lecture 01 analytical techniques
TRANSCRIPT
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ENVIRONMENTAL ANALYTICAL TECHNIQUES
ENS-801 and ENE-801
Credit Hour: 3 (1+2)
MS Environmental Science/Engineering
Semester -I (Sep 09, 2013 January 10, 2013)
Instructor: Dr. Muhammad Arshad
References
1. IESE Lab Manual
2. Standard Methods for the Examination of Water and
Wastewater20th edition, 1999
1. Fundamentals of Environmental Sampling and Analysis
John Wiley & Sons, Inc., Publication
Course Contents
1 Environmental Sampling: Sample Collection and Preservation2 Methods of Instrumental analysis
3 Determination of Alkalinity and Water Hardness
4 Determination of Elemental Composition of solid Samples using XRF/LIBS
5 Analysis of Organic Contaminants in Water by Gas Chromatography
6 Estimation of Optimum Coagulant Dose using Jar Test Apparatus
1st One Hour Test
7 Preparation of Solutions & Standardization
8 Determination of Residual Chlorine in Water
9 Determination of Total Organic Carbon (TOC) in water
10 Determination of Chemical Oxygen Demand (COD)
11 Determination of Biochemical Oxygen Demand (BOD)
2nd
One Hour Test12 Determination of Solid (TS,TDS,TSS,TVSS) in Water and Wastewater
13 Determination of Oil and Grease in Wastewater
14 Standard Coliform by MF Method
15 Determination of Nitrate-Nitrogen in Water using Spectrophotometer
16 Interpretation of Results using Statistical Tools
Final Exam
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What is Environmental Analytical Science?
A scientific discipline that develops and applies methods,
instruments and strategies to determine the nature andconcentrations of chemical constituents of the environment. It
helps in determining the concentration of harmful pollutants in
the environment
Two major subsections :
Qualitative analysis : What is present ?
determination of chemical identity of the species in the sample.
Quantitative analysis : How much present ?
determination of the amount of species or analytes
The Analytical Protocol
Environmental sample analysis involves several steps, including sample
collection, sample treatment and storage, followed by laboratory analysis
High quality of laboratory performance by
selecting appropriate and validate methods of sampling
selecting validate methods for sample preservation and preparation
selecting standard methods (validated) for analysis of samples
calibrating analytical instruments
practicing good record keeping of methods and results
ensuring the quality of data produced
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A typical analytical protocol used for
environmental analysis
Sampling
Usually only a small portion of sample is subjected to quantitativeanalysis, hence this laboratory sample must be representative ofthe parent sample
Samples may be homogeneous orheterogeneous
Homogeneous samples present no problem, a simple grabsample approach taken at random will suffice
Several samples have to be taken if parent sample isheterogeneous
Objectives
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The key questions to be asked before sampling begins include the
following:
1. Have arrangements been made to obtain samples from the site (e.g.
permission from the site owner)?
2. Is specialized sampling equipment required and available?
3. How many samples and how many replicates are required?
4. Are the samples required for qualitative or quantitative analyses?
5. What chemical or physical tests are required?
6. What analytical methods and equipment are needed?
7. What mass/volume of sample is required for the analytical techniques to be
used?
8. Is there a quality assurance protocol in place?
9. What types of container are required to store the samples and do you have
enough available?10. Do the containers require any pre-treatment/cleaning prior to use and has
this been carried out?
11. Is any sample preservation required and do you know what it is?
Distribution of inorganic
or organic contaminants
- can be random, uniform
(homogenous), patchy,
stratified (homogenous
within sub-areas) or
present as a gradient
- preliminary testing of the
site is beneficial to
establish the likely
distribution
Different distributions of inorganic and organic
contaminants: (a) random; (b) uniform (homogeneous);
(c) patchy; (d) stratified (homogeneous within sub-areas);
(e) gradient
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Environmental Sampling Approaches: Where and When
Judgmental
Selection of sampling locations based on professional judgment using prior
information on the sampling site, visual inspection and/or personalknowledge and experience
Systematic
Systematic sampling subdivides the area concern by square or triangle grids
and then collect sample from nodes or a fixed location of each grid
Stratified Random
Divides sampling population into several non overlapping strata. Each stratais more homogenous than whole population. Strata could be temporal or
spatial and sample size can be adjusted
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Sampling Techniques
Soil Sampling
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Surface Water & Wastewater Sampling
Ground Water Sampling
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Sampling AirParticulate sampling: in which particles are collected on filters
Sampling Air
Vapor/gas sampling: in which air-borne compounds are trapped on a sorbent
Air sampling: (a) a typical sorbent tube; (b) the system used to carry out measurements
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Sample Preservation & Storage
In an ideal situation, samples should be analyzed in situ without storage and
transport to the laboratory
Methods of preservation are relatively few and are generally intended to fulfillthe following criteria
to retard biological action
to retard hydrolysis of chemical compounds and complexes
to reduce volatility of constituents
to reduce adsorption effects
Preservation methods constitute the following approaches:
pH control
addition of chemicals
refrigeration
Sample container: borosilicate glass or plastic (polyethylene, polypropylene
or Teflon (PTFE))
Polyethylene (P) or glass (G), or PTFE Teflon
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MAJOR CATEGORIES OF CHEMICAL ANALYSIS
Both qualitative and quantitative analysis are divided between classical methodsinvolving primarily chemical reactions and simple measurements of mass and
volume, and instrumental methods that use instruments of varying degress of
complexity and sophistication to measure quantities of analyte
Analytical
Techniques
Chemical Methods
(Classical Method)Instrumental
Method
Spectroscopic
Method
Electrochemical
MethodChromatographic
Method
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Advantages of Instrumental Methods
High Sensitivity
Accuracy Small Sample can be analyzed
Measurements obtained are Reproducible
Fast Determination
Complex sample can be handled easily
Process can be made automatic
Limitations of Instrumental methods
High Cost
Necessary to use reference substance
Skilled Persons are required
Solutions
A solution is a homogeneous mixture composed of a solute
and a solvent. The solute is dissolved in the solvent.
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Preparation of Solutions (formulae)
1. If solute is solid
1000
(ml)solutionofVolume(g)Mol.Wt.Molarity
(g)requiredsoluteofMass
1000
(ml)solutionofVolume(g)Eq.Wt.Normality(g)requiredsoluteofMass
2. If solute is pure liquid
1000(g/ml)soluteofDensity
(ml)solutionofVolume(g)Mol.Wt.Molarity(ml)requiredsoluteofVolume
1000(g/ml)soluteofDensity
(ml)solutionofVolume(g)Eq.Wt.Normality(ml)requiredsoluteofVolume
3. If solute is an impure liquid
(g)Mol.Wt.
10Purity%(g/ml)soluteofDensitypacking)original(insoluteofMolarity
(g)Mol.Wt.
10Purity%(g/ml)soluteofDensitypacking)original(insoluteofMolarity
Dilution M1 x V1 = M2 x V2 or N1 x V1 = N2 x V2
To prepare a standard solution of Oxalic acid and with its helpstandardize approximately 0.1M NaOH solution
Solutions Preparation
1. Oxalic Acid: Prepare 250mL 0.05M Oxalic acid solution. Oxalic acid gives aprimary standard solution. Since Oxalic acid is solid; use
Weight of Solute (g) = Molarity x Mol. Wt. of Solute (g) x Volume of Solution (mL)
1000
Wt. of Oxalic acid required (g) = 0.05 x 126 x 250 = 1.58g.
1000
Dissolve 1.58g oxalic acid in some distilled water in a 250mL flask and shake. Whenwhole of the oxalic acid has dissolved, fill the flask up to the mark with distilled water
2. Sodium hydroxide: Prepare 250mL 0.1M (approx.) NaOH solution. Since NaOHis solid; use
Weight of Solute (g)= Molarity x Mol. Wt. of Solute (g) x Volume of Solution (mL)
1000
Wt. of NaOH required (g) = 0.1 x 40 x 250 = 1g
1000
Dissolve 1g NaOH in some distilled water in a 250mL flask and shake. When wholeof the NaOH has dissolved, fill the flask up to the mark with distilled water
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Procedure
Pipette out 10mL of the NaOH solution in conical flask, add one or two drops of
phenolphthalein as an indicator. This will give pink color to the alkali. Titrate it
against oxalic acid (from burette) till the pink color just changes to colorless.
(COOH)2.2H2O + 2NaOH (COONa)2 + 4H2O
n1= 1 mole n2= 2 moles
Calculations
Mean volume of oxalic acid used = V1 mL
Acid : Base
M1V1 = M2V2n1 n2
Molarity of NaOH solution: M2 = M1V1 x n2n1 V2
Prepare 250mL of 0.5M HCl solution
Hint: HCl is an impure liquid; use
Molarity of Liquid = Density (g/mL) x % Purity x 10
Mol. Wt. (g)
Molarity of HCl = 1.19g/mL x 37 x 10
36.5g/mol
Molarity of HCl = 12.0M
Dilution
M1 x V1 = M2 x V2
Volume of HCl (mL) required = 0.5M x 250mL
12.0M
Volume of HCl (mL) required = 10.4mL
Take some distilled water in a 250mL flask, add 10.4mL HCl in it and shake.
Then fill the flask up to the mark with distilled water
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EXERCISE
Prepare 250mL of 0.1M NaHCO3 solution
Hint: NaHCO3 is solid
Prepare 500mL of 0.02M KMnO4 solution
Hint: KMnO4 is solid
Prepare 250mL of 0.5M HCl solution
Hint: HCl is an impure liquid
Atomic masses (g/mol): Na: 23, K: 39, Mn: 55, Cl: 35.5, O: 16, C: 12
EXERCISE
Prepare 250mL of 0.1M NaHCO3 solution
Hint: NaHCO3 is solid; useWeight of Solute(g) = Molarity x Mol.Wt. of Solute(g)x Volume of Solution ( mL)
1000
Wt. of NaHCO3 (g) required = 0.1M x 84.0g x 250mL
1000
Wt. of NaHCO3 (g) required = 2.1g
Take 2.1g NaHCO3 in a 250mL measuring flask, add some dist illed water and dissolve the NaHCO3 in it. Then fill the flask
up to the mark with distilled water
Prepare 500mL of 0.02M KMnO4 solutionHint: KMnO4 is solid ; use
Weight of Solute (g) = Molarity x Mol.Wt. of Solute(g) x Volume of Solution( mL)
1000
Wt. of KMnO4 (g) required = 0.02M x 158g x 500mL
1000
Wt. of KMnO4 (g) required = 1.58g
Take 1.58g KMnO4in a 500mL measuring flask, add some distilled water and dissolve the KMnO4 in it. Then fill the flask up
to the mark with distilled water
Prepare 250mL of 0.5M HCl solutionHint: HCl is an impure liquid; use
Molarity of Liquid = Density(g/mL x % Purity x 10Mol.wt.(g)
Molarity of HCl = 1.19g/mLx 37 x 10
36.5g/mol
Molarity of HCl = 12.0M
Dilution:
M1 x V1 = M2 x V2Volume of HCl (mL) required = 0.5M x 250mL
12.0M
Volume of HCl (mL) required = 10.4mL
Take some distil led water in a 250mL flask, add 10.4mL HCl in it and shake. Fill t he flask up to the mark with distill ed water