1 Testing of Packaged Drinking Water

Chemical requirements

By: SATISH KUMAR Scientist-B

Prequation in chemical Lab 1. Do not eat, drink or smoke in the laboratory.2. Keep the lab bench clean at all the times. 3. Use Apron/Labcoats during Analysis.4. Don’t use cell phone while doing working on

any test.5. Never open the Ammonia solution on room

temperature,before open it keep it in fridge(it’s the major cause of accident in LAB.

6.Never add water in to acid while make dilution always mix acid slowly to the water .

7. Never suck any reagent by mouth ,always suck through glass pipette using suction bulb.

8. Hydrogen per-oxide always keep in the fridge.

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GLP

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PACKAGED DRINKING WATER (OTHER THAN PACKAGED NATURAL MINERAL WATER)-

SPECIFICATION-IS:14543-2004.

Requirements as per IS:14543-2004.

5.1 Microbiological Requirements.

5.2 Requirements as per Table-1, Table-2, Table-3, Table-4

Table-1 Organoleptic and Physical Parameters.

Table-2 General Parameters Concerning Substances Undesirable in Excessive Amounts.

Table-3 Parameters Concerning Toxic Substances.

Table-4 Parameters Concerning Radio-Active Residues.

5.3 Pesticide residues as per Annex-D of IS:14543-2004.

Four Hourly Tests9

1. Colour2. Odour3. Taste4. Turbidity5. pH

Tests for each control unit (Daily)10

DescriptionTotal dissolved solidsChlorideResidual free chlorineAlkalinitySulphate

Weekly Tests111) Barium

2) Copper3) Iron4) Manganese5) Nitrate6) Nitrite7) Zinc8) Aluminium9) Calcium10) Magnesium11) Anionic Surf. Act. Agents12) Sulphide

Description Daily TestIS 14543:2004 PACKAGED DRINKINGWATER AMENDMENT NO. 1 JULY 200412

Cl.5.2 Packaged drinking water shall be clear without any sediments, suspended particles and extraneous matter it is test

by Inspection Screen which is situated out-let of filling area.

Table-1 Organoleptic and Physical parameters (Clause-5.2)

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Characteristic Requirement Method 1. Colour, max

True Colour Units 2 IS:3025(Part-4)

2. Odour Agreeable IS:3025(Part-5)

3. Taste Agreeable IS:3025(Part-8)

4. Turbidity, max 2NTU IS:3025(Part-10)

5. Total Dissolved Solids 500 mg/l max IS:3025(Part-16)

6. pH 6.5-8.5 IS:3025 (Part-11)

1.Colour, True Colour Units Max 2TCU

IS 3025(Part4)- Platinum cobalt (visual comparison)

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There are two methods

1.Platinum cobalt method(Visual)

2. Spectrophotometric method-For Industrial water.

Reagents : Dissolve 1.246 g pot. Chloroplatinate + 1 Crystalline cobaltous chloride in DW containing 100 ml of Conc. HCl dilute up to 1000 ml with DW.This standard solution is equivalent solution to 500 colour unit.

Procedure : Prepare standards having colour units 1,2,5,10,15,20, 25 with distilled water to 50 ml. Compare 50 ml sample by filling a matched Nessler cylinder to 50ml by looking vertically downward through the cylinders placed on a white surface.

2. Odour IS 3025 (Part 5)

( 4 Hourly test ) Agreeable/Disagreeable15

Procedure : Half-fill a wide-mouth glass-stoppered bottle which is cleaned with odour-free distilled water.(Pass through carbon column) Insert the stopper, shake vigorously for 2 to 3 seconds and quickly observe the odour. The sample taken for observation of odour shall be at room temperature.( odour-free distilled water can be prepared by passing distilled water through a column of granulated activated carbon.)Grade the odour as agreeable/disagreeable.

3. TASTE (4 Hourly test )

Agreeable/Disagreeable IS 3025 (Part 8)

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Reagents: Taste and odour free water(Distil water pass through carbon column) and a 2000 mg/l NaCl.

Procedure :First rinse the mouth by 2 % Nacl solution and rinse by odour free distill water then Observe the taste of the water which is at 15°C (should not exceed 27°C) by keeping mouthful water sample for about 30 Seconds and report it as Agreeable/Disagreeable. With taste rating Action Tendency Scale a-j

All the apparatus and containers using in this test should be very clean. The water under testing should be safe for drinking. When sample fails in microbiological requirements taste requirement will not be tested.

4. TURBIDITYIS:3025 (Part-10) (4 Hourly test ) 17

Principle : Based on comparison of the intensity of light scattered by the sample under defined conditions with the intensity of light scattered by a standard reference suspension under the same conditions. (formazin standard)

Procedure :1) Calibrate the turbidity meter/nephelometer by using Ref. stds 2) Shake the sample gently, pour into turbidity meter tube and read turbidity from the instrument scale or from calibration curve.

5. TOTAL DISSOLVED SOLIDSIS:3025 (Part 16)

(Daily test ) Permissible limit Max 500mg/l18

Principle : The sample is filtered and filtrate evaporated in a tared dish on steam-bath. The residue after evaporation is dried to constant mass at 103 - 105°C.

Procedure : 1) Filter a portion of sample through 0.45µm filter, pipette 100ml of this sample to evaporating dish placed on steam-bath. 3) Evaporate, dry it in hot air oven at 179-181°C.C until constant weight, (usually 2hr). Calculate weight of the residue and calculate Total Dissolved Solids. Total residue, mg/l =Wt. of residue in mg*1000/vol of sample

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P H meter

Reference electrode20

6. pHIS 3025 (Part 11) 4 Hourly tests

Permissible range 6.5 - 8.521

Principle: pH is a measure of the acidity or basicity of an aqueous solution. pH = - log10[H+]

By measurement of the electromotive force of cell consisting of an glass electrode immersed in the test solution and a reference electrode. The electromotive force is measured with a pH meter.

Procedure : 1) Calibrate the pH meter by using std buffers. The std buffers should be near pH of the sample.(4-7 buffer)

2) Wash the electrode with distilled water and keep the sample, let it stabilize for few minutes and take the pH reading and note temperature.

3) Take a second reading with a fresh aliquot of sample and report average value.

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DAILY ,WEEKLY & MONTHLY SIX MONTHLY TESTS

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Table 2 General Parameters Concerning

Substances Undesirable in Excessive Amounts

SPECTROPHOTOMETER24

Principal of UV-Spectrophotometer

Principle of UV spectroscopyUV spectroscopy obeys the Beer-Lambert law,

which states that: when a beam of monochromatic light is passed through a solution of an absorbing substance, the rate of decrease of intensity of radiation with thickness of the absorbing solution is proportional to the incident radiation as well as the concentration of the solution.The expression of Beer-Lambert law is-A = log (I0/I) = EclWhere, A = absorbanceI0 = intensity of light incident upon sample cellI = intensity of light leaving sample cellC = molar concentration of soluteL = length of sample cell (cm.)E = molar absorptivity

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Work instruction for UV spectrophotomer

There may be two type of UV Spectrophoto meter viz. Double beam or single beam.

Before work on UV-Spectrophotometer On it before 15 minute before to get stabilized.

First set zero or 100 % T according to spectrophotometer model.

First standardization with Std.1,2,3,4 & 5 on OD mode or data mode.

Then finally take the product water reading and construct the graph

The std. graph should be straight line

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1.Barium as BaAnnex F of IS 13428 or IS 15302(Weekly test ) Permissible limit Max

1.0mg/l27

Procedure : 1) Acidify 1.5 lit sample with dil HCl and concentrate to 200ml.

2) Add 0.5g of ammonium chloride and ppt iron and aluminium with NH4OH. 3) Boil, filter and wash. To filtrate add excess (10ml) ammonium acetate solution, keeping total volume to 200ml.

4) Heat to boil add 5ml of ammonium bichromate solution, allow to cool and filter wash the ppt with dil ammounium acetate wash solution.

5) Dissolve the ppt in about 10ml 1:1HCl and hot water.

6) Wash the filter and dilute the solution to 400 ml and add about 50ml fresh 10% potassium iodide solution, mix, carefully titrate liberated iodine with 0.1N Sodium thiosulphate solution.(This titration to be carried out in 500 ml Idometric flask)

1ml 0.1N Sodium thiosulphate (Na2S2O3) = 4.578 mg Ba

2. Copper as CuIS 3025 (Part 42)- Neocuproine method

(Weekly test ) Permissible limit Max 0.05mg/l

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Principle : Cu(II) is reduced to Cu(I) by hydroxylamine hydrochloride and pH is adjusted to 5 by sodium citrate solution. Cu(I) forms a soluble yellow complex with neocuproine, this is extracted with chloroform & absorbance measured spectrophotometer at 457nm. A series of Std. Copper solutions is also treated with neocuproine & the absorbance is measured and a calibration graph is drawn.From the graph the unknown concn of Cu in Sample is calculated by comparing the absorbance data.This method is suitable for the range 0.05 mg/l to 5 mg/l of Cu.

Procedure :

Copper as CuContd.

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Extraction : 1) Transfer 50 ml of acidified(1 ml H2SO4+ 5 ml HNO3 ) sample to 125ml separating funnel add 5ml of hydroxylamine-hydrochloride, 10ml of sodium citrate, 10ml of neocuproine solution and shake well.

2) Add 20ml of chloroform and shake for 1min, collect chloroform layer in dry flask. Repeat extraction with another 20ml and combine the extracts and make upto 50ml. With iso-propyl alcohol Prepare a reagent blank by using 50ml double distilled water by same way as described above.

3) Measure the O.D. of the sample at 457 nm against reagent blank. Measure the conc of Cu from calibration graph.

Cu=mg of Cu*1000/vol. of sample

3. IRON AS FeIS 3025(Part 53) - 1,10 Phenanthroline

method (Weekly test ) Permissible limit Max

0.1mg/l 30

1,10 Phenanthroline Method:

Principle : Iron in the solution is reduced to the ferrous state by boiling with HCl and hydroxylamine hydrochloride and treated with 1,10 phenanthroline at pH to 3.3. Three molecules of phenanthroline chelate each atom of ferrous iron to form an orange-red complex. Range 75 to 500µg/l of iron.

Procedure : 1) 100ml of sample add 1ml of NH2OH.HCl solution and 2ml conc. HCl and boil the solution until the volume is reduced to 20ml. 2) Cool to room temp. add 10ml of ammonium acetate buffer solution first and add 10ml of 1,10 phenanthroline solution. 3) Dilute to 100ml with water and mix, allow to stand for 10 to 15 min. and measure the O.D at 510nm against reagent blank.

4) Prepare a calibration curve with 10 to 100µg(0.1mg) of Fe as per above procedure and calculate the Iron concn. from the calibration curve.

4. Manganese (as Mn) IS 3025 (Part 59):2006

PERIODATE CALORIMETRIC METHOD (Weekly test ) Permissible limit Max

0.1mg/l 31

Principle : The Mn in the sample is oxidized with potassium periodate, the pink colour obtained is matched with standards.

Proceedure : 1) To 100ml of sample in 250 ml conical flask, add 4ml of dil H2SO4 and evaporate, add few drops of hydrogen peroxide-nitric acid mixture until organic matter completely destroyed.

2) Cool, add 25 ml of distilled water 2ml of phophoric acid, 0.2g of potassium periodate, bring to boil and keep for 1hr.

3) Cool and transfer to Nessler tube adjust the volume to 50ml with distilled water and mix well.

4) Prepare Mn standards 0.02 , 0.04,0.06,0.08 and0.1 mg concentrations and develop colour as above and match with standard.

4. Manganese (as Mn) IS 3025 (Part 59):2006

PERIODATE CALORIMETRIC METHOD (Weekly test ) Permissible limit Max 0.1mg/l

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5. Nitrate as NO3IS 3025 (Part 34) (Weekly test ) Permissible limit

Max 45mg/l Chromotropic acid method.33

Principle : Two moles of nitrate nitrogen react with one mole of chromotropic acid to form a yellow reaction product having max absorbance at 410nm.

Procedure : 1) Take 2.0ml of filtered sample into dry 10ml volumetric flask.

2) To each flask, add 1drop of sulphite-urea reagent and place the flasks in cold water tray (10 to 20°C) and add 2ml of antimony reagent and mix.

3) After 4min add 1ml of chromotropic acid reagent, mix and let stand for 3 min.

4) Add conc. H2SO4 to bring volume near the 10ml mark and mix well.

5) Read absorbance at 410nm after 15min.

6) Prepare calibration curve ranging 0,1,5,10,25,40 to 50 mg/l conc as per above procedure.

7) Calculate the conc of NO3 in the sample by using calibration curve.

5. Nitrate as NO3IS 3025 (Part-34) (Weekly test ) Permissible limit

Max 45mg/l Devardas Alloy method.34

5. Nitrate as NO3IS 3025 (Part-34) (Weekly test ) Permissible limit Max

45mg/l Devardas Alloy method.

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The nitrate and nitrite is reduced to ammonia under hot alkaline conditions in the presence of the reducing agent ( Devarda's alloy). The ammonia formed distils and is trapped in a receiving flask containing boric acid. The ammonia can be determined either by direct nesslerization or acidimetrical1y. This method is recommended for nitrate nitrogen and nitrite nitrogen. Ammoniacal nitrogen ( NH3-N ), mg/l =(A-B)*280/vol.

6. Nitrite as NO2IS 3025 (Part 34) ---Weekly testPermissible limit Max 0.02mg/l 36

Principle : Nitrite forms reddish purple azo dye at pH 2.0 to 2.5 sulphanilamide and N-(1 naphthyl)-ethylene diamine dihydrochloride (NED dihydrochloride)

Procedure :1) 50 ml clear sample in Nessler cylinder + add 1 ml of sulphanilamide solution, mix and let stand for 2 to 8 min.

2) Add 1.0ml of NED dihydrochloride solution and mix immediately and let stand for 10 min.

3) Measure absorbance at 543nm.

4) Prepare nitrite (Sod.Nitrite) standards 0.01mg, 0.02mg.0.03mg,0.04 & 0.05 mg concs and develop colour as above and prepare calibration graph .compare the absorbance of sample with calibration graph and calculate the sample concn.

How to make std solution

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1.233 g→1 litre(250 ppm)→50 ml→250 ml (50 ppm) →10 ml →1000 ml (0.5 ppm)

0.5 x 1 (take)/50(make up volume)=0.010.5 x 2 (take)/50(make up volume)=0.020.5 x 3 (take)/50(make up volume)=0.030.5 x 4 (take)/50(make up volume)=0.040.5 x 5 (take)/50(make up volume)=0.05

7. Zinc as ZnIS 3025 (Part49) ---Weekly testPermissible limit Max 5 mg/l 38

Principle : Zn(II) forms a soluble blue complex with 2-carboxy-2-hydroxy-5sulfoform-azyl benzene (zincon) at pH 9.0. The coloured complex obeys Beers law. and is suitable for spectrophotometric measurements.

Proceedure : 1) To 50ml of sample add 1ml of Conc HCl and boil for 5 min. 2) Cool and adjust the pH to 7 with NaOH. And make upto 50ml. 3) Take 10ml of this solution in a flask add 0.5g of Sodium ascorbate, 1ml of cyanide solution 5ml of buffer solution 3ml of Zincon solution and 1ml of cyclohexanone solution in the same order. 4) Make up to 500ml with distilled water and measure O.D. at 620nm. 5) Treat 50 ml portions of standard solutions containing 0·02, 0·05, 0·1,0.5,1.0 & 5.0 mg/l of zinc and treat as above and measure the absorbance. Plot absorbance versus milligram of zinc for the standards to get a calibration graph. Read the concentration of zinc in the sample from the calibration graph.Prepare calibration curve and calculate Zn conc in the sample.

8. Aluminium as AlIS 3025 (Part 55) or IS:15302 --Weekly

testPermissible limit Max 0.03 mg/l 39

Principle : Aluminium forms a red to pink complex with Eriochrome cyanine R at pH 6.0 and this coloured complex obeys Beers law. The range of operation is 20 to 300 µg/l as Al.

Interferences : Metals like Iron and Manganese interference can be eliminated by adding ascorbic acid. Fluoride interference can be overcome by adding known amounts fluoride to the standards and compare with this calibration curve. Phosphates interference can be eliminated during sample treatment. Alkalinity interference can be removed by acidifying samples just beyond neutralization point of methyl orange.

Procedure : 1) Place 25ml of sample in a conical flask, add few drops of methyl orange indicator, titrate with0.02N H2SO4 to a faint pink colour. Record this titre volume (V). 2) Take two similar samples in 50ml volumetric flasks add V and 1ml excess of 0.02N H2SO4. To one sample add 1ml of EDTA solution. This is reagent blank. 3) To both samples add 1ml of ascorbic acid, 10ml of buffer solution, 5ml of working dye solution.

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Aluminium as AlContd.

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4) Dilute with water up to the mark, set the instrument to zero absorbance at 535 nm by using reagent blank. Take sample absorbance also and calculate aluminium concentration from the calibration curve.

9. Chloride as ClIS 3025 (Part 32)-Argentometric Method

Permissible limit Max 200 mg/l 42

Principle : In a neutral or slightly alkaline solution, potassium chromate can indicate the end point of the silver nitrate titration of chloride. Silver chloride is precipitated before red silver chromate is formed.

Procedure : 1) To 100ml of sample at pH range 7 to 10 add 1.0ml of potassium chromate indicator solution and titrate with standard silver nitrate solution to a pinkish yellow end point. 2) If sulphide, suiphite or thiosulphate is present add 1ml of hydrogen peroxide and stir for 1min and directly titrate as per 1st step.

Chloride = Vol of AgNO3 *N of AgNO3 *35.450

Vol of PDW

10. Sulphate as SO4IS 3025 (Part 24)-Turbidity method

Weekly test --Permissible limit --Max 200 mg/l 43

Principle : Sulphate ion is precipitated in hydrochloric acid medium with conditioning reagent (barium chloride + gelatin) to form barium sulphate crystals of uniform size. By using nephlometer (Turbidity meter) sample concentration of sulphate ions can be determined by using standard calibration curve.This method is applicable in the range of 1 to 40mg/l of SO4.Procedure : 1) Take 20ml of filtered (0.45µm filter) in conical flask, add 1ml of HCl solution, 1ml of conditioning reagent and mix for 1min. 2) Read the turbidity by using turbidity meter/ spectrophotometer. 3) Prepare a series of standards taking at least 4 standards and run a blank and follow the above steps. Prepare a calibration curve of standards mg/l vs absorbance.4.9 Calculation-Read the sulphate concentration of sample directly from the calibration curve..

11. Alkalinity as HCO3IS 3025 (Part 23)-Indicator Titration method

Daily Test Permissible limit Max 200 mg/l 44

Principle : Alkalinity of water is the quantitative capacity of an aqueous medium to react with hydrogen ions to pH 8.3 (Phenolphthalein alkalinity) and then to pH 4.5 (total alkalinity or methyl orange alkalinity).

Procedure : 1)Pipette 50ml or a aliquot of sample into 100ml conical flask. If the pH of sample is over 8.3 add 2 or 3 drops of phenolphthalein indicator and titrate with standard sulphuric acid solution till the pink colour disappears. Reading is A ml. 2) Add 2 to 3 drops of mixed indicator (MR+BCG)to the same flask and titrate with standard Sulphuric acid to light pink colour. Record the volume of standard acid used for this titration say B ml.

Calculate the Total Alkalinity by using formula and by using V1+V2 ml as titre volume. (A +B) x N x 50000/vol. sample

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12. Calcium as CaIS 3025 (Part 40)-EDTA Titration

method Permissible limit Max 75 mg/l ----

Weekly test 46

Principle : Calcium can be determined directly with EDTA at pH 12 to 13 in a sample containing both Ca and Mg. Mg is largely precipitated as the hydroxide and an indicator is used which combines only with calcium.Procedure : 1) Take 50ml or suitable volume of sample in a conical flask add 2 ml of NaOH solution to raise pH 12 to 13 and stir. Add 1g of Patton and Reeders indicator. 2) Titrate immediately with standard EDTA solution with continuous stirring from wine r ed to the proper end point blue colour. 3) Check the end point by adding 1 or 2 drops of titrant in excess to make certain the correct end point. 4) Calculate the calcium by using formula. Calcium (Ca), mg/l == vol. of EDTA*Ca eq of EDTA *1000 Vol. of PDW

12. Calcium as CaIS 3025 (Part 40)-EDTA Titration method

Permissible limit Max 75 mg/l ---- Weekly test 47

13. Magnesium as MgIS:3025 (Part-46)-EDTA Titration method Permissible limit Max 30 mg/l –weekly test48

Principle : Water sample containing both Ca and Mg is titrated with EDTA at pH 10, by using EBT indicator, which estimates Ca and Mg. In a separate titration against EDTA at pH 12 to 13 range using P&R indicator calcium is estimated. From these values Mg content may be calculated.

Procedure : 1) Take 50ml or suitable volume (V) of sample in a conical flask, add sufficient quantity of buffer solution to bring pH to 10, add 3 to 4 drops of EBT indicator solution and titrate with 0.01M EDTA solution till the red colour changes to pure blue end point free from violet tinge. Volume of 0.01M EDTA consumed is V1ml. 2) In a separate conical flask take same quantity of sample (V) used in step 1, add 2 ml of NaOH solution, add P&R indicator and titrate with 0.01M EDTA solution till end point clear blue colour. Volume of 0.01M EDTA consumed is V2 ml. 3) (V2-V1) ml is the volume of EDTA consumed for Mg, by using this volume Mg concentration can be calculated by this formula Mg= 0.2435 X 1000 X(V2-V1)

vol of PDW

14. Residual free chlorine IS 3025 (Part 26) Ortho-toluidine method

Permissible limit Max 0.2 mg/l -- Daily Test 49

Principle : The stability of oxidized ortho-toluidine decreases as pH increases. Sodium di (2-ethyl-hexyl) sulphosuccinate stabilize the colour by free chlorine and ortho-toluidine at pH 7.0. The final solution should have pH between 6.5 to 7.5.

Procedure : 1) 100ml of sample + 5 ml buffer + 3 drops ortho toludine → magnetic stirrer (blue colour), if yellow colour discard it and repeat it.

Blank -100 ml DW + 5 ml buffer + 3 drops ortho toludine → magnetic stirrer 2.Construct a calibration curve by making dilutions with chlorine demand free distilled water of standardized hypochlorite solution. 3) Measure the absorbance of sample and standard solutions at 625 nm and calculate the free residual chlorine from the calibration curve.(A )

RFC - Std. solution preparation:50

Sod. Hypochlorite 4 % →1 ml →200 ml →120 ppm

req ppm x req vol ---------------------- = no of mls for req vol          stock 

e.g. Make up 50 mls vol of 25 ppm from 100 ppm 

25 x 50 / 100 = 12.5 mls. i.e. 12.5 mls of 100 ppm in 50 ml volume will give a 25 ppm solution 

Values of RFC51

std absorbancepdw 0.05std 1 0.1std2 0.2std3 0.3std4 0.4std5 0.5

RFC Graph52

Gas stripping apparatus53

15. Anionic surface active agents (as MBAS)Annex K of IS:13428 Permissible limit Max

0.2 mg/l -- Daily Test 54

Principle : Formation of salts from methylene blue and anionic surfactants in an alkaline medium. Extraction of these salts with chloroform and acid treatment of the chloroform solution. Elimination of any interference by extraction of anionic surfactant-methylene blue complex from alkaline solutions and shaking with acidic methylene blue solution. Measurement of the absorbance of the separated organic phase at 650 nm. Dodecyl benzene sulphonic acid Na salt is used for prepn. Seies of std. solns

Procedure : 1) Place 1lit of sample in the gas-stripping apparatus, add 100g of NaCl, add 100ml of ethyl acetate and pass air or nitrogen through it for 5 mins.(20-50 LPH Pressure) Transfer the organic phase into a separating funnel and any water in the separating funnel return to gas-stripping apparatus. 2) Repeat the stripping with 100ml of ethyl acetate and collect all the organic phase portions by filtering through dry filter paper into a 250ml flask. Rinse the filter paper and funnel with 25ml of ethyl acetate. 3) Remove all the ethyl acetate by evaporation on the water bath. 4) Dissolve the residue in 5ml of methanol and 50ml of water and transfer to 100ml volumetric flask and dilute to the mark with water.

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15. Anionic surface active agents (as MBAS)Annex K of IS:13428

contd.56

5) Carryout a blank test as per above procedure. 6) Transfer a measured volume of the above sample into separating funnel add 5ml of neutral methylene blue solution, 10ml of buffer solution and 15ml of chloroform and shake uniformly for 1min . Filter the chloroform layer through a chloroform wetted cotton or glasswool filter into a 50ml volumetric flask. 7) Dilute to the mark with chloroform, mix and measure the absorbance at 650nm and calculate the concentration of MBAS from the calibration graph.

16. Sulphide as H2SIS 3025 (Part 29)-Methylene Blue Method

Permissible limit Max 0.05mg/l ---weekly test57

Principle : This method based on the reaction of sulphide, ferric chloride and dimethyl-p-phenylenediamine to produce methylene blue. Ammonium phosphate is added after colour development to remove ferric chloride colour.

Procedure : 1) Take two test tubes A and B add 7.5ml of sample to each test tube. 2) Add 0.5ml of amine-sulphuric acid reagent, 0.15ml of ferric chloride solution to Tube-A and mix. 3) Add 0.5ml of 1:1sulphuric acid and 0.15ml of ferric chloride solution to Tube-B and mix. The presence of sulphide will be indicated by the appearance of blue colour in tube-A. 4) Wait for 3 to 5 mins and add 1.6ml of diammonium hydrogen phosphate solution to each tube, wait for 3 to 15 mins and take absorbance and calculate the concentration of sulphide from the calibration curve.prepare calibration curves on thebasis of calometric tests made on Sodium suphide solns (analsedby titration method ).plotting concn as absorbance.Read sulphide concn. from the calibration curve.

Toxic Elements

Mercury (Cold vapour) by Atomic Absorption Spectrophotometer.

CadmiumArsenicCyanideLeadChromiumNickel

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Atomic absorption spectroscopy59

Principal of AAS

Atomic absorption spectroscopyare used to determine the concentration of anelement in solution. The ground state atom absorbs light of the samecharacteristic wavelengths as it emits when

returning from the excited state to the ground state.

The intensity of the absorbed light is proportional to the concentration of the element in the flame.

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Pesticide Residue61

Gas chromatography mass spectrometry (GC/MS) is an instrumental technique, comprising a gas chromatograph (GC) coupled to a mass spectrometer (MS), by which complex mixtures of chemicals may be separated, identfied and quantified.

Two Instruments are used to testing of pesticide residue.

1. GC-MS2. HPLC

GC-MS62

High Partition Liquid Chromomatography

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Principal of HPLC

Chromatography is a technique by which a mixture sample is separated into components. HPLC is an analysis method that yields high performance and high speed compared with traditional column chromatography because of the forcibly pumped mobile phase.

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1. DDT 2 Lindane mg3 BHC mg 4 Endosulfan 5 Monocrotophos 6 Ethion 7 Chlorpyrifos 8 Phorate 9 2, 4-D10 Butachlor

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11 Isoproturon 12 Alachlor 13 Atrazine 14 Methyl Parathion 15 Malathion mg16 Aldrin & dieldrin mg 17 Total Pesticide Residues mg18 Polychlorinated biphenyl (PCB) 19 Polyaromatichydrocarbon (PAH)

FTIR

FTIR offers quantitative and qualitative analysis for organic and inorganic samples. Fourier Transform Infrared Spectroscopy (FTIR) identifies chemical bonds in a molecule by producing an infrared absorption spectrum. The spectra produce a profile of the sample, a distinctive molecular fingerprint that can be used to screen and scan samples for many different components. FTIR is an effective analytical instrument for detecting functional groups and characterizing covalent bonding information. It’s used in mineral oil testing.

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FTIR68

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