lecture 01 analytical techniques

8/13/2019 Lecture 01 Analytical Techniques

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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

lecture 01 analytical techniques

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