Document e7pJeKLev2mj7Y2zp3bZJ3Dd9

j i S t Ii\ DIRECTIONS FOR TEST NO, 14-15-54 SUBJECT: Total Chlorine In Aroclors. METHOD: Peroxide Fusion R AgNO, titration _______________ REFERENCE: Breamish, Determination of Organlo Halogens, I. & S, C., Anal, Ed, 6, 5, ^52 (1934). Chlorine in Aroclors may be determined by fusion of the sample with sodium peroxide in a Burgess-Parr fusion cup, extracting the fusion with water, acidifying the water extract with nitric acid, and preoipitating the chlorine by addition of an excess of silver nitrate. After fil tration, the excess of silver nitrate is determined by titration against potassium thiocyanate, using ferric am monium sulfate as indicator. Apparatus _ The fusion cup used is the Burgess-Parr Sulfur Bomb No. 3 for flame ignition. A lead gasket is used. For ignition, the bomb is suspended through a round hole in a 1/8" transite plate. This allows the fusion cup to ex tend through the plate for about 5/8inoh. Ignition is effeoted by strongly heating the bottom of the fusion cup with the full flame of a Maker burner for two minutes. Charge for Fusion The fusion mixture is made up of about 15 grams (one metal scoop) of sodium peroxide and 0.0 to 0,3 grams of finely powdered cane.sugar, the amount of cane sugar depending upon the weight of carbon contained in the sample. The reagents should be free from chlorine, or a blank run and corrected accordingly. The fusion mixture is well mixed by placing the ingredients in a small bottle with rubber stop per and shaking vigorously. _. SOLID AROCLORS: The non crystalline type are weighed in the form of small pellets. These are prepared by heating the Aroclor until such a consistency is reaohed as will permit dropping it from a glass stirring rod onto a tinned surface (a can top), each drop forming a pellet. Vflien cool these pellets can be removed from the surface by inserting a spatula under them. .4 grams are used. The pellets are brushed into the bottom of the fusion cup and the fus ion mixture placed on top of them. After tightening the li the oharge is ready for fusion. DSW 330753 STLCOPCB4077397 !* i, i DIRECTIONS FOR TEST NO, H-I3-3A '' v SUBJECT: Total Chlorine in Aroclors__________________ METHOD: Peroxide Fusion ; AgNO, titration REFERENCE; Breamlsh, Determination of Organlo Halogens/ I. & E. C. Anal. Ed. 6. 5, ^52 (19^4). Page No. 2. ` The crystalline type are weighed in the powdered fona. 4 grams being used. They are oharged in the same man- . ner as the*non-crystalline type. LIQUID AROCLORS; .20 to .30 grams are weighed by dropping from a.stirring rod onto a piece of thin hemispherically shaped glass, which has been just previously tared, and which remains on the balance. It is necessary to heat the more viscous aroclors to "dropping" consistency. The pieoe of glass then easily slides off the balance pan in to the fusion cup. * The following quantities of sample, sugar, and AgNO, are used for the respective chlorine contents;- * Cl Content 0.$ r 30? 30# - 45# pjk U b&jo - 70% Weight of`Sample .18 - 20 Grains 28 - .30'Grams .28 - *30 Grams .40 - .41 grams .40 - .41 Grains Amount Sugar AgNO, 0.0 50 cc .15 g. {1/2 scoop) 50 cc .30 g.(l scoop) 50 CO .30 g. 9 75 00 .30 g. " 100 cc 5 Procedure % ' Plaoe the fusion cup, which contains the^prepardd sample and fusion mixture, in the transits ignition plate and apply the 'full flame of the Meker burner to the bottom of the fusion.cup for 2 minutes. (CAUTION; Do not stand too near the fusion during ignitic Then remove-the fiame and cool under the tap. When cool remove screw cap. Thorfughly rinse the cup cover with water, collecting the rinsings in a clean 400 on beaker. Then plaice the fusion cup on its side in the beaker^and cover with a watch glass. 5^ ~ 75 00 be in the beaker from rinsing the cap, and" this is sufficient to decompose the charge. Remove the cup and rinse well. When decompos ition is complete, rinse off oover-glass and add pure DSW 330754 STLCOPCB4077398 5e. DIRECTIONS FOR TEST NO. 14^1 4 SUBJECT; Total Chlorine In Aroclors___________ METHOD: Peroxide Fusion ; AgNOm titration. Page No. 3. ENQS, with stirring,Until aoid is present in excess to the extent of about 10 co. (About 50 oc of aoid are required. ) Add exactly $0, 75 or 100 cc of standard silver nitr.ate sol ution from a pipette (depending upon chlorine present) and stir to effect coagulation of the silver nitrate precipitate Filter with suction through an asbestos pad on a 1-1/2" perforated porcelain plate and wash beaker and filter 4 time H +* with small portions of cold water. Allow the filter to dra completely between wdshings. Transfer the filtrate back in the 400 co beaker and rinse the flask twice, adding the rin sings to the beaker. . Add 5 of ferric iron indicator to the solution and titrat With standard KCNS solution until a distinct pink tint is i just obtained. ` ?' i Calculation of Chlorine Content Subtraot thevolume of KCNS required from the volume of KCNS required tb titrate the. amount of standard AgNO* solution used, ffhis will give the volume of KCNS equivalent, to the chlorine in the sample. Multiply the volume so obtained by the chlorine value of each co of KCNS and divide by the weight of sample taken, t '. . For example? If 50 cc of silver nitrate solution is equiv alent to bl.4 co of KCNS solution and the-value of 1 cc of KCNS solution is .00^770 gram Cl;-then if it is found that 0.3 gram of sample shows a KCNS titration of 10.4 cc the 1 percent of chlorine is: t (61.4 - 10.4) x *005770 x 100 64.09^01 * In case the fusion mixture or other'reagents contain chlori ? the amount must be determined and* deducted from the chlorin j found. `f . DSW 330755 -J- STLCOPCB4077399 DIRECTIONS FOR TEST NO._14*2ii34_______ li SUBJECT: Total Chlorine In Aroclors___________ METHOD: Peroxide Fusion i AgNO. titration. ji l Page No. 4 3^ Solutions Required Standard AgNOm solution: About 0.10 N; dissolve 19*6 grams of silver nitrate in each liter of water. Protect the solution from light. Fifty ec of this solution will precipitate by theory 0.175 gram of ohlorine. i Standard KCNS solution; About 0.08 N; dissolve 8 grams of KCNS in 1 liter of water. 1 oo about . 003 gram chlori Ferric Iron Indicator: Use a saturated solution of ferric i ammonium alum. Pure Nitric Acid, 70^t Stock acid suffices provided it is colorless. It can be boiled in a beaker until color less if necessary. Standardization of Solutions n Weigh 0.3 and 0.15 gram portions of pure dry NaCl into . a separate 600 cc beakers. Add 2^0 cc of distilled water to I each and 10 cc of pure 50^ nitric acid. When solution is fl complete, add 50 cc of standard AgNO, solution from pipette H Stir well and filter through an asbestos mat on a perforate porcelain plate, using suction. Wash filter and transfer the filtrate back to the beaker in the same manner as when i! working with a sample. Titrate the filtrates with s tan dare KCNS solution, using ferric iron indicator. The value of 50 cc of AgNO, solution in terms of KCNS sol ution is found by subtracting the cc of KCNS solution in titrating the 0.3 gram of NaCl from twice the number of cc. of KCNS solution used in titrating the 0.15 gram of NaCl. This value is checked by titrating 50 cc of AgN0B solution added to 4-00 oc of water and 10 cc of pure 50^ HN0,, with *5 KCNS solution. This titration should agree very closely ;i i (jj- 0.1 cc.) with the value found from the titrations of NaCl. The titration must be made slowly to avoid drainage error. DSW 330756 |i STLCOPCB4077400 s I 1 sl ! DIRECTIONS POR TEST NO. 14-1^4 8 \ SUBJECT; Total Chlorine In Aroclors________ \ METHOD; Peroxide Fusion ?A^NO titration Page No. 5 Since pure NaCl contains 6O.665& Cl by theory, the value of the KCNS in terms of chlorine hay be found by dividing the weight of chlorine in the ItfaCl taken by the cc of KCNS equivalent to the silver nitrate required. Example: Two 0,,3 gram portions of NaCl show KCNS tit rations of I3.ll and I3.I3 ce* . Two 0.15 gram portions of NaCl show KCNS titra tions of 37*28 and 37*24 cc. The KCNS equivalent to 5 00 of AgNO* is then (37.28 + 37*24) - 13.12 or 61.4 00. ~ By titration of 50 c of AgNOs against KCNS solution, it is found that 61.36 cc are required. This agrees within .04 00 of the value obtained from the NaCl titrations. The chlorine value of the KCNS is then, .6066 x .3 divided by 61.4 - 13.12 or .OO377O grams Cl per cc of KCNS. The chlorine value may also be calculated from the titratio: of 0.15 gram of NaCl. O.6066 X .15 divided by 61.4 - 37.26 gives .OO377O grains Cl per cc of KCNS. Notes I 1 - The fusion materials have explosive properties if wrongly handled; consequently care must be taken to use safe proportions, to secure a good mixture free of large lumps, and to properly seat the cover of the fusion cup. The fusion mixture must be kept away from water or moist air, either of which may ignite the charge. The fusion mixture should not be ground to reduce lumps* 2 - The method as described is not applicable to volatile I organic compounds unless precautions are taken to avoid I loss of sample during weighing. 3 - On account of the high chlorine content of many of the Aroclors and the small amount of sample taken, great accuracy is required in weighing, transfer, and mixing of the sample. The pupette and burette for measuring the I standard solutions must be very clean to avoid drainage I errors. j DSW 330757 STLCOPCB4077401 i i DIRECTIONS FOR TEST NO.__ U/l^AA SUBJECT; Total Chlorine In AroolorB__________ METHOD: Peroxide Fusion : AgNO titration Page No. 6 4 - Fusions which show black carbon deposites on the eover and side of the fusion cup may or may not give the full ohlorine content. If a carbon deposit is found, a second fusion should be made using a smaller sample or reducing the amount of sugar in the charge or both, 5 - Mixing the fusion charge by shaking after the screw cap has been drawn down may lead to incomplete fusions. The mixing of the sample with the fusion mixture should be done in such a way that the sample is fully covered with the mixture, _ 6 - The temperature at which the standard solutions are standardized should be noted. In case room temperatures vary from this temperature, appropriate volume corrections should be made, 7 - The fusion mixture materials should be essentially free of chlorine. The chlorine content may be determined by making a blank fusion, that is, without addition f sample, and titrating in the usual way. Five cc of AgNO, may be added instead of 50 cc. The KCNS titration is then compared with titrations of 5 cc portions of AgNO* solution in like volumes of solution and nitric acid. Copied/hp IO/I5/34 DSW 330758 STLCOPCB4077402