Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

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“Step Out From the Old to the New”

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“The Right to Information, The Right to Live”

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“Invent a New India Using Knowledge”

है”ह”ह

IS 5055 (1996): Lecithin, Food Grade [FAD 8: FoodAdditives]

IS 5055 : 1996

Indian Standard

LECITHIN, FOOD GRADE - SPECIFICATION( First Revision)

ICS 6722020

e BIS 1996

BUREAU OF INDIAN STANDARDSMANAK BHA VAN, 9 BAHADUR SHAH ZAF AR MARG

NEW DELHI 110002

September 1996 Price Group 4

AMENDMENT NO. I FEBRUARY 2006TO

IS 5055 : 1996 LECITHIN, FOOD GRADE-­SPECIFICAnON

( First Revision)

I Page I. Table I, S'/ No (viu), coI3]- Substitute '10' [or '100'

(FADlI)

Reprography Unit, BIS, New Deihl, Indra

Food Additives Sectional Committee, FAD 8

FOREWORD

This Indian Standard ( First Revrsion ) was adopted by the Bureau of Indian Standards, after the draft finahzedby the Food Additives Sectional Committee had been approved by the Food and Agnculture DIVISIon Council

With the Increased production of processed foods, manufacturers have started adding a large number of sub­stances, generally In small quantities, to Improve the appearance, flavour, texture or storage properties of theprocessed foods As certain impunues In these substances could be harmful, It IS necessary to have a strictquahty control of these food additrves A senes of standards was, therefore, prepared by this Institution to coverpunty and rdennfication of these substances These standards would help In checking purity, which requires tobe checked at the stage of manufacture, for It IS extremely difficult (and In many cases impossible) to detect theIgtpunty once these substances have been added to the processed foods Besides, these standards are Intended toguide the indigenous manufacturers In making their product conform to specificanons that are accepted bySCientists, health authonnes and international bodies, and the consumer mdustnes to use them Within the quan­tity permitted by the health authonties

Lecithin, WIdely used as ann-oxidant and emulsifler, IS permitted under the Prevention of Food AdulterationRules, 1955, as well as the Fruu Product Order, 1955

This standard was first ISSUed In 1969 It IS being revised to make the followmg changes/additions

a) To upgrade the standard by increasing the punty limitb) To provide a separate clause for descnpuon including the solubrhty property to keep It mime with

food chemical codex NRCc) To Incorporate the amendment No I Issued to earher versiond) To include the requirements for heavy metals and peroxide value, and their methods of teste) To provide mformation as to whether It IS of arurnal ongm or vegetable ongm or both and the

expiry date under marking clause

Cbemical Names and Formulae

The recogmzed chemical names are lecnhm. phospholutem, phosphandes, and phosphohpids Food grade leer­thm IS a complex mixture of acetone Insoluble phosphatides consistmg chiefly of phosphaudly choline, phos­phaudyl ethanolamme, phosphatidic acid, and phosphatidyl mosrtol combined With various amounts of othersubstances, such as tnglvcendes, fatty acid and carbohydrates Formulae for vanous phosphatrdes are givenbelow

CH20COR

ICHOCOR

I o~CH2~C~CH2 N ICH]I]

lPHOSPHAl'IDYl CHOLINE

(LECITHIN FRACTION)

PHOSPHATIDIC ACID

CH20COR,CHOCOR

1\CH20POCH2CH2 NH2

/OH

PHOSPHATIDYl ETHANOLAMINE

(CEPHALIN FRACTION)

CH20COR

IC

1

HOCOR HO OH

o~ 0CH2- jP-O

OH HO OH

PHOSPHATIDYL INOSITOL

R =vanous saturated and unsaturated fatty acids groups( Continued on third cover page )

( Connnued from second cover page)

In the preparatIon of dus standard considerable amount of assistance has been denved from the Food ChemicalCodex, Thud Bdmon, National Academy of SCiences, National Research Council, Washmgton DC, USA

For the purpose of deciding whether a particular requirement of this standard IS complied with the final valueobserved or calculated, expressmg the result of a test or analysis, shall be rounded off In accordance with IS 2 1960'Rules for rounding off numencal values ( revised)' The number of sigmflcant places retained In the rounded offvalue should be the same as that of the specified value III this standard

IS 5055 : 1996

Indian Standard

LECITHIN, FOOD GRADE -- SPECIFICATION

( First Revision)

3 DESCRIPTION

4,1 Identifieatiod

1 SCOPE

4 REQUIREMENTS 15

15

F

(i

c

03

10

40

35

Annex uJ Clauve ut

thl< IS 1699Standard 1995

(3) (4) (5)

62" 13

Require- Methud of Test, Ref toment

Characterasbc

(t) (2)

r) Purity, as acetone-

Insoluble residue,percent by mass, Min

II) Morsture, percent hvrna...... Max

III) Benzene insolublematter, percent bymass. Max

tv) Acrd value, Max

v) Ar~n1c ( "-_ As ),mglkg.Max

VI) Lead (a, Pb), mg/kg,Max

VII) Heavy metals .., (Pb)mglkg,Max

51No

VIII) Peroxide value Max 100 II

"Eqervalents to 2 2 percent of phovphornus when determined, by the method given In Annex J)

sodium III a soft glass tube, and heat to redness Plungewhile hot into about 10 mI of disnlled water, heat toboihng and filter Add a few crystals offerrous sulphateto the filtrate, bod and add dilute sulphunc acid untilJust aCIdIC Allow to stand for 15 mmutes, filter andwash A blue precipitate shall be formed

4.1.3 Reflux I g of'lecitlun for I hour WIth 25 011 of0 5 Nethanohc potassium hydroxide When cooled to O'C .i

precrprtatc of potassium soap shall be obtained

4.2 Gossypol Te~t

The total gossypol content III cottonseed lccitlun shall1I0texceed 'i percent by mass The method for detemu­nauon of gossypol IS given III Annex A

4.3 The material shall also conform to the reqiurementsgiveu m Table I

Table 1 Requirements for Lecithin, Food Grade

5 PACKING AND MARKING

5.1 Packing

The matenal shall be securely packed in well-filledcontainers WIth nummum access to hght and arr The

71tleIS No

3,2 The matenal is insoluble In water but charctensncallyhydrated WIth swellmg It IS Insoluble III acetone but50luble In chloroform and benzene The 'Iccithm frac­tion' ISsoluble while ccplialin fraction ISinsoluble inethanol

NO I J- [he solubslrty I'" mtended only av mformauonregarding approximate ..olubihty and 1\ not to beconsidered a" a quality requuement and IS 01 mmor srgrufi­cance 8!1. a means of tdenuf....atron (If detcmunanon ofpuntv and dependence must he placed on other ..pecrtica­lion"

4.1.2 Blue Prectpttate with Ferrous Sulphate

Fuse about 0 5 g of the material WIth about 0 05 g of

4.1.1 Yellow Precipitate WIthAmmOnium Molybdate

Igmte I g ofthe matenal With 2 g of anhydrous sodiumcarbonate Cool and dissolve the residue In 5 ml ofwater and 5 ml of nunc acid Add 5 ml ofammoruurnmolybdate and heat to boiling A yellow prccpnateshall be formed

5106 1996 Sodiurn carboxymethyl cellulose, foodgrade ( second revtsum s

3, I The matenal is a VISCOUSsemr-hquid With a charac­tcrtstic odour It IS light yellow to brown dependingupon whether It ISbleached or unbleached Lectthm ISobtained from egg or edible vegetable oilseeds bySUItable dehydration or solvent extraction usmg foodgrade solvents It may also be obtained from arumalsources Fdible drlucnts, such as cocoa buller andvegetable OIlsmay be added to Improve functional andflavour charactensucs

1070 1992 Reagent grade water t tlurdrevrston v

1699 1995 Methods of sampltng and test forsyntheuc food colours ( vecond re~r"on)

This standard prescnbes the requirements and themethods ofsamphng and tests for lecnhm, food grade

2 REFERENCFS

IS 5055: 1996

containers shall be such as to preclude contaminationof the contents WIth metals or other rmpunnes

5.2 Markin~

Each container shall be legibly and indelibly markedWIththe following mfonnauon

a) Name ofthe matenal mcludingthe words 'FoodGrade'

b) Name and address ofthe manufacturer,

c) Mrmmum net content,

d) Batch or code number,

c) Whether made from vcgctable ongm or animalongm or both,

l) ExpIrydate, and

g) Any other requircrncnts as specified under theStandards of WelKhl' and Meavuresi Packuged Commodrue-q Ruin, 1977/l'reven­II'm oj Food Adulterauon Ruin, 1955

5.2. tHIS ( erufic alum Marking

The product may also be marked with the StandardMalk

5.2.1.1 The use of the Standard Mark IS governed bythe provrsions of the Bureau ofIndian Standard, Act,1986 and the Rules and Regulations made thereunderThe details of condiuons under whtch the licence forthe usc of the Standard Mark may be granted 10

manufacturers or producers may be obtained from IheBureau of Indian Standards

6 SAMPLING

Representative samples of the matenal shall be drawnaccordrug to the mel hod prcscnbed 111 4 of IS 1699I')')'i

7 QUALrrv OF REAGENTS

Unlcss specified otherwise, pure chemicals and distilledwater (lee IS 1070 1992) shall be cmployed In tests

NO II Pure chemu.al-, vhall mean chermcals that dunot cuntatn tmpuntrc-, which Kneel the experimental

TL"UIt...

ANNEX A( ( 'Iausc 4 2 )

DETERMINATION OF TOTAL GOSSYPOL

A-I PRINCIPLE

The term 'total gossypol' designates 'free gossvpol'bound gOSSYPOl' and closely related pigments whichafter hvdrclvsi and reaction wrth an orgamc anunc(p-ll!llSldme or amhnc ) give a product idenncal spec­lrophotomctncally WIth that obtamed from pure gossy­pol and the sallie reagenr In this method, total gossv­pol is completely removed from lccuhm m a 10-mmutecxtracuon dunng which gossypol IScomplexed With ncu­trnhzcd I-olll1lno-l-propanol m dunethvl fonnanudc Thedifference III absorption of aliquot portions of theextract before and after reaction With amlmc SCIVCS as ameasure of the total gossvpol content. and allows propercorrection for the background absorption of the extracts

A-2 APPARATlJS

A-2.1 Photoelectric Colorimeter - With a filterhavmg a maxunum transmutance m the VICllllty of 440nm or ,I spectrophotometer rsolanng a band at 440 nm

A-2.2 Pillette~, Volumetric ~ 1,2,4,6, I! and III 1111

A-2.J Flasks, Volumetric - 25.50, and J()() ml

A-2.4 Insulated Wah:r Bath

I'hcnnostancallv controlled 10 ± l°e. and eapable of

keeping the water at a gentle bot! The water-bath shouldbe equipped WIth clamps 10 securely hold the volumet­nc flasks IlIIlIIer'iC<! 111water

A-3 REAGENTS

A-3.1 j"oPropyl Alcohol-Hexane Mixture

MIX(,0 volumes 01 reagent grade I\opropyl alcohol and40 volumes of commercial hexane

A-J.2 Cllmplexin~Reagent

Pipette 2 Ill] of1-arruno-l-propanol and 10 ml ofglacialaceuc acid mto a 100-ntl volumetric flask, cool to roomtemperature, and dilute to volume with dimethylfonnanudc ( N-N dimethyl formarrude, redistilledbetween] 'i2°to 151°C) TIllS reagent IS stable for oneweek after preparation

NOTE~ ,-ammu-i-prupanol may be redrstrlled if colouredIts boiling stam. I" 1RR"C, and It may be convenientlydistilled under water pump vacuum

A-3.3 Anilinc

Reagent grade, redrsnlled over LInC dust Store III arefrigerator and redrstil when the absorbance of thereagent blank exceeds 0 022

A4 STANDARD GOSSYPOL SOLUTIONS2

A-4 STANDARD GOSSYPOL SOLUTIONS

A-4.t Weigh accurately 25 rng of pure gossypol or27 9 mg of pure gossypol acetate, dissolve m and makeup to 50 ml volume WIth the complexmg reagent Ifexactly 25 mg of pure gossypol IS used, the solutionshall contarn 0 5 mg/ml

A-4.2 Calibration Curve

Pipette 2, 4,6, 8 and 10 mIof standard gossypol solutioninto 50-m1volumetric flasks

A-4.J To each standard add sufficient complexmgreagent 10make up the total volume to 101111 Use 10 mlof the complexmg reagent as a blank

A-4.4 Heat the flask contanung the standards and theblank m a boihng water bath (100" C) for 30 nunutcs,cool and dilute to volume With the I vopropyl alcohol­hexanenuxture

A-4.5 PIpette in duplicate 2 1111 ahquots of each dilutedstandard and of the blank mto 25-ml voluiuetnc flaksDIlute one set of ahquots to volume With the Isopropylalcohol-hexane mixture and reserve as reference\DIU/IOn,

A-4.6 To the other set ofahquots, add 2 ml of atuhne.heat in aborhng water-bath for 30 mmutes,cool to roomtemperature and dilute to volume With Isopropylalcohol-hexane mixture Allow the llask to stand at roomtemperature for one hour after drlunon and nuvmg

A-4.7 With a spectrophotometer, deternunc theabsorbance of the reagent blank at 440 nm usmg thedilute blank aliquot Without am line as a reference solu­tion

IS 5055 : 19%

shall probably vary With each concentration ofgossypol m which case a cahbranon curve should beplotted and used

A-5 SAMPLE PREPARATION

Heat the sample to approximately 50"C, nux well andfilter Store at O'C, If analysis ISnot done rmmcdratelvThe analytical sample should contam from I to 5 mg ofgossypol For maximum precision. the aliquot usedshould contain 0 I mg of gossypol

A.() PROCEDURE

A-6.t Weigh sufficient quanutv of the sample matenaJas directed 111 A-5.1 into a 50-1ll1 volumetnc flask AddIIIml of the complexmg reagent

A-6.2 Use to ml of the cornplexmg reagent as thereagent blank

A-6.J Heat both the sample and the blank III a borlmgwater-bath for 30 minutes, cool to room temperature,dilute to volume with Isopropyl alcohol hexane mixtureand mix Filter through Whatman No, I or equrvalemfilter paper and collect the filtrate 111 a small glass stop­pered flask

A-6.4 PIpette duphcate ahquots (see A-5.1) of thefiltered extract and of the reagent blank into 25-mJvolumetric flasks

A-6.5 Dilute one of the ahquots to volume With theIsopropyl alcohol hexane mixture and reserve as refer­ence solutions

A-6.6 To the other aliquot, add 2 ml of'amlmc, developthe colour and determine the corrected absorbance oil440 lUll a" outlined in A-4. 7 and A-4.8.

A-7 CALCULATION

Dctcrnune the gossypol (111 milhgrams) In the samplealiquot by means of the calibration curve on thecalibration factor

A-4.S Deterrmne the absorbance of each gossypolstandard reacted with amline, usmg the appropriatediluted stand..rd as a reference soluuon Subtract theabsorbance of the reagent blank from that of eachstandard to obtam the corrected absorbance

A-4.9 Calculate the cahbratron factor by dividmg thenumber of'rmlhgrams of gossypol in the 2 OIlaliquot ofeach standard by the appropnate corrected absorbanceAverage the factors for all the gossvpol standardsWhen a photo-elccmc colonmeter IS used, the factors

3

Total gossypol,percent bymass

5 x mg gossypolm sample aliquot

Mass of sample in g x Volume ofahquot usedfor analysis

IS 5055 : 1996

ANNEXB[ Table 1, Sl No (I)]

DETERMINATION OF PURl1Y

B-t REAGENTS

B-I.l Purification of Phosphatide!

Dissolve ~ g of phosphaudes from previous acetoneinsoluble maucr deternunanon in 10 ml of petroleumether and add 25 ml of acetone 10 the soluuon Transferapproxnnatcly equal portions ofthc precipitate to eachof two 40-ml centnfuge tubes using addtUonai portions01 acetone to facrlrtate the transfer SUr thoroughly,dllulcl040 ml wnh acetone sur agam.cfull for I~ nurunau tee-bath stir agam, and then ccntnfuge for 5 nunDecant the acetone crush the solids With a stimng rod,rcfill the tube WIth acetone, stir, chill, centrifuge. anddecant ,IS before The solids after the second centnfu­gallon require no further punficauon and may be usedfor prepanng the phosphatide acetone solution Fivegrams of the punfied phosphaudes are required tosaturate about 16 lures of acetone

B-I.2 Phosphande Acetone Solution

Add a quanntv of punficd phosphaudes to sufficientacetone previously cooled to a temperature of about'Ie to form a saturated solution. and mamtam themixture at this temperature for 2 hours, shakmg rt\ igorously at IS mmutcs intervals Decant the soluuonthrough ,I rapid filter paper avoidmg the transfer ofanyundissolved solids to the paper and conducting thefiltr.uron undcr rctngcr.ued condiuons (nol above ~'C)

8-2 PROCEDURE

,",oUln,1 portion ofthe matcnal bv warnung II III a waterb.nh at ,I temperature not cvcccdmg 60 C and thennuxing 1\ thoroughlv Transfer 2 g ofa well-mixedsampleaccurately weighed IIIto a 40-m! centrifuge tubepreviously tared With a glass snrnng rod Add IS 011 ofphosphatide acetone soluuon from a burette Warm the

nuxmre rn a water bath until thelecithm melts, bul avotdevaporation of the acetone SUr unul the sample IScompletely dismtegrated and dispersed, and thentransfer the tube mto an Ice bath, dull for S rmnutes,remove from the Ice bath, and addabout one half of therequired volume of phosphatide acetone solution, pre­viously chilled for S minutes In an ICe bath Stir themixture to complete dispersion of the sample, dilute to40 ml with chilled phosphatide acetone solution (S"C),agam stir and return the tube and contents to the Icebath for 15 minutes Attheendofthe 15 mmutes chill­109 penod sur agam wlule stili m the Ice bath, removethe snrnng rod, temporarily supporting It III a verticalUPSide down posmon,and centrifuge the mixtureImme­diately at about 2 000 rev/nunfor 5 minutes Decant thesupernatant liqUid from the centrifuge tube, crush thecentnfuged solids With the same snrrmg rod previouslyused, and refill the tube to the 40-ml mark With chilled(S"C) phosphatide acetone solunon, and repeat the chill­mg, snrnng, centnfugation, and decantation procedurepreviously followed After the second cenmfugauonand decantation ofthe supernatant acetone, agam crushthe solids With the assigned surnng rod, and place thetube and ItS contents m a honzontal positron at roomtemperature unul the excess acetone has evaporatedMIX the residue agam dry the ceutnfuge tube and ItScontents at lOi"C for 4~ nun III a forced draft oven, cooland weigh

B-3 CALCULATION

Acetone msoluble residuepercent by mass (100 R!,~) B

where

R = mass ofthe residue,S= mass of the sample, andB = benzene msoluble matter (see E-2.1 )

ANNEXC[ 7able 1, Sl No. (II) ]

DETERMINATION OF MOISnJRE

c-i APPARATUS

C-1.1 Oven -- mamtamed alI05":t I"C

C-1.2 Weighing Bottle - glass stoppered, shallow

C-2 PROCEDURE

C-2.1 Weigh accurately about 10 g of the well mixedsample m the tared werghmg bottle Drstnbute the

4

sample as evenly as practicable to a depth of about5 rnm Place the bottle contammg thc sample(uncovered) in the oven mamtamed at lOS" :t I"CRemove the bottle from the oven after one hour, closethe bottle promptly and allow It to come to roomtemperature 10 a desiccator Weigh It

C-2.2 Calculate loss on drying, percent by mass

IS 5055 . 1996

ANNEXD(Table I)

DETERMINATION OF PHOSPHORUS

1>-1 REAGEN'IS

D-I.1 AmmoniaSolution -25 percent (wlv)

1>-1.2 Potas~ium Nitrite

0-1.3 Sodium Carbonate - anhydrous

I>-1.4 Magnesium Amino Sulphate

DIssolve 10 g ofmagnesmm sulphate and 20 g of ammo­nium chloride In !\O ml of water and 42 mI of diluteammoma solution set aside for a few days In a well­closed bottle decant and filter

0-1.5 Nitnc Acid - Dtlute

1>-2 PROCEDURE

MIx about 0 5 g, accurately-weighed sample WIth ~ g ofa mixture of equal parts of anhydrous sodium carbonateand potassium rutnte Place the matenal in d crucibleLOverIt with a layer of anhv drous sodium carbonateand igrutc Dissolve the residue III dilute rutne acid andmake It alkaltne WIthammoma solution a nd add a slightexcess of solution of magnesium ammo sulphate dudfilter Wash thc precrpttatc with arnmoma solution (2 '5

percent lillY), igrute and weigh the residue of magnc­sium pyrophosphate (Mg,P,o,) One gram ofthe iesr­due IS equivalent to 0 278 6 g of phosphorus

ANNEXE[ Table 1,Sl No (Ill)]

DETERMINATION OF BENZENE INSOUlBLE MATTER

Eo. PROCEDURE

Soften a poruon of the matenal by warrmng It at a tem­perature not exceeding 60'C and then nux it thoroughlvWeigh 109 of a previously well nu xed sample mto a1 ,O-ml wide-mouth Erlenmeyer flask add Ino m1 ofben­zene and shake until the lecrthm IS dtssolved Frlter thesolunon through a 30 ml Conung C' porosityor equiva­lent filtenng funnel whichpreviously has been dned at

1O,"C for an hour cooled m a desiccator and weighedWash the flask with two successive 2,-ml portions ofbenzene and pass the washings through the filterDry the funnel at 105'C for an hour cool to roomtemperature III a desiccator. and weigh

E-2 CALCULATION

From the gam m mass of the funnel calculate thepercent of the benzene insoluble matter in the sample

ANNEXF[ Table 1.Sl No (IV)]

DETERMINATION OF ACID VALUE

F-l PROCEDURE

Soften a portion ofthe matenal by wamung It in a waterbath at a temperature not exceedtng 60'C and then nux IIthorougWy Transfer about 2 g of the well-rruxed samplemto a 250-00 WIde-mouth Erlenmeyer flask, anddissolve It m 50 ml of petroleum ether To tlus solution,add 50 ml of alcohol, previously neutrahzed to phenol­phthalein WIth 0 I N sodium hydroxide, and mix wellAdd phenolphthalein and titrate WIth 0 I N sodium

5

hydroxide to a pink end point which persists for5 seconds

F-2 CALCUlATION

Calculate the number of rmlhgrarns of potassiumhydroxide required to neutrahze the acids III one gramof the sample by mulnplymg the number of rrulhhtrcs ofo I N sodium hydroxide consumed III the utrauon b) , 0

and dividmg the result by the weight of the sample

IS 5055: '996

ANNEXG[ 7ahle 1, Sf No (VII) 1

DETERMINATION OF HEAVY METAlli

G-' Proceed as given In Annex F of IS ~106 1996except that F-2 3 shall be as follows

To each tube add 10 ml of freshly prepared

hydrogen sulphide, mix and allow to stand for 5nun and view over a white surface The colour ofSolunon B shall not be darker than that ofSolution A

ANNEXH[ 7able 1, stNo (VIII) 1

DETERMINATION OF THE PEROXIDE VALUE

H-4I PRINOPLE

OXidation of potassium Iodide by the peroxides oflecuhm and utranon of the iodine hberated usmgstandard sodium thiosulphate solution

H-I APPARATUS

H-1.1 Analytical Balance

H-I.2 Apparatus - As shown in Fig

H-2 REAGENTS

H-2.1 ALctic Acid GI.lcidl

H-2.2 Chlorofonn

H-2.3 Potassnnn Iodide

boilmg for three to four nunutes Stop heatmg andimmcdrately disconnect the condenser Quickly add 50rnl of water through the glass tube Remove the glasstube and cool the flask to room temperature under thewater tap Titrate With sodium throsulphate until theaqueous layer becomes pale yellow Add I ml ofstarchsolution and continue the titration until the blue colourIS discharged Shake the flask well dunng the titrationto ensure the complete extraction of iodme from thenon-aqueous layer

H-3.4 Obtam a blank turanon value bv repeanng thecomplete procedure (H-3.1 to H-3.3) but WIthout add­mg the sample

H-4 CALCULATION

2 The determmanon should not be earned oul In

.1rong hght

The Perovidc value IU the sample, III rrulllrequrvalentsper kilogram IS given by

/n, = uuual mass m grams ofthe sample taken

NOIL~

J The choice of the concentranon of the sodiumthrosulphate used depends on the anucipated IJITalJon valueII less Ihan 0 3 ml of 0 1 molll sodium thiosulphate" required, repeal the deterrnmalJon usmg 0 0 I mol/lsodium thlo.ulphale

IOOOxaXU,-V,)

/nowhere

I', ~ volume rn rrulhhtrcs oftluosulphate solutionrequired for the titration of the sample

V, = volume III rrnlhhtres ofthiosulphate solutionrequired for the titration at blank.

a = concentration of sodium tluosulphatesolution m molll, and

H-2.4 Sodium Thiosulphate (0 I molll or 00 Imol/l )

0-2.5 Starch Solution (approximately I percent m/v)

H-3 PROCEDURE

H-3. t Place 10 ml of glacial acetic acid and 10 ml ofchloroform In the IOO-ml flask Fit the glass tube andreflux condenser and gently boll the mixture for twominutes to expel all dissolved au Dissolve I g of potas­srum iodide in I 3 ml of water and add this solution tothe nuxture in the flask taking care that the boihng IS notinterrupted

H-3.2 If a yellow colour appears at this stage thedetermmatmn must be rejected and repeated using freshreagents

H-3.3 Accurately weigh, to the nearest mg, about I g ofthe sample and, after a further two mmutes of boihng,add the weighed sample to the contents of the flaskagain taking care that the boihng remains continuousFor this purpose the sample should be contained m anucrobeaker wluch may be lowered through the glasstube With a glass rod. the bottom ot wluch has beenSUItably shaped as shown ID the diagram Thecondenser may be removed for a short I.tme Continue

REFLUX CONDENSER

GLASS TUBE

- LENGTH 250 m m

-10 22mm

ROUND RonOMFLASI< 1100m\)

MICRO BEAKER

- EXT OIA 20mm-HEIGHT.

35m SOmm

IS SUSS: 1996

FIG I J\!>r}\RAl1J' rnR nu, Dru RMINATION OF 1'1 RIIXIIJI VAl IIF

7

Bureau of Indlu Studard.

BIS ISa statutory msUtutlon established under the Bureau oflndion Standards Act. 1986 to promote harmonIousdevelopment of the acUVlUes of standardIzation, markmg and qualIty certification of gooda and attendIng toconnected matters in the country

Copyrlpt

BIS has the copynght oeall ItSpubllcauons No part of these publications may bereproduced In any form WIthOUtthe pnor permrssicn10 wnung of BIS Tlus docs not preclude the free use, 10the course of rmplementmg thestandard, of necessary detaJls, such as symbols and SIzes, type or grade desrgnauons Enqumes relatmg tocopynght beaddressed to the Director (Pubhcanons), SIS

RevIew of Indian Standard.

Amendments are Issued to standards as the need anses on the baSISof comments Standards are also reviewedpenodtcally, a standard along with amendments 15 reaffirmed when such reviewindrcates that no changes arcneeded, If the review 10dlcates that changes arc needed, It IS taken up for revisron Users of Indian Standardsshould ascertalA that they are m possessron of the latest amendments or edmon by referrmg to the latest Issueof 'SIS Handbook' and 'Standards Monthly Addmons'

ThIS Indian Standard has been developed from Doc No FAD 8 (467)

Amendment. baued Since Publication

Amend No Date of Issue

BUREAU OF INDIAN STANDARDS

Text Affected

Headquarters

Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Deihl 110002Telephones 323 0 I 31, 323 94 02, 323 83 75

Regional Offices

Central Manak Shavan, 9 Bahadur Shah Zafar MargNEW DELHI 110002

Eastern 1/14 CIT Scheme VII M, V I P Road, MamktolaCALCUTIA 700054

Northern SCO 335-336, Sector 34-A, CHANDIGARH 160022

Southern CIT Campus, IV Cross Road, MADRAS 600113

Western Manakalaya, E9 MIDC, Marol, Andhen (East)MUMBAI 400093

Telegrams Manaksanstha(Common to

all offices )

Telephone

{32376173233841

{3378499, 33785613378626, 337 8662

{603843602025

{23502 16,23504422351519,2352315

{832 92 95, 832 78 588327891,832 7892

Branches AHMADABAD BANGALORE BHOPAL BHUBANESHWARCOIMSATORE FARIDABAD GHAZIABAD GUWAHATI HYDERABADJAIPUR KANPUR LUCKNOW PATNA THIRUVANANTHAPlJRAM

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