Document language: E

ISO/TC 147/SC 2 N 1474 Date: 2015-03-26

PNWI ISO/WD Arsenic HPLC HG-AFS

ISO/TC 147/SC 2/WG 52 N 76

Secretariat: DIN

Water quality Determination of four chemical arsenic species Method using high performance liquid chromatography (HPLC) with hydride generation atomic fluorescence spectrometry (HG-AFS) Qualit de l'eau Dtermination de quatre fromes chimiques de l'arsenic Mthode par chromatographie liquide haute performance (CLHP) avec spectromtrie de fluorescence atomique gnration d'hydrures (HG-AFS)

Warning

This document is not an ISO International Standard. It is distributed for review and comment. It is subject to change without notice and may not be referred to as an International Standard.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation.


ii ISO 2015 All rights reserved

Copyright notice

This ISO document is a working draft or committee draft and is copyright-protected by ISO. While the reproduction of working drafts or committee drafts in any form for use by participants in the ISO standards development process is permitted without prior permission from ISO, neither this document nor any extract from it may be reproduced, stored or transmitted in any form for any other purpose without prior written permission from ISO.

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Violators may be prosecuted.


ISO 2015 All rights reserved iii

Contents Page

Foreword ............................................................................................................................................................ iv Introduction ......................................................................................................................................................... v 1 Scope ...................................................................................................................................................... 1 2 Normative references ............................................................................................................................ 1 3 Terms and definitions ........................................................................................................................... 2 4 Principle.................................................................................................................................................. 3 5 Interferences .......................................................................................................................................... 3 6 Apparatus ............................................................................................................................................... 3 7 Reagents and standards ....................................................................................................................... 4 8 Sampling, preservation and storage of drinking, surface and ground water samples .................. 6 9 Procedure ............................................................................................................................................... 7 10 Expression of results ............................................................................................................................ 8 11 Test report .............................................................................................................................................. 8 Annex A (informative) Example - Layout of LC-HG-AFS ................................................................................. 9 Annex B (informative) Example of experimental conditions ........................................................................ 10 Bibliography ...................................................................................................................................................... 15


iv ISO 2015 All rights reserved

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO Arsenic HPLC HG-AFS was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical and biochemical methods.


ISO 2015 All rights reserved v

Introduction

In the environment, metals and metalloids are found in the form of various chemical species. Chemical speciation makes it possible to identify and quantify these different species. For the same metal or metalloid, given that the toxicity of each compound may vary significantly, it can be useful to quantify each of the species present in a given sample. For arsenic, the toxicity of the various species varies considerably; inorganic species are recognized as being more toxic than organic species and, for example, the toxicity of As(III) is greater than that of As(V). The proposed method is applicable to the determination of arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA).

In natural water samples, according to the literature, the main arsenic species encountered are arsenite and arsenate. However, the organic species MMA and DMA may also be encountered in surface waters. Arsenobetaine and other organic arsenic species are not present in natural water samples and are therefore not included in this method.

WORKING DRAFT PNWI ISO/WD Arsenic HPLC HG-AFS

ISO 2015 All rights reserved 1

Water quality Determination of four chemical arsenic species Method using high performance liquid chromatography (HPLC) with hydride generation atomic fluorescence spectrometry (HG-AFS)

WARNING Persons using this document should be familiar with normal laboratory practice. This document is not intended to cover any safety problems associated with its use, if applicable. It is the responsibility of the user to establish appropriate safety and health methods and to ensure compliance with any national regulatory conditions.

IMPORTANT It is absolutely essential that tests conducted in accordance with this document be carried out by suitably qualified staff.

1 Scope

This International Standard specifies the determination of four arsenic species dissolved in waters intended for human consumption, surface waters, ground waters and rain waters. The working linear dynamic range is dependent on the operating conditions; under standard conditions, it ranges from 0,1 g/l to 50 g/l for the four species in question. Samples containing arsenic at concentrations higher than the linear dynamic range can be analysed after suitable dilution.

The sensitivity of this method is dependent on the instrument operating conditions selected. The limit of quantification of the method (LOQ) is also dependent on the operating conditions of the analytical system used and the extent of the calibration range used. The limits of quantification (LOQ) are given as examples in Annex B, and are between 0,1 g/l and 0,4 g/l. This information is given as an indicative guide.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 3696, Water for analytical laboratory use Specification and test methods

ISO 5667-1, Water quality Sampling Part 1: Guidance on the design of sampling programmes and sampling techniques

ISO 5667-3, Water quality Sampling Part 3: Preservation and handling of water samples

ISO 17378-1, Water quality Determination of arsenic and antimony Part 1: Method using hydride generation atomic fluorescence spectrometry (HG-AFS)

ISO 17378-2, Water quality Determination of arsenic and antimony Part 2: Method using hydride generation atomic absorption spectrometry (HG-AAS)


2 ISO 2015 All rights reserved

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.1 analyte element to be determined

[SOURCE: ISO 17294-1:2004, 3.2]

3.2 blank calibration solution solution prepared in the same way as the calibration solution but leaving out the analyte

[SOURCE: ISO 17294-1:2004, 3.3]

3.3 calibration solution solution used to calibrate the instrument, prepared from (a) stock solution(s) or from a certified standard

3.4 stock solution solution with accurately known analyte concentration(s), prepared from suitably pure chemicals

[SOURCE: ISO 17294-1:2004, 3.30]

3.5 test sample sample prepared from the laboratory sample, for example by grinding or homogenizing

[SOURCE: ISO 17294-1:2004, 3.31]

3.6 determination (Remark from SC 2 secretariat: This term is of very general nature; could be precised?) entire process from preparing the test sample solution up to and including measurement and calculation of the final result

3.7 linearity straight line relationship between the result of measurement (signal) and the quantity (concentration) of the analyte to be determined

Note 1 to entry: Or straight line relationship between the (mean) replicate results of measurement (signal) and the quantity (concentration) of the component to be determined.

(Request from SC 2 secretariat: Kindly check the ISO Online Browsing Platform, whether definition text could be adapted to already existing definitions)

3.8 limit of quantification (LOQ) lowest concentration of an analyte that can be determined with a specified degree of accuracy and precision

(Please check ISO OBP)



4 Principle

The different arsenic species are separated using a specific column in a high-performance liquid chromatograph (HPLC). The separation of arsenic species in natural water is typically achieved using strong anion exchange ion chromatography. On elution form the column the arsenic species are acidified and subsequently reduced using a sodium tetrahydroborate reductant to form the species specific covalent gaseous hydride. After gas liquid separation the arsenic hydride species are delivered to an atomizer such as hydrogen diffusion flame or heated quartz cuvette using an argon carrier gas. Moisture is removed from this stream using a hygroscopic NafionTM membrane dryer. After atomisation the arsenic is determined by atomic fluorescence spectrometry (AFS) equipped with an Arsenic boosted discharge hollow cathode lamp. Atomic absorption and other detection methods with hydride generation can be used provided that the performance specification of the method is achieved.

The concentration of arsenic is determined by comparing the quantity of atomic arsenic detected in the sample in relation to the calibration solutions of each species.

Annex A presents a block diagram of the measurement apparatus.

5 Interferences

The hydride generation technique is prone to interferences by transition and easily reducible metals. For the majority of natural water samples, this type of interference should not be significant. The user should carry out recovery tests on typical waters and also determine the maximum concentrations of potentially interfering elements, using appropriate methods. If such interferences are indicated, the level of interferences should be assessed by performing spike recoveries. However, the atomic fluorescence technique has a high linear dynamic range and a very low detection limit. In most cases interferences can be removed by a simple dilution step as long as the final arsenic concentrations are above the LOQ. It is important that the excitation source does not contain any significant amount of other hydride-forming elements (e.g. antimony when analysing for arsenic or arsenic when analysing for antimony) that emit fluorescent radiation over the band pass of the interference filter used in the detector, if these elements are present in the sample.

6 Apparatus

6.1 General

Due to significant differences between the various instrument models and brands available, it is not possible to give detailed instructions on their operation. The operator should thus refer to the instructions provided by the manufacturer of each instrument.

Usual laboratory glassware and equipment and, in particular, the following:

6.2 Hydride generation, including a peristaltic pump unit to deliver reagents and load sample injection loop, mixing manifold to produce covalent hydride species, gas-liquid separator to separate hydride species from liquid phase reagents and moisture removal device.

NOTE The concentration and flow of reagents are specifically related to the hydride generation apparatus. The user should use optimal conditions to ensure that best analytical performance is obtained.

((Remark from SC 2 secretariat: "Should" forms a requirement, which is not allowed in Notes; to be rephrased or to be changed to normal text))

6.3 High-performance liquid chromatograph (HPLC), including a column for analyte separation and optionally a chromatographic pre-column. The HPLC system is optionally equipped with an in-line degassing system and injection system for introducing the sample. In most cases an isocratic pump can be used although the use of gradient pumps to provide optimal separation times is permitted.



6.4 Sample changer

It is recommended that the HPLC system should be coupled with a sample changer.

NOTE Various column/eluent pairings can be used for separating arsenic species. Some examples are described in Annex B.

6.5 Vacuum filtration system, for filtering the eluent and reagents prepared.

7 Reagents and standards

7.1 General requirements

All reagents shall be of known analytical grade. The concentration of the analyte or interfering substances in the reagents and water should be negligible compared to the lowest concentration to be determined (LOQ for example).

NOTE Standard stock solutions are commercially available or can be prepared using chemicals of known analytical purity.

7.2 Deionized water, grade 1, as defined in ISO 3696.

7.3 HPLC grade water

HPLC grade water is used to prepare the mobile phase, the calibration solutions and produce the sample dilutions. It can be prepared by suitably purifying deionized water (7.2).

7.4 Nitric acid (HNO3) = 1,4 g/ml

Acid used at a rate of 0,5 % volume fraction to stabilize the samples for the total arsenic concentration determination.

NOTE Nitric acid is available in the following forms: (HNO3) = 1,40 g/ml (w(HNO3) = 650 g/kg) and (HNO3) = 1,42 g/ml (w(HNO3) = 690 g/kg). These two forms are suitable for use with this method.

7.5 97 % sodium hydroxide, analytical grade.

7.6 1N sodium hydroxide solution

Weigh 4 g of sodium hydroxide pellets (7.5) and pour them into a 100 ml flask. Make up to the mark with deionized water (7.2) and stir until the pellets have completely dissolved.

7.7 Hydrochloric acid (HCl) = 1,18 g/ml

7.8 10 % Hydrochloric acid hydride generation solution

Measure 100 ml of high purity hydrochloric acid (7.7) and carefully add to 900 ml of deionized water (7.2).

7.9 Sodium tetrahydroborate NaBH4, analytical reagent grade pellets.

7.10 1,4 % m/V sodium tetrahydroborate / 0,4 % m/V sodium hydroxide hydride generation solution

Weigh 14 g of NaBH4 pellets (7.9) and transfer to a 1 l flask. Add 4 g of NaOH pellets (7.5) and make up to the mark with deionized water (7.2). Filter if necessary and prepare daily.

7.11 Disodium ethylene diamine tetra-acetate (EDTA), C10H14N2Na2O82H2O (CAS No. 6381-92-6).



7.12 0,2 N EDTA solution

In a 100 ml volumetric flask, dissolve 7,445 g of EDTA (7.11) in approximately 80 ml of water (7.2) and make up to the mark. This solution has a shelf-life of six months.

7.13 Standard substances

As(III): Arsenous oxide As2O3 (CAS No. 1327-53-3)

As(V): Di-sodium hydrogen arsenate Na2HAsO47H2O (CAS No.10048-95-0)

DMA: Dimethylarsinic acid (CH3)2 AsO2Na 3H2O (CAS No. 124-65-2)

MMA: Monomethylarsonic acid CH3AsO(ONa)26H2O (CAS No. 144-21-8)

7.14 Stock solutions

For each of the species, As(III), As(V), DMA and MMA, prepare a stock solution with a concentration = 1 000 mg/l expressed as As.

These solutions are prepared from the standard substances (7.13).

In 100 ml flasks, dissolve the suitable mass of each substance (7.13) as shown in Table 1.

Commercially available stock solutions of the required concentration can also be used.

Table 1 Preparation guidelines for 1 000mg/l arsenic standards

Species Masses to weigh g

Final volume ml

As(III) 0,132 4 ml of 1N NaOH (7.6) made up to 100 ml with water (7.3)

As(V) 0,416 100 ml in water (7.3)

DMA 0,286 100 ml in water (7.3)

MMA 0,390 100 ml in water (7.3)

These solutions, when stored protected from light and at 4 C, are considered to be stable for one year.

The 10 mg/l single-element working solutions are also stable for one year if they are stored protected from light and at 4 C and stabilized in 4 % m/V NaOH (7.6) for As(III).



7.15 Calibration solutions

The calibration solutions are prepared from the 1 000 mg/l stock solutions (7.14). Tables 2 and 3 are given as examples.

Table 2 Preparation guidelines for working arsenic standards

Concentration g/l

Sample volume l

Solution for dilution qs HPLC grade water (7.3)

1 000 100 l of each solution 1 000 mg/l (7.14) As(III), As(V), DMA, MMA

100 ml

5 500 l 1 000 g/l 100 ml

10 1 000 l 1 000 g/l 100 ml

25 2 500 l 1 000 g/l 100 ml

50 5 000 l 1 000 g/l 100 ml

To prepare standard solutions below 5 g/l use the 10 mg/l intermediate stock to produce a mixed standard of 100 g/l. Table 3 is given as an example.

Table 3 Preparation guidelines for working arsenic standards

Concentration g/l

Sample volume l

Solution for dilution qs HPLC grade water (7.3)

100 1 000 l of each solution 10 mg/l (7.14) As(III), As(V), DMA, MMA

100 ml

0.2 200 l 100 g/l 100 ml

0.5 500 l 100 g/l 100 ml

1.0 1 000 l 100 g/l 100 ml

2.0 2 000 l 100 g/l 100 ml

7.16 Eluents

Various eluents can be used and the choice depends on the type of separation column chosen. The eluent compositions described in Annex B and in the associated tables are given as an example.

7.17 HPLC trace analysis grade methanol

8 Sampling, preservation and storage of drinking, surface and ground water samples

Sampling shall be performed in accordance with 5667-1 and ISO 5667-3, using suitable sampling containers, e.g. HDPE or glass.

The preservation technique described in ISO 5667-3 shall only be applied for the total arsenic determination. In ISO 5667-3 it is suggested to preserve samples with HNO3 or HCl at pH



The bibliographic study showed that there were a number of methods to restrict the evolvement of the As(III) and As(V) species. It has been demonstrated that acidifying with 0,1 % m/V HCl, 0,4 % m/V HNO3 or 0,2 % m/V H2SO4 m/V made it possible to keep both species intact at ambient temperature and at 4 C for at least 30 d.

It has also been shown that natural water samples filtered at 0,45 m and stored at 4 C in bottles filled to the rim are stable for 30 d.

In the case of samples of water intended for human consumption with turbidity levels



9.3 Sample measurement

The water samples can be injected with or without dilution depending on the total arsenic concentrations measured previously.

Samples which exhibit retention time shift due to sample matrix should be diluted to overcome the effect if they have sufficiently high arsenic concentrations to fall in the calibration range. Alternatively the retention time shift should be verified by species specific spike additions at similar concentration found.

NOTE 1 The use of a smaller injection volume, e.g. 50 l, will help to overcome retention time shift.

NOTE 2 The preliminary total arsenic analysis on the filtered sample provides information on any dilution required prior to injecting the sample and serves to check the consistency of the results. It is important to ensure that the sum of the species measured remains less than or equal to the total arsenic value measured.

10 Expression of results

The results obtained are expressed as g As/l, applying the dilution factors used for each sample. Give the results within 2 significant digits.

Example:

Arsenic(III) 1,2 g/l

Arsenic(V) 0,5 g/l

11 Test report

The test report shall contain at least the following information:

a) the test method used, together with a reference to this International Standard (PNWI ISO/WD);

b) complete identification of the sample;

c) expression of the results as indicated in Clause 10;

d) any details not specified in this document or considered to be optional, and any particular factor liable to have affected the results.



Annex A (informative)

Example - Layout of LC-HG-AFS

Figure A.1 Layout of LC-HG-AFS

3

4

1

5

2

6 7

8

9

10

11

AUTOSAMPLER

INJECTION VALUE

MOBILE PHASE

LC PUMP

HCL

NaBH4

GLS

AUX H2

NAFION DRYER

AFS

COLUMN

1

2

3

4

5

6

7

8

9

10

11



Annex B (informative)

Example of experimental conditions

Figure B.1 Chromatogram representing four arsenic species containing 5 g/l; As(III), DMA, MMA, and As(V) (order of elution)

Table B.1 HG-AFS conditions

HCl concentration 25 % volume fraction

HCl flowrate 1,7 ml/min

NaBH4 concentration 0,7 % m/V in 0,4 % m/V NaOH

NaBH4 flowrate 5 ml/min

Argon carrier gas flowrate 250 ml/min

Air dryer gas flowrate 2,5 l/min

Aux. hydrogen flowrate Optional (not used in example shown)

Primary current 27,5 mA

Boost current 35,0 mA

Acquisition Peak area

Table B.2 Chromatographic conditions

Flow rate Elution gradient: fixed flow rate at 1 ml/min

Column Hamilton PRP-X 100 (250 mm 4,6 mm) 10 m

Eluent A: 12,5 mM ammonium carbonate at pH 9

B: 60 mM ammonium carbonate at pH 9

Gradient

T = 0 min: 100 % A, 0 % B

T = 2 min: 0 % A, 100 % B

T = 10 min: 100 % A, 0 % B

Injection loop 50 l to 250 l



Table B.3 Calibration conditions

Number of standards Blank + 5 points

Calibration dynamic range 0,5 g/l to 50 g/l 0,2 g/l to 2 g/l

Limit of detection (3n-1 calculated)

0,05 g/l for As(III), As(V), DMA & MMA

Limit of quantification 0,16 g/l for As(III), As(V), DMA & MMA



Same conditions as in Table B.1


Pump Isocratic

Flow rate Isocratic conditions: fixed flow rate at 1 ml/min


Eluent 2,5 mM NaH2PO4 + 0,5 mM 2Na-EDTA + 2,5 % (volume fraction) methanol at pH=6





Limit of detection (calculated)

0,05 g/l for As(III)

0,1 g/l for As(V) and MMA

0,2 g/l for DMA

Limit of quantification

0,16 g/l for As(III)

0,33 g/l for As(V) and MMA

0,66 g/l for DMA




Table B.7 HG-AFS Conditions



Pump Isocratic

Flow rate Isocratic conditions: fixed flow rate at 1 ml/min


Eluent 20 mM (NH4)2HPO4 at pH = 6





Limit of detection (calculated) 0,05 g/l for As(III) and MMA

0,1 g/l for As(V) and DMA

Limit of quantification 0,16 g/l for As(III) and MMA

0,33 g/l for As(V) and DMA







Pump Binary

Flow rate Eluent gradient: fixed flow rate at 1 ml/min


Eluent A: 10 mM (NH4)2HPO4/(NH4)H2PO4 in 3 % methanol at pH = 7

B: 100 mM (NH4)2HPO4 in 3 % methanol at pH = 8,5

Gradient

T = 0 min: 100 % A, 0 % B

T = 3 min: 0 % A, 100 % B

T = 10 min: 100 % A, 0 % B





Limit of detection (calculated) 0,05 g/l for As(III), MMA and As(V)

0,1 g/l for DMA

Limit of quantification 0,16 g/l for As(III), MMA and As(V)

0,33 g/l for DMA







Pump Isocratic

Flow rate Eluent gradient: fixed flow rate at 1 ml/min


Eluent 20 mM NaH2PO4/Na2HPO4 at pH = 6,2





Limit of detection (calculated) 0,05 g/l for As(III) and MMA

0,1 g/l for DMA and As(V)

Limit of quantification 0,16 g/l for As(III) and MMA

0,33 g/l for DMA and As(V)



Bibliography

[1] Cheam, V. and Agemian, H. (1980). "Preservation of inorganic arsenic species at microgram levels in water samples." Analyst 105(1253): pp. 737-743.

[2] Aggett, J. and Kriegman, M.R. (1987). "Preservation Arsenic (III) and Arsenic (V) in samples of Sediment Interstitial water." Analyst 112: pp. 153-157.

[3] E.M. Hall, G., Pelchat, J.C. et al. (1999). "Stability of inorganic arsenic (III) and arsenic (V) in water samples." Journal of Analytical Atomic Spectrometry 14(2): pp. 205-213.

[4] Gallagher, P.A., Schwegel, C.A. et al. (2001). "Speciation and preservation of inorganic arsenic in drinking water sources using EDTA with IC separation and ICP-MS detection." Journal of Environmental Monitoring 3(4): pp. 371-376.

[5] Francesconi, K.A. and Kuehnelt, D. (2004). "Determination of arsenic species: A critical review of methods and applications, 2000-2003." Analyst 129(5): pp. 373-395.

[6] GomezAriza, J.L., Sanchez-Rodas, D., Beltran, R., Corns, W.T., Stockwell, P.B. (1998) Evaluation of Atomic Fluorescence Spectrometry as a Sensitive Detection Technique for Arsenic Speciation. Appl. Organomet. Chem. 12, pp 439-447.

[7] Sanchez-Rodas, D., Corns, W.T., Chen, B. and Stockwell, P.B. (2010). Critical Review Atomic Fluorescence Spectrometry: a suitable detection technique in speciation studies for arsenic, selenium, antimony and mercury J. Anal. At. Spectrom., 25, pp 933946.

[8] Gomez-Ariza, J.L., Sanchez-Rodas, D., Giraldez, I., and Morales, E. (2000). A comparison between ICP-MS and AFS detection for arsenic speciation in environmental samples.Talanta.,2000, 51 pp 257268.

SC2WG52_N_76_PNWI_ISO_WD_Arsenic_species_HPLC_HG-AFS.pdfContents PageForewordIntroduction1 Scope2 Normative references3 Terms and definitions4 Principle5 Interferences6 Apparatus6.1 General

7 Reagents and standards8 Sampling, preservation and storage of drinking, surface and ground water samples9 Procedure9.1 Instrument optimization9.2 Calibration9.3 Sample measurement

10 Expression of results11 Test reportAnnexA (informative)Example - Layout of LC-HG-AFS(informative)Example of experimental conditionsBibliography

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