Document q4koNyRoYBBDRrzpn5MgaZjx

1 DIRSSTia FOR TEST NO, 14-86-41 SUBJECT: METHOD: Free Chlorides In Liquid Aroelors Turbidiaetrie Silver frhlorlde *r***:*!`*r r v*-g }%*? *?*?*" .^smwr "te ^,s ^^Andard^^pSo^i^ Sol^^on| 5 DiaboIt^ Pv660 grams; f,, pure sodltur;,. ehloridein Sufficient watertomeaSureexaotlySOO cc, ; 1 cc, then contains 800 mlerograms Cl, Pipette 25 ee, of this solution to a 500 ec, flask end make up to the nark to give a 0,00113 1| RaCl solution, 1 ee of vhleh eontalns 40 mlerograms of Cl, Preserve ri.n a Pyrex bot tle, Caution: The water used in preparation must be 'chloride free by the Tyndall Beam test; the 0,00113 H solution should not be kept over 1 month, - : . - Sliver Nitrate Solution 10$t Dissolve 5 grass of silver nitrate crystals In 40 ee, of water and add 10 ce, of concentrated nitric acid. : Preparation of Water Extract ^ Transfer 100 ce, of distilled water from a graduate to a clean 250 ee, erlenmeyer flask, Stopper and shake thoroughly. Draw off 50 ee, of the water into a 50 ee, centrifuge tube. Test this water for ehloride by the Tyndall Beam method; a negative result must be obtained before preceding, _ ............... ..... . ............... ...... To the 50 ce, of water remaining in the flask add 200 grams of Aroclor which has been heated to 100*C, Stopper and shake vigorously for at least 20 seconds. Allow to settle. Decant off most of the, water extraet into the 50 ce, centrifuge*tube. Centrifuge until the extract is perfectly clear*". . - The water extraet may alternately be clarified by filtration using suction. In this step the extraet is decanted thru a fritted glass filter funnel of medium porosity which has been coated with a little Johns Manville filter-aid and washed with acetone, dilute ni tric acid, and distilled water until shown by test to be free of chloride, * '. % m^yndall Beam Test Wjg# >? " TraMfcrce, fbf^he; water,extract, clarified by centrifuge. or filtration, to each of two test tubes (LaHOtte l0 ee, color tubes} To one of these add 0,5 eci of the 10$ silver nitrate solution and mix with a plunger-type stirring rod which must be absolutely clean. The solution in the second tube is used as a blank. Compare against other tubes, prepared at the same time, contain ing known amounts of chloride. The knowns are prepared as follows: Dilute exactly 5 ec* of the 0,00133 H NaCl solution to 100 cc. in the volumetric flask; 1 cc, then contains 2 mierograms of Cl, Transfer 1, 2, and 3 ec, portions to similar 10 cc, tubes. Maks up to the 10 ec, mark and add 0,5 cc, of the silver nitrate to each as well as to a fourth tube containing only distilled water such as used in the preparation of the knowns, DSW 330719 STLCOPCB4077363 r. - ................... .. ^ Page No. 2 Test No# 14-38-41 -- Tree Chlorides in Liquid Aroelors 't, 5, 'S - ,'e'. AT .7 \`, tKJ?'*>' * X ,, - ^^^kPV'X'&Sv <''* **-** .(V;\ X^'-'' -, X ' - v'`" , ClK/V, 'V A' r;;-jX Compare the 6 tubes in a dark room where illumination is afforded onlyby a pencil of fright light to proviaethe Tyndall .Besai effeet . Holding;'jfcW tubes^id/thELt the Hghtbnnters Ihe bottom of^Hm^ube at.M an Is' fomotiMS^lfelpful^^dtd ,the kHownSolut ionliS> which nearest matchesthe water extract, estimating to nearest whole microgran# The extract blank and the distilled water should show no turbidity# Calculation - Divide the chloride content -- in micrograms -- of the known solu tion which matches the extract by the weight of Aroelor represented by the extract to obtain chloride content of the. Arodor in p#p#m# ' ,%:;- "Hiv In the procedure described, the lO cc of extract represents 40 grams of Aroelor (1/5 of 200 g#, taken)# The three knowns contain S, 4, and 6 micrograas of Cl, thus representing 0#05, OelO, and 0.15 p#p#n# respectively# Values should, be reported to the nearest 0#025 p.p.m# ' -. -- 1-- - --..- ; ' Precautions ...^ Because of the sensitivity of this test, serious errors may re sult thru very slight contamination or inattention to details# Am monium chloride deposits are common tojlaboratory apparatus# These must be avoided, all containers must be scrupulously cleaned, the ' distilled water must be absolutely.chloride-free, and blank tests applied unremittingly# ~ .. - ABS-p 9/26/41 Sr- DSW 330720 STLCOPCB4077364