A N A L Y T I C A L E DITI 0 N PUBLISHED
BY
THE
AMERICAN
CHEMICAL
SOCIETY
HARRISON
E.
HOWE,
EDITOR
Recommended Specifications for Analytical Reagent Chemicals Hydriodic Acid, Chloroform, Chromium and Potassium Sulfate, Cobalt Nitrate (Not Low in Nickel), Glycerol, 8-Hydroxyquinoline, Lead Carbonate, Manganese Sulfate, Mercury, Sodium Tungstate, Zinc Oxide W. D. COLLINS, H . V. FARR, J. V. FREEMAN, E. F. MARSIGLIO, P. H. RIESSINGER, R . A. OSBORN, JOSEPH ROSIN, E. WICHERS, AND H. H. WILLARD, Committee on Analytical Reagents, .Imerican Chemical Society
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if any, by adding drop by drop 0.1 A’ sodium thiosulfate solution and titrate with standard alkali using phenolphthalein as indicator. NOKVOLATILE MATTER. To 6 cc. of the acid add 2 drops of sulfuric acid, evaporate in a porcelain crucible, and ignite. The weight of the residue should not exceed 0.0010 gram. CHLORIDE AND BROMIDE.Dilute 1.2 cc. to 100 cc. and take aliquots of 5 and 1 cc. To the 1-cc. aliquot, add 0.04 mg. of chloride ion. Dilute each aliquot to 20 cc., add 1 cc. of ammonium hydroxide, and then slowly, with vigorous stirring, add 2 cc. of 5 per cent silver nitrate solution. Heat t o boiling for 5 minutes and stir thoroughly. Cool, shake well, and filter. To the filtrate add nitric acid until neutral and then 1 cc. more. The turbidity in the aliquot of 5 cc. should not be greater than the turbidity in the I-cc. aliquot to n-hich 0.04 mg. of chloride was added. Add 5 cc. of nitric acid to 6 cc. of the acid and PHOSPHORUS. evaaorate on the steam bath until the iodine is volatilized. Take up k i t h 10 cc. of nitric acid, dilute vith 50 cc. of water, and nearly neutralize with ammonium hydroxide. Add 50 cc. of ammonium molybdate solution and shake the solution (at about 40’ C.) for 5 minutes and allow to stand 0.5 hour. Any precipitate formed should not be greater than is produced when a quantity of alkaline phosphate containing 0.03 mg. of phosphorus (P) is treated according t’o the above procedure. SULFATE.Dilute 3 cc. of the acid with 45 cc. of water, new tralize with ammonium hydroxide, add 1 cc. of hydrochloric acid, and heat to boiling. Add 3 cc. of 10 per cent barium chloride solution and allow to stand overnight. If any precipitate is formed, filter, wash thoroughly, ignite, and weigh. The weight of the ignited precipitate should not be more than 0.0013 gram greater than the vieight of the ignited precipitate from a blank test made with the quantities of reagents used in the test, including filtration and ignition. HEAVYMETALS. Treat 1.2 cc. of the acid with 3 cc. of sulfuric acid and volatilize the iodine. Take up in water, neutralize with ammonium hydroxide, and make up to 50 cc. Add 1 CC. of 0.1 N hydrochloric acid and pass hydrogen sulfide through the solution. Estimate lead by comparing with a solution containing the same amounts of sulfuric acid and ammonia, to which have been added 1 cc. of 0.1 N hydrochloric acid and 0.06 mg. of lead. IRON.Dissolve the residue obtained in the test for nonvolatile matter by heating with 2 cc. of hydrochloric acid and 5 drops of nitric acid and dilute to 100 cc. T o 20 cc. add 2 cc. of hydrochloric acid and 2 cc. of 10 per cent ammonium thiocyanate solution. Any red color should not be greater t,han is produced by
HE specifications given below are intended t o serve for
reagents t o be used in careful analytical work. The limits and tests are based on published work, on the experience of members of the committee in the examination of reagent chemicals on the market, and on studies of the tests made by members of the committee as t h e various items were considered. Suggestions for the improvement of the specifications will be welcomed by the committee. In all the directions the acids and ammonium hydroxide referred to are of full strength unless dilution is specified; dilution indicated as (1 3) means 1 volume of the reagent or strong solution with 3 volumes of water; “water” means distilled water of a grade suitable for the test described; reagents used in making the tests are supposed t o be of the grade recommended below or in previous publications (1-11) from the committee. Directions for the preparation of the ammonium molybdate solution are given under the test for phosphate in ammonium nitrate ( 3 ) . A time of 5 minutes is to be allowed for the appearance of precipitates and before observation of color reactions, unless some other time is specified. Blank tests must be made on water and all reagents used in the tests unless the directions provide for elimination of errors due t o impurities. Solutions of samples must be filtered for tests in which insoluble matter would interfere.
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Acid Hydriodic Requirements
ASAY. Not less than 54 per cent HI. NONVOLATILE MATTER. Not more than 0.010 per cent. CHLORIDE AND BROMIDE (ASCl). h-ot more than 0.05 per cent. PHOSPHORUS (P). Kot more than 0.0003 per cent. SULFATE (Soh). Not more than 0.01 per cent. HEAVYhqETALs (as Pb). Not more than 0.003 per cent. IRON (Fe). Xot more than 0.002 per cent. Tests
ASSAY. Weigh a suitable quantity of the acid; dilute with about 30 times its weight of vater: discharge the yellow color, 631
632
VOL. 12, NO. 11
INDUSTRIAL AND ENGINEERING CHERIISTRY
0.04 mg. of iron in the same volume of a solution containing the quantities of reagents used in the test.
Chloroform NOTE. Chloroform should be supplied and stored in amber glass containers and protected from direct sunlight. Requirements
SPECIFIC GRAVITY AT 25"/25O C.
1.475 to 1.478.
KONVOLATILE MATTER. Kot more than 0.001 per cent.
ACETONE OR ALDEHYDE. To pass test [limit about 0.005 per cent as (CH&CO]. ACIDAND CHLORIDE.To pass test. FREE CHLORINE (Cl). To pass test. SUBSTANCES DARKENED BY SCLFURICID. To pass test. Tests
NONVOLATILE MATTER. Evaporate 67 cc. (100 grams) on the steam bath and dry the residue a t 105' to 110" C. for 0.5 hour. The weight of the residue should not exceed 0.0010 gram. ACETONE OR ALDEHYDE.Agitate 3 cc. with 10 cc. of ammoniafree distilled water in a glass-stoppered cylinder for 5 minutes. After the liquids separate, transfer 5 cc. of the water extract to another glass-stoppered cylinder containing 40 cc. of ammoniafree distilled water, and add 5 cc. of Nessler's solution. No turbidity nor precipitate should develop within 1 minute (aldehydes and ketones). ACIDAND CHLORIDE.Shake 17 cc. with 25 cc. of viater for 5 minutes, allow the liquids to separate, and draw off the water. 10 cc. should not redden blue litmus paper. Treat another 10 cc. of the water with 5 drops of 0.1 N silver nitrate. No turbidity should be produced. FREECHLORINE. Shake gently 10 cc. for 2 minutes with 10 cc. of water to which 2 drops each of 10 per cent potassium iodide solution and starch solution have been added and allow to separate. The lower layer should not be colored. SUBSTANCES DARKENED BY SULFURIC ACID. Shake 20 cc. with 5 cc. of sulfuric acid for 5 minutes in a glass-stoppered cylinder which has been rinsed with sulfuric acid. After the layers have separated the sulfuric acid should be colorless or practically so.
Chromium and Potassium Sulfate Requirements
INSOLUBLE MATTER. Not more than 0.010 per cent.
CHLORIDE (Cl). To pass test (limit about 0.002 per cent). ALUMINUM (Al). Not more than 0.02 per cent. T o pass test (limit about 0.010 per cent). AMMONIA ("3). HEAVY METALS. Kot more than 0.015 per cent as sulfates. IRON (Fe). Not more than 0.02 per cent. Tests
IXSOLUBLE MATTER. Dissolve 10 grams in 100 cc. of water and allow to stand on the steam bath for 1 hour. Filter through asbestos in a Gooch crucible, wash thoroughly, dry a t 105' C., and weigh. The weight of the residue should not exceed 0.0010 gram. CHLORIDE.Dissolve 0.2 gram in 20 cc. of water and divide nto two portions. To one portion add 1 cc. of nitric acid and 1 cc. of 0.1 N silver nitrate, To the other portion add the same volume of nitric acid and 1 cc. of water. S o appreciable difference should be apparent in the clearness of the two solutions. ALUMINUM.Dissolve 4 grams in 100 cc. of water. Carefully add 4 grams of sodium peroxide. Heat the solution to boiling, filter, and wash m-ith a small quantity of hot water. (Retain the residue on the filter for the test for iron.) Add hydrochloric acid to the filtrate to distinct acid reaction, then add a slight excess of ammonium hydroxide, and boil until the odor of ammonia is no longer perceptible. Filter, wash thoroughly with hot water until the washings are colorless, and ignite. The weight of the ignited precipitate should not exceed 0.0015 gram. AMMONIA.To a solution of 0.25 gram of the sample in 10 cc. of water add 10 cc. of 10 per cent sodium hydroxide solution and heat in a flask on the steam bath, taking care that the solution does not come in contact with the rim of the flask. A piece of red litmus paper moistened and placed across the mouth of the flask should not turn blue within 0.5 minute. HEAVY METALS. Dissolve 100 grams in 200 cc. of water; add 20 to 50 mg. of mercuric chloride, and 2 cc. of N hydrochloric acid. Filter and pass hydrogen sulfide through the filtrate for
5 minutes. Let stand for 10 minutes, filter, wash, burn off the paper under a well ventilated hood, add 1 drop of sulfuric acid, ignite, and weigh. The weight of the residue should not exceed 0.0015 gram. IRON.Wash viith hot water the residue remaining on the filter in the test for aluminum until the washings are colorless. Dissolve the residue from the filter with 5 cc. of hydrochloric acid (1 1) and wash the filter paper with hot water. Cool and dilute to 80 cc. To 10 cc. add 10 cc. of water, 2 cc. of hydrochloric acid, and 2 cc. of 10 per cent ammonium thiocyanate solution. .4ny red color should not be greater than is produced by 0.1 mg. of iron in an equal volume of solution containing the quantities of reagents used in the test.
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Cobalt Xitrate (Xot Low in Sickel) Requirements
ISSOLUBLE MATTER. Not more than 0.010 per cent. CHLORIDE ((21). Kot more than 0.005 per cent. (SO4). S o t more than 0.010 per cent. SULFATE A L K ~ L I E~ PS ; DEARTHS (as S U L F ~ T E S )Not . more than 0 2.5 per cent. COPPER. To pass test (limit about 0.005 per cent). IRON (Fe). Kot more than 0.005 per cent. NICKEL(Ni). S o t more than 0.50 per cent. Tests
5 grams in 50 cc. of hot water INSOLUBLE ~ I A T T E RDissolve . and allow to stand on the steam bath for 1 hour. Filter on asbestos in a Gooch crucible, wash thoroughly, dry a t 100" to 105' C. and neigh. The weight of the residue should not exceed 0.0005 gram. CHLORIDE.Dissolve 1 gram in 20 cc. of water and divide into 2 equal portions. To 1 portion add 1 drop of 0.1 N hydrochloric acid, 1 cc. of nitric acid, and 1 cc. of 0.1 N silver nitrate. Allow to stand 10 minutes, filter without xmhing, and add 0.025 mg. of chloride ion. The oreciDitate should be greater than is formed in the other portion or; theaddition of 1 cc. i f nitric acid and 1 cc. of 0.1 N silver nitrate. SULFATE. Treat 5 grams with 10 cc. of water and 10 cc. of hydrochloric acid and evaporate to dryness on a steam bath. Redissolve the residue in about 5 cc. of hot Tvater and 10 cc. of hydrochloric acid and re-evaporate to dryness. Dissolve the residue in 100 cc. of water and 1 cc. of hydrochloric acid and filter. Heat t,he filtrate to boiling, add 5 cc. of 10 per cent barium chloride solution, and allow to stand overnight. If a precipitate is present, filter, wash, and ignite. The weight of the ignited precipitate should not be more than 0.0012 gram greater than the weight obtained in a blank test Jr-ith the same quantities of reagents following the same procedure, including filtration. ALKALIES AND EARTHS. Dissolve 2 grams of the sample and 1 gram of ammonium chloride in 20 cc. of dilute ammonium hydroxide (1 3), dilute to 90 cc., and pass hydrogen sulfide until the cobalt is all precipitated. A4ddsufficient water to make the total volume 100 cc., mix well, and filter. Evaporate 50 cc. of the filtrate nearly to dryness, add 0.5 cc. of sulfuric acid, ignite, and weigh the residue. The weight of the residue should not exceed 0.0025 gram. COPPER. Solution T o . 1. Dissolve 1 gram in 30 cc. of water and add 0.5 cc. of nitric acid. Dissolve 1 gram in 20 cc. of water, add 0.5 cc. of nitric acid, cool to about 15' C., and add 10 cc. of saturated hydrogen sulfide water. KOchange in color should be noticeable when compared with solution Nor 1. IROP;.Dissolve 1 gram in 20 cc. of lr-ater, and add 1 gram of ammonium chloride and sufficient ammonlum hydroxide to dissolve the precipitate first formed. Filter and wash until the filtrate is colorless. Drop on the filter 5 cc. of hot dilute hydrochloric acid (1 1) and wash with hot water until the filtrate and washinns measure about 45 cc. Cool, add 5 cc. of a 10 per cent ammoKium thiocyanate solution, dilute to 50 cc., and mix well. Any red color should not be greater than in a control test made with the same volume of water and hydrochloric acid to which 0.05 mg. of ferric iron has been added. NICKEL. Dissolve 0.5 gram in 70 cc. of water, add 3 grams of sodium acetate and 2 drops of acetic acid, and boil for 5 minutes. Filter while hot and Rash with 10 cc. of hot Ivater. Allow the filtrate to cool and render it slightly alkaline by carefully adding 1 or 2 drops of ammonium hydroxide. Add 60 cc. of a 1 per cent alcoholic solution of dimethylglyoxime and allow to stand overnight. Filter through a weighed Gooch crucible, wash with alcohol, and dry a t 100" C. The increase in weight should not exceed 0.0125 gram.
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633
ANALYTICAL EDITION
KOVEMBER 15, 1940
Glycerol Requirements
COLOR. To pass test. AT 25'/25' c. Not less than 1.250 per cent. SPECIFIC GRAVITY NONVOLATILE MATTER. Kot more than 0.005 per cent. NEUTRALITY.To pass test. CHLORIDE (Cl). Not more than 0.001 per cent. SULFATE (SO4). To pass test (limit about 0.002 per cent). FATTY ACID ESTERS. To pass test (limit about 0.07 per cent as glycerol butyrate). SILVER-REDUCING SUBSTANCES. To pass test. SUBSTANCES DARKEKED BY SULFURIC ACID. To pass test. To pass test (limit about 0.0008 per cent as HEAVYMETALS. lead or iron). Tests
COLOR. The color of glycerol when viewed downwards against a white surface in a 50-cc. Nessler tube should not be darker than the color of a standard made by diluting 0.3 cc. of ferric chloride color solution (see note) to 50 cc. in a Nessler tube of the same diameter as that containing the glycerol. SPECIFIC GRAVITY AT 25"/25" C. This value should be determined with a pycnometer a t 25" C. and be not less than 1.250, corresponding to about 96 per cent glycerol. NONVOLATILE MATTER. Heat 20 grams in an o en dish, ignite the vapors, and when the glycerol has been entireg consumed ignite a t a low red heat. The weight of the residue should not exceed 0.0010 gram. NEUTRALITY.A 10 per cent aqueous solution of glycerol should not affect the color of either red or blue litmus paper in 1 minute. CHLORIDE.Dilute 5 grams with 30 cc. of water, and add 1 cc. of nitric acid and 1 cc. of 0.1 N silver nitrate solution. Any turbidity should not be greater than that produced by 0.05 mg. of chloride ion in an equal volume of solution containing the quantities of reagents used in the test. SULFATE. Dilute 5 grams with 25 cc. of water, and add 1 cc. of 0.1 N hydrochloric acid and 2 cc. of 10 per cent barium chloride solution. Any turbidity should not be greater than is produced by 0.01 mg. of sulfate ion in an equal volume of solution containing the quantities of reagents used in the test, comparison being made after the sample and standard have stood for 20 minutes. FATTY ACIDESTERS. Weigh 40 grams into a 250-cc. Erlenmeyer flask and add 50 cc. of freshly boiled hot distilled water. Add 10 cc. of 0.1 N sodium hydroxide solution, cover with a loosely fitting ear shaped bulb, and leave on the steam bath for 45 minutes. 8ooland titrate the excess alkali with 0.1 N hydrochloric acid, using 3 drops of bromothymol blue solution as indicator and titrating to a bluish-green end point. Run a blank with 50 cc. of the same water and 10 cc. of the 0.1 N sodium hydroxide solution, heating it for the same length of time and titrating to the same bluish-green end point with 0.1 N hydrochloric acid. The difference in the amount of acid used in the blank and in the titration of the sample should be less than 3.00 cc. SILVER-REDCCING SUBSTAKCES. Mix 10 cc. with 10 cc. of 10 per cent ammonium hydroxide. Heat to 60" C., add 0.5 cc. of 0.1 N silver nitrate solution, and allon- to stand in the dark for 5 minutes in a jar of water at 60" C. The color produced should be less than the color produced when hydrogen sulfide is passed through 25 cc. of a solution containing 1 gram of sodium sulfate and 0.04 mg. of lead. SUBSTANCES DARKENEDBY SULFURICACID. Vigorously shake 5 cc. of glycerol with 5 cc. of sulfuric acid in a glassstoppered 25-cc. cylinder for 1 minute and allow the liquid to stand for 1 hour. The liquid should not be darker than a standard made up of 0.4 cc. of cobaltous chloride color solution, 3.0 cc. of ferric chloride color solution, and 6.60 cc. of distilled Tvater (see note for preparation of color solutions). HEAVYMETALS. Dilute 2 grams with 10 cc. of water, add 1 cc. of 0.1 N hydrochloric acid and 5 cc. of hydrogen sulfide water, and render alkaline with ammonium hydroxide. KO darkening should be observed. IYOTE. COLOR SOLUTIONS. Ferric Chloride Color Solution. Ferric chloride is dissolved in a mixture of 25 volumes of hydrochloric acid and 975 volumes of water and the strength adjusted so that the iron content corresponds to 45.05 mg. of FeC13.6HzO per cc. Cobaltous Chloride Color Solution. Cobaltous chloride is dissolved in a mixture of 25 volumes of hydrochloric acid and 975 volumes of water and the strength adjusted so that the cobalt content corresponds to 59.5 mg. of CoC12. 6H20per cc.
8-H ydroxyquinoline Requirements
MELTISGPOIKT RAKGE. 72.5" to 73.5" C. INSOLUBLE IN ALCOHOL. iYot more than 0.050 per cent. Not more than 0.50 per cent. RESIDUE ON IGXITION. SULFATE (SOa). To pass test (limit about 0.02 per cent). SUITABILITY FOR MAGNESIUM DETERMINATIONS. To pass test. Tests
MELTINGPOINT RANGE. Determine by the E.S. Pharmacopeia method. INSOLUBLE IK ALCOHOL.Dissolve 3 grams in 40 cc. of alcohol, flter through a Gooch crucible, wash with 95 per cent alcohol, dry a t 105" to 110" C., and weigh. The weight of the insoluble material should not exceed 0.0015 gram. RESIDUEO N IGNITION. Ignite 1 gram. The weight of the residue should not exceed 0.0005 gram. SULFATE.Dissolve 1 gram in 1 cc. of hydrochloric acid and dilute with 20 cc. of water. Heat to boiling and add 1 cc. of barium chloride solution. No turbidity should be observed after standing for 30 minutes. SUITABILITY FOR MAGNESIUM DETERMINATIONS. Dissolve 0.50 gram of magnesium chloride (iMgCL.GHz0) in water containing 1 cc. of dilute hydrochloric acid (1 1) and make t o a volume of 100 cc. Dilute 10 cc. of the solution to 50 cc. and add 3.5 cc. of a solution of the 8-hydroxyquinoline prepared by dissolving 2.5 grams in 5 cc. of warm acetic acid and pouring into 95 cc. of water a t 60' C. Heat t o 80" C., add with stirring 2 cc. of ammonium hydroxide, allow to cool for 10 minutes, and filter. The filtrate should be yellow and alkaline and should yield a yellow precipitate when 5 cc. of the magnesium chloride solution are added and the whole is warmed.
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Lead Carbonate Requirements
INSOLEBLE IN ACETIC ACID. Not more than 0.03 per cent. CHLORIDE (Cl). h'ot more than 0.005 per cent. KITRATE(NOs). To pass test (limit about 0.005 per cent). ALKALIES AND ALKALINEEARTHS. Not more than 0.20 per cent as sulfates. IRON (Fe). Not more than 0.005 per cent. ZINC(Zn). To pass test (limit about 0.005 per cent). Tests
ISSOLUBLE IS ACETICACID. Dissolve 5 grams by heating on a steam bath for 1 hour with a mixture of 50 cc. of water and 7 cc. of acetic acid. If an insoluble residue remains, filter and wash with a mixture of 100 volumes of water and 2 cc. of acetic acid. Dry a t 105' to 110" C. The weight of the residue should not exceed 0.0016 gram. CHLORIDE.Dissolve 1 gram in 20 cc. of 10 per cent nitric acid and filter if solution is not perfectly clear. Add 1 cc. of 0.1 N silver nitrate solution. Any opaiescence should not be greater than that produced by 0.05 nig. of chloride ion in a n equal volume of water containing the quantities of reagents used in the test. NITRATE. Dissolve 1 gram in 7 cc. of water, 1 cc. of sodium chloride solution containing 5 mg. of NaCl per cc., and 2 cc. of acetic acid. If necessary heat on the steam bath to dissolve the sample. Cool and dilute to 30 cc. To 10 cc. add 0.20 cc. of indigo carmine solution (1 in 1000) and 10 cc. of sulfuric acid. Stir thoroughly and allow to stand for 10 minutes. The blue color should not be completely discharged. ALKALIESAND ALKALINEEARTHS.Dissolve 2 grams by heating with a mixture of 20 cc. of water and 3 cc. of nitric acid. Dilute to 100 cc. with water and precipitate the lead completely with hydrogen sulfide. Filter. To 50 cc. of the filtrate add a few drops of sulfuric acid, evaporate to dryness, and ignite. The weight of the residue should not exceed 0.0020 gram. IRON.Warm the residue obtained in the test for alkalies and alkaline earths with 1 cc. of hydrochloric acid and 2 drops of nitric acid. Dilute t o 20 cc. with water; add 2 cc. of hydrochloric acid and 3 cc. of 10 per cent ammonium thiocyanate solution. Any red color should not be greater than is produced in a control test made with 0.05 mg. of iron. ZINC. Dissolve 3 grams in a mixture of 25 cc. of water and 5 cc. of acetic acid. Dilute with water to 42 cc. Add with stirring 3 cc. of sulfuric acid, and filter. To 30 cc. of the filtrate add 5 drops of nitric acid; heat to boiling and pour into a mixture of 10 cc. of ammonium hydroxide and 20 cc. of water. Filter while hot and wash with 2 cc. of hot water. Xeutraliee with
acetic acid, then add 1 cc. more of the acid. Cool and add 2 cc. of a freshly prepared 10 per cent solution of potassium ferrocyanide. No turbidity should appear in 10 minutes.
Manganese Sulfate Requirements
WATEROF CRYSTALLIZATION. 32 to 38 per cent. INSOLUBLE MATTER. Xot more than 0,010 per cent, CHLORIDE ((31). Kot more than 0.005 per cent. ALKALIES AKD ALKALISE EARTHS. Not more than 0.25 per cent. I R O X (Fe). Kot more than 0.002 per cent, HEAVYMETALSAS Pb. To pass test' (limit about 0.001 per cent). NICKEL(Xi). r o t more than 0.05 per cent. ZINC(Zn). To pass test. SUBSTANCES REDUCIKG PER31.4NQAn,4TE. T O pass t,eSt. Tests
WATER OF CRYSTALLIZATION. Weigh accurately about 2 grams. Heat a t 150" C. for a few hours, then ignite a t about 400" to 500" C. to constant m-eight. The loss in weight should be from 32 to 38 per cent. INSOLUBLE MATTER. Dissolve 10 grams in 100 cc. of hot water and allow to stand on the steam bath for 1 hour. Filter on asbestos in a Gooch crucible, wash thoroughly, and dry at 105' to 110' C. The neight of the residue should not exceed 0.0010 gram. CHLORIDE.Dissolve 1 gram in 20 cc. of water, and add 1 cc. of nitric acid and 1 cc. of 0.1 F silver nitrate. Any turbidity should not be greater than is produced by 0.05 mg. of chloride ion in an equal volume of water with the quant,ities of nitric acid and silver nitrate used in the test. ALKALIESAKD ALKALIKEEARTHS. Dissolve 2 grams in about 90 cc. of water and precipitate the manganese by adding sufficient fresh ammonium sulfide solution. Heat on the mater bath for about 0.5 hour, cool, dilute with water to 100 cc., mix well, and filter. Evaporate 50 cc. of the filtrate to dryness, ignite, and weigh the residue. The weight - of the residue should not exceed 0.00125 gram. IRON.Dissolve 1 gram in 15 cc. of water, add a drop of nitric acid. and heat to boiling. Cool and dilute with water to 15 cc. Add'2 cc. of hydrochloric acid and 3 cc. of 10 per cent ammonium thiocyanate solution. Any red color produced should not be greater than that produced in a control test made with 0.02 mg. of iron. HEAVY METALS. S'olutzon KO,1. Dissolve 1 gram of the manganese sulfate in 20 cc. of mater and add 1 cc. of 1 A' hydrochlonc acid. Dissolve 1 gram of the manganese sulfate in 10 cc. of water, add 1cc. of 1I\i hydrochloric acid and 10 cc. of saturated hydrogen sulfide water. No change in color should be noticeable when compared with solution No. 1. NICKEL. Dissolve 1 gram in 200 cc. of n-ater. Dissolve 2 grams of sodium acetate in 20 cc. of the solution and add 10 cc. of hydrogen sulfide m-ater. After 1 minute, add 5 cc. of glacial acetic acid. Any darkening should not be greater than in a blank to which 0.05 mg. of nickel has been added. ZINC. Dissolve 1 gram in 20 ec. of water. To 10 cc. of the solution add 10 cc. of hydrogen sulfide water. No turbidity which is cleared up by hydrochloric acid should be produced in 2 minutes. Dissolve 10 grams SUBSTANCES REDUCIXG PERMANGANATE. in 200 cc. of water. Add 3 cc. each of sulfuric acid and phoshoric acid, then add 0.1 cc. of 0.1 N potassium permanganate. $he pink color should persist for 1 minute, correction being made for any blank on the reagents.
Mercury Requirements
APPEARANCE. To pass test. BASEMETALS. To pass test (limit to about 0.0001 per cent). GOLDAND SILVER. Not more than 0.005 per cent.
Tests APPEARANCE.The mercury shall have a bright mirrorlike surface free from film or scum. It shall pour freely from a thoroughlv clean, dry glass container without leaving any mercury aahehng to t h e - g l k BASEMETALS. Weigh 10 to 20 grams into a tared porcelain crucible. Evaporate the mercury from a hot plate, in a well-
ventilated hood, without permitting the mercury to hoil. The mercury shall retain its bright mirrorlike surface and should not develop any film or scum. GOLDASD SILVER.-4fter the mercury in the preceding teat. has evaporated, ignite the crucible a t a dull red heat for 5 minutes, making sure that mercury which has condensed on the \rails of the crucible is driven off. The weight of the residue 4ould not exceed 0.005 per cent of the weight of the sample.
Sodium Tungstate Requirements
IS~OLUBLE MATTER. Kot more than 0.015 per cent. ALKALISITY. Not more than 0.20 per cent as Na&03. CHLORIDE (Cl). Rot more than 0.01 per cent. MOLYBDENCnI (Mo). Not more than 0.001 per cent. SITROGEN Conwoums (as N). Xot more than 0.002 per cent, SULFATE (SOJ. S o t more than 0.01 per cent. HE.AVYMETALS. To pass test (limit ahout, 0.0005 per cent lead, ahout 0.0005 per cent iron). Tests
ITKILL-BLE MATTER. Dissolve 10 grams in 100 cc. of water :tnd digest on the steam bath for 1 hour. Filter through a tared Gooch crucible, wash, dry a t 105" C., and neigh. The weight of the residue should not exceed 0.0015 gram. ALXALIXITY.Dissolve 2 grams in 50 cc. of cold water and add 2 drops of phenolphthalein solution. A pink color should be produced xhich should be discharged by the addition of not more than 0.4 cc. of 0.1 1V acid. CHLORIDE.Dissolve 1 gram in 25 CC. of water and bring to a boil. Add 15 cc. of a solution containing 5 cc. of nitric acid and 10 cc. of water in which is dissolved 0.1 gram of cinchonine alkaloid. Continue to boil for 5 minutes, cool, dilute to 50 cc., mix well, and filter, To 10 cc. of the filtrate add 1 cc. of 0.1 N silver nitrate. Any turbidity in 2 minutes should not be greater than IS produced by 0.02 mg. of chloride ion in an equal volume of solution containing the uantities of reagents used in the test. MOLYBDEXUnI. Dissave 2 grams in 10 cc. of water and make slightly alkaline if necessary with dilute sodium hydroxide. Dissolve in this solution 0.5 gram of potassium xanthate without warming. Add 10 cc. of chloroform, then add, drop by drop, dilute sulfuric acid (1 9), shaking after each addition until the color in the chloroform is no longer intensified. Any color should not be greater than is produced by 0.03 mg. of molybdic anhydride (corresponding to 0.02 mg. of molybdenum) in an equal volume of solution containing the quantities of reagents used in the test. SITROGEN CONPOCNDS.Dissolve 4 grams in 40 cc. of water and add 20 cc. of 10 per cent sodium hydroxide solution and 0.5 gram of aluminum wire. Let stand 3 hours protected from loss or absorption of ammonia. Decant 30 cc. and add 2 cc. of Xessler's solution. Any color should not be greater than is produced by a quantity of an ammonium salt' corresponding to 0.04 mg. of nitrogen in an equal volume of solution containing the quantities of reagents used in the test. SGLFATE.Dissolve 2 grams in 100 cc. of water and add slowly with stirring 5 cc. of hydrochloric acid. Evaporate to dryness and heat for 20 minutes at 110' C. -4dd 30 cc. of water, 2.5 cc. of hydrochloric acid, and 2 cc. of cinchonine solution [made by dissolving 5 grams of cinchonine in 50 cc. of dilute hydrochloric acid (1 3)] and heat just below the boiling point for 30 minutes. Dilute to 30 cc. and allow to stand until cool. Filter and to Id cc. of the filtrate add ammonium hydroxide a drop at a time until a permanent precipitate forms. Add just sufficient hydrochloric acid to redissolve the precipitate and add 5 cc. of 10 per cent barium chloride solution. Any turbidity should not be greater than is produced by 0.1 mg. of sulfate ion in an equal volume of solution containing the quantities of reagents used in the test. HEAVYMETALS. Dissolve 2 rams in 20 cc. of water. Add 2 cc. of ammonium hydroxide a n f 5 cc. of hydrogen sulfide water. There should be no brown coloration and any green coloration should not be greater than is produced by 0.01 mg. of iron in an equal volume of solution containing the quantities of reagents used in the test.
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Zinc Oxide Requirements
INSOLUBLE IX SULFURIC ACID. Not more than 0.010 per cent. ALKALINITY.To pass test. CHLORIDE(CI). Not more than 0.001 per cent. NITRATE(NOa). To pass test (limit about 0.003 per cent).
NO\.-EhlBER 15. 1940
ANALYTICAL E D I T I O h
SULFUR Cohrporsns 9s Sod. Not more than 0.010 per cent. ARSEXIC(As). Not more than 0.0002 per cent. IRON (Fe). To pass test (limit about 0.001 per cent). LEAD(Pb). Not more than 0.005 per cent. (’Mn). Pl-ot more than 0.0005 per cent. MAXGANESE SUBGTAKCES N O T PRECIPITATED BY AvhioxInni SULFIDE. Not more than 0.10 per cent.
635
.elution (1 in 1000) in place of 1 drop of indigo solution (1 in 1000). I n nearly all instances this rhange makes no difference in the result of the test. T h e change is printed for those tests in which there is some other modification of t h e test or the limit.
Acetone (2) Tests
ASSAY. Omit the assay of this reagent.
INSOLUBLE IN SULFURIC ACID. Dissolve 10 grams by heating on a steam bath for 1 hour with a mixture of 10 cc. of sulfuric acid and 150 cc. of water. Filter through asbestos in a Gooch crucible, wash thoroughly, and dry a t 105’ t o llO°C. The weight of the insoluble residue should not exceed 0.0010 gram. Boil 2 grams with 20 cc. of water for 1 minute ALKALINITY. and filter. Add 2 drops of phenolphthalein solution to 10 cc. of the filtrate. KO red color should be produced. CHLORIDE.Dissolve 1 gram in 10 cc. of water and 3 cc. of nitric acid; filter, if necessary, and add 1 cc. of 0.1 N silver nitrate. Any turbidity should not be greater than is produced by 0.01 mg. of chloride ion in an equal volume of solution containing the quantities of reagents used in the test. NITRATE. Dissolve 1 gram in a mixture of 35 cc. of water and 15 cc. of sulfuric acid and add to the solution while still hot 0.20 cc. of indigo carmine solution (1 in 1000). The blue color should not be destroyed in 5 minutes. SULFURCOMPOUSDS.Mix 5 grams with 50 cc. of water, and add about 0.05 gram of sodium carbonate and 1 cc. of saturated bromine water. Boil for 5 minutes, cautiously add hydrochloric acid in small portions until the zinc oxide is dissolved, then add 1 cc. more of the hydrochloric acid. Filter, wash, and dilute the filtrate with m t e r to about 150 cc. Heat t o boiling, add 5 cc. of 10 per cent barium chloride solution, heat on the steam bath for 2 hours, and allow to stand overnight. If any precipitate is formed, filter, wash with water containing a small quantity of hydrochloric acid, then wash with water alone, ignite, and weigh. The weight of the ignited precipitate should not be more than 0.0013 gram greater than the weight obtained in a blank test made with the same quantities of reagents and including filtration and ignition of the paper. ARSENIC. Test 2 grams by the Gutzeit method. IRON. Dissolve 1 gram in a mixture of 5 cc. of hydrochloric acid and 5 cc. of water. Add 2 drops of nitric acid, bring t o a boil, and cool. Add 2 cc. of 10 per cent ammonium thiocyanate solution and sufficient water t o make 15 cc. Any red color should not be greater than that produced by 0.01 mg. of ferric iron in 15 cc. of hydrochloric acid (1 2) when 2 cc. of 10 per cent ammonium thiocyanate solution are added. LEAD. Add 2 grams to 20 cc. of distilled water and after stirring well add 5 cc. of acetic acid and warm until solution is effected. Filter, if necessary, and add 1 cc. of 10 per cent potassium chromate solution. Any turbidity or precipitate should not be greater than is produced by 0.10 mg. of lead in an equal volume of solution containing 2 cc. of acetic acid to which 1 cc. of 10 per cent potassium chromate has been added. Comparison should be made after 10 minutes. 2 grams in 10 cc. of water and 5 cc. ~ I A K G A N E SDissolve E. of nitric acid, using a n Erlenmeyer flask. Add 1 cc. of 0.1 N silver nitrate solution. Boil gently for 1 minute. Add 5 cc. of 10 per cent ammonium ersulfate solution and keep a t about 1000 C. for 5 minutes. 001 the solution in the flask, adjust to 25 cc., and observe in a tube. S n y pink color should not be darker than that produced by 0.01 mg. of manganese which has been treated with the same volume of reagents a t the same time as the sample under analysis. SUBSTAXCES NOTPRECIPITATED B Y AaruoiiIuM SULFIDE. Dissolve 2 grams by warming with a mixture of 15 cc. of water and 5 cc. of acetic acid. Dilute with water to 150 cc. and pass hydrogen sulfide throu h the solution until all the zinc is precipitated. Add 1 ce. o f ammonium hydroxide and pass hydrogen sulfide for 2 minutes longer. Filter, evaporate 75 cc. of the filtrate nearly t o dryness, add 0.5 cc. of sulfuric acid, evaporate and ignite. The Tyeight of the ignited residue should not exceed 0.0010 gram.
+
8
Acid Formic ( 1 1 ) Requirement
ASSAY. Xot less than 85 per cent.
Acid Phosphoric (4) Test
IRON. Dilute 4 cc. to 100 cc., take 5 cc. of this solution, and dilute to 40 cc. Add 2 cc. of ammonium hydroxide and 5 cc. of
freshly prepared hydrogen sulfide water. Any color produced should not be more than is produced in a standard containing 1.25 cc. of the same diluted phosphoric acid, 0.0125 mg. of iron, and the same quantities of reagents, in the same volume.
Acid Sulfuric ( 1 ) Test
NITRATE. Add 10 cc. t o 5 cc. of water containing 0.10 cc. of indigo carmine solution (1 in 1000). The blue color should not be completely discharged in 5 minutes.
Aluminum and Potassium Sulfate (2) Requirements
IXSOLUBLE MATTER. Not more than 0.010 per cent.
AMMONIA (NEI,). Not more than 0.02 per cent. HEAVY METALS. T o pass test (limit about 0.002 per cent lead). Tests
ISSOLUBLE MATTER. The weight of the residue should not exceed 0.0010 gram. CHLORIDE.Cool the solution before the addition of silver nitrate. AmiosI.4. Dissolve 0.100 gram in 50 cc. of m:itcr, add sodium hydroxide solution to redissolve the precipitate first formed, and then add 2 cc. of Nessler’s solution. The color should not be more than is produced by a quantity of ammonium salt corresponding to 0.02 mg. of SHa in an equal volume of solution containing the quantities of sodium hydroxide and Nessler’s solution used in the test. HEAVYMETALS. Dissolve 1 gram in 50 cc. of water and pass hydrogen sulfide through the solution. The color produced should not be greater than that resulting from passing hydrogen sulfide through 50 cc. of n-ater containing 0.02 mg. of lead and 1 cc. of 0.1 N hydrochloric acid.
Ammonium Acetate (2) Test
NITRATE. Dissolve 3 grams in 8 cc. of water, and add 2 cc. of a sodium chloride solution containing 5 mg. of S a c 1 per cc., 0.10 cc. of indigo carmine solution (1 in lOOO), and 10 cc. of sulfuric acid. The blue color should not be completely discharged in 5 minutes.
Ammonium Carbonate (2) Test
NOXVOLATILE MSTTER. fore heating.
Add 5 cc. of water to the sample be-
Corrections for Published Specifications
Ammonium Hydroxide ( I )
The corrections and modifications of published specifications giren below have been adopted as t h e result of comments b y members of the committee and others who have been using the specifications. Some minor changes t h a t relate merely to details of test are not given. One general modification is the use in the nitrate test of 0.1 cc. of indigo carmine
CARBOSDIOXIDE. Dilute 10 cc. of the sample with 10 cc. of water free from carbon dioxide and add 5 cc. of a saturated solution of barium hydroxide. The turbidity should not be greater than is produced when the same quantity of barium hydroxide solution is added to 20 cc. of water (free from carbon dioxide) containing 0.5 mg. of sodium carbonate.
Test
636
Ammonium Nitrate (3) Requirements
FREEACID. The requirement and test for free acid should be
cc. of indigo carmine solution ( 1 in 1000) and then with constant stirring, 10 cc. of sulfuric acid. Heat on the steam bath for 1 hour and stir the precipitate thoroughly several times. The blue color of the clear solution should not be completely discharged.
replaced by the following requirement and test for neutrality. NEUTRALITY.To pass test.
Benzene (10)
Test
NEUTRALITY.Dissolve 5 grams in 50 cc. of freshly boiled and cooled water and add 1 drop of methyl red indicator solution. If a red color is produced not more than 0.10 cc. of 0.1 IT alkali should be required to discharge the red color.
Ammonium Persulfate ( 2 )
Requirement
WATER. To pass test (limit about 0.02 per cent). Test
WATER. Place 10 cc. in a test tube (150 X 16 mm.) loosely stoppered. Pack in cracked ice. KO turbidity should be observed a t the end of 3 minutes.
Requirement
Cadmium Sulfate ( 9 )
INSOLUBLE MATTER. Not more than 0.020 per cent. Test
INSOLUBLE MATTER. The weight of the residue should not exceed 0.0010 gram.
Ammonium Phosphate, Dibasic (3) Requirements
INSOLUBLE MATTER. Kot more than 0.010 per cent. KITRATE(Koa). T o pass test (limit about 0.003 per cent). REACTION TO PHESOLPHTHALEIS. To pass test. IRON (Fe). Not more than 0,001 per cent. Tests
IKSOLUBLE MATTER. The lveight of the residue should not exceed 0.0010 gram. NITRATE, Mix 3 grams with 1 cc. of n-ater and add 1 cc. of sodium chloride solution containing 5 mg. of sodiuni chloride. Add 0.1 cc. of indigo carmine solution (1 in 1000) and 10 cc. of sulfuric acid and stir until all phosphate is in solution. The blue color should not be completely discharged in 5 minutes. REACTION TO PHENOLPHTHALEIN. To a solution of 1 gram in 10 cc. of water add 0.15 cc. of phenolphthalein solution. A perceptible pink color should be produced. IRON.Dissolve 5.0 grams in 100 cc. of water. Dilute 11 cc. of this solution to 40 cc., and add 1 cc. of ammonium hydroxide and 5 cc. of freshly prepared hydrogen sulfide water. Any color produced should not be more than is produced in a standard containing 1 cc. of the solution of the sample, 0.005 mg. of iron, and the same quantities of reagents, in the same volume.
Ammonium Sulfate (2) Test
NITRATE. Dissolve 3 grams in 8 cc. of water and 2 cc. of a sodium chloride solution containing 5 mg. of NaCl per cc. Add 0.10 cc. of indigo carmine solution (1 in 1000) and 10 cc. of sulfuric acid. The blue color should not be completely discharged in 5 minutes.
Ammonium Thiocyanate ( I ) Requirement
IRON (Fe). Kot more than 0.0003 per cent. Test
IRON.Dissolve the residue from the test for nonvolatile mat-
ter using 5 cc. of hydrochloric acid and 5 drops of nitric acid. Heat to boiling, cool, dilute to 25 cc., and add 3 cc. of 30 per cent ammonium thiocyanate solution. Any red color should not be greater than is produced by 0.012 mg. of iron in an equal volume of solution containing the quantities of reagents used in the test.
Arsenic Trioxide ( 4 ) Tests
NONVOLATILE MATTER. Use a platinum dish for heating the sample. IRON.Omit requirement and test for iron.
Requirement
SITRATE. To pass test (limit about 0.003 per cent). Test
SITRATE. Dissolve 1 gram in 8 cc. of warm water and 2 cc. of a sodium chloride solution containing 5 mg. of S a C l per cc. Add 0.10 cc. of indigo carmine solution (1 in 1000) and 10 cc. of sulfuric acid. The blue color should not be completely discharged in 5 minutes.
Calcium Carbonate ( 7 ) Requirement
INSOLUBLE ISHYDROCHLORIC ACIDASD AMMOSIUIIHYDROXIDE PRECIPITATE. S o t more than 0.015 per cent. NITRATE(SO$). To pass test (limit about 0.01 per cent). Tests I K S O L U B L E IK HYDROCHLORIC ACID A S D L ~ M > I O X I U M HYDROXIDE
PRECIPITATE. Use 10 grams for the test. The weight of the
ignited residue should not exceed 0.0015 gram. SITRATE. Dissolye 3 grams in 15 cc. of water, 3 cc. of sodium chloride solution containing 5 mg. S a C l per cc., and 8 cc. of acetic acid. If necessary heat on the steam bath to dissolve the carbonate. Cool and dilute to 30 cc. To 10 cc. add 0.20 cc. of indigo carmine solution (1 in 1000) and 10 cc. of sulfuric acid. Stir thoroughly and allow to stand for 15 minutes. The blue color of the solution should not be completely discharged.
Calcium Carbonate, Low in Alkalies ( 7 ) Requirement
IKSOLCBLE IK HYDROCHLORIC ACID ASD ~ M O S I L X HYDROXIDE S o t more than 0.015 per cent. PRECIPITATE. Test
INSOLUBLE ISHYDROCHLORIC ACIDA N D A m i o x I n I HYDROXIDE Use 10 grams for the test. The weight of the igPRECIPITATE. nited residue should not exceed 0.0015 gram.
Calcium Chloride, Anhydrous ( 3 ) NOTE. The grade of calcium chloride covered by this specification may contain enough boron to make it unsuitable for use in the determination of boron. Requirements
ASSAY. S o t less than 94 per cent as CaC12.
MAGNESIUM as sulfates.
AND
Test
NITRATE. Dissolve 1 gram in 9 cc. of water and 1 cc. of so-
dium chloride solution containing 5 mg. of NaCl per cc. Add 0.20
ALKALISALTS. S o t more than 2.0 per cent Test
hlAGSESImf ASDALKALI SALTS. Dissolve 1 gram and proceed as directed originally.
Carbon Disulfide ( 4 ) FOREIGN SULFIDES. Change this title to “Foreign sulfides and dissolved sulfur”.
Barium Acetate (9) 5
VOI,. 12, NO. 11
INDUSTRIAL AND ENGINEERING CHEMISTRY
Test and requirement remain unchanged. Test
BOILINGRANGE. Note the necessity of keeping the level of the liquid in the flask above the level of the water in the bath during distillation.
NOVEMBER 15, 1940
ANALYTICAL EDITION
637
Carbon Tetrachloride ( 4 ) Test ACID. The water used should be free of carbon dioxide. 0.1 N sodium hydroxide.
Test
PHOSPHATE. Place 10 strips in 10 cc. of water to which have Use
Chromium Trioxide (8) Assay.
been added 1 cc. of nitric acid and 0.5 cc. of ammonium hydroxide. Allow to stand for 10 minutes. Decant the solution, warm, and add 5 cc. of ammonium molybdate solution. Shake a t about 40” C. for 5 minutes. S o precipitate of phosphomolybdate should be produced.
Requirement Kot less than 98 per cent.
Cupric Ammonium Chloride (6) Requirement SITRATE (KO3). To pass test (limit about 0.005 per cent). ‘lest To 2 grams in 10 cc. of water, in a m a l l ErlenSITRATE. meyer flask, add 10 cc. of 20 per cent sodium hydroxide solution. Bring the solution to a boil and boil to remove all ammonia, constantly rotating the flask over a small flame to avoid bumping. Filter and add to the filtrate 0.10 cc. of indigo carmine solution (1 in 1000) and 10 cc. of sulfuric acid. The blue color should not entirely disappear in 5 minutes.
Cupric Sulfate ( 3 ) Test AMMONIEM SULFIDEMETALSOTHERTHSS IRON. Dilute t o 100 cc. the filtrate and washings obtained in the test for ammonium hydroxide precipitate. Exactly neutralize 10 cc. with dilute hydrochloric acid and dilute to 20 cc. Add 2 drops of ammonium hydroxide and 1 cc. of hydrogen sulfide water. The solution should not be darker than a standard prepared in the same m y and containing 0.035 mg. of nickel.
Cuprous Chloride ( 7 ) Requirements ISSOLUBLEIN ACID. Not more than 0.050 per cent. BY HYDROCES SULFIDE. S o t SUBSTASCES XOTPRECIPITATED more than 0.50 per cent as sulfates. Tests ISSOLUBLEIN ACID. The xyeight of the insoluble residue should not exceed 0.0025 gram. SUBSTAXCES NOTPRECIPITATED B Y HYDROGEN SULFIDE. The weight of the ignited residue should not exceed 0.0050 gram.
Lead -4cetate ( 7 ) Requirement
KITRATE(Sos).
To pass test (limit about 0.005 per cent).
Test SITRATE. Dissolve 1 gram in 9 cc. of vater and 1 cc. of sodium chloride solution containing 5 mg. of KaC1 per cc. Add 0.20 cc. of indigo carmine solution (1 in 1000) and 10 cc. of sulfuric acid. Stir thoroughly and alloTy t o stand for 10 minutes. The blue color of the clear solution should not he completely discharged.
Lead Dioxide (3) Requirement CHLORIDE.S o t more than 0.005 per cent. Test CHLORIDE.Dissolve 2 grams in 20 cc. of dilute acetic acid (1 9) to which have been added 2 cc. of hydrogen peroxide (30 per cent). Filter and dilute t o 100 cc. Dilute 10 cc. of this solution to 25 cc. and add 1 cc. of nitric acid and 1 cc. of 0.1 N silver nitrate. Any turbidity should not be greater than is produced by 0.01 mg. of chloride ion in a n equal volume of solution containing the quantities of reagents used in the teat.
+
Litmus Paper ( 9 ) SOTE. When litmus paper is used in a solution the length of the piece should not be more than 0.5 em. Requirement PHOSPHATE. To pass test.
Ilagnesium Sulfate ( 7 ) SoD1m.r (Sa).
Requirement T o pass test (limit about 0.02 per cent Ka2SOa).
Test XITRATE. Dissolve 2 grams in 9 cc. of ivater and 1 cc. of a solution of sodium chloride containing 5 mg. of KaC1 per cc. Add 0.20 cc. of indigo carmine solution (1 in 1000) and 10 cc. of sulfuric acid. The blue color should not be completely discharged in 5 minutes.
Potassium Bisulfate, Fused ( 9 ) Requirement ACIDITY. S o t less than 35.0 per cent nor more than 37.0 per cent as H2SOa.
Potassium Bromate (3) Test
ISSOLUBLE MATTER. The solution should be heated on the steam bath for 1 hour before filtering.
Potassium Carbonate, Anhydrous (2) Requirement INSOLUBLE MATTER. Kot more than 0.010 per cent. Tests
IKSOLUBLE MATTER. Weight of the dried residue should not
exceed 0.0010 gram. A N D CHLORATE.Ignite 1 gram and make compariCHLORIDE son r$-ithturbidity produced by 0.03 mg. of chloride.
Potassium Chloride ( 2 ) Requirements
ISSOLUBLE MATTER. S o t more than 0.005 per cent. CHLORATE AKD KITRATE (c103and Koa). To pass test (limit about 0.001 per cent as c103 or 0.003 per cent as Ko3). This title replaces the title “nitrate” originally printed. Tests
ISSOLUBLE MATTER. The weight of the residue should not exceed 0.0006 gram. CHLORATE AXD SITRATE. Dissolve 1 gram in 10 cc. of water, and add 0.10 cc. of indigo carmine solution (1 in 1000) and 10 cc. of sulfuric acid. The blue color should not be completely discharged in 5 minutes.
Potassium Dichromate ( 1 ) Replace the requirement and test for “insoluble matter” by the requirement and test for “insoluble matter and ammonium hydroxide precipitate” given below. Requirement
INSOLUBLE MATTER A N D Amrosmnr HYDROXIDE PRECIPITATE. S o t more than 0,010 per cent. Tests
INSOLUBLE MATTERASD AMMONIUM HYDROXIDE PRECIPITATE. To a solution of 10 grams of the sample in 100 cc. of water add 1 cc. of ammonium hydroxide and digest for 1 hour on the steam bath. Filter, wash t’horoughly, and ignite. The weight of the ignited precipitate should not exceed 0.0010 gram.
Potassium Ferricyanide (5) Test
ISSOLUBLE MATTER. Dissolve 10 grams in 50 cc. of water a t room temperature, filter promptly through asbestos, n-ash thoroughly, dry at 105’ to 110’ C and weigh. The weight of the residue should not exceed 0.00Ok gram.
VOI,. 12. NO. 11
INDUSTRIAL AKD E N G I X E E R I S G CHE&lISTR\
638
Potassium Iodate (3) Test
The solution for comparison as a KITROGEN CO~IPOUNDS. standard should be made by treatment of a solution of an ammonium salt corresponding to 0.05 mg. of nitrogen.
Sodium Bisulfate Fused (5) Requirement
ACIDITY. S o t more than 42.0 per cent or less than 39.0 p('r rent as HzS04. Test
Potassium Kitrate ( I O )
AmioxImI HYDROXIDE PRECIPITATE. Digest on the stearr bath for 1 hour before filtering.
Test
Sodium Carbonate, Anhydrous (2)
CALCIUM, M A G N E S I U I I , AKD AhIMONICM HYDROXIDE PRECIPITATE. Filter the solution of 10 grams in 75 cc. of water before the addition of reagents.
Potassium Oxalate (II) Test
SULFATE,Ignite 4 grams in a platinum crucible, using a sulfurfree flame. Take up the residue in 25 cc. of water and 5 cc. of bromine water. Heat for 15 minutes on the steam bath, neutralize with hydrochloric acid, add an excess of 1 cc. of N hydrochloric acid, and boil to remove bromine. Dilute to about 100 cc., heat to boiling, add 5 cc. of 10 per cent barium chloride solution and allow to stand for 18 hours. Any precipitate formed should not weigh after ignition over 0.0010 gram more than the precipitate obtained in a blank test made with the same quantities of reagents and including filtration and ignition of the paper.
Potassium Permanganate (2) APPEARANCE. Omit requirement relating to appearance. Tests have shown that there is not necessarily a definite relation between appearance and quality. Requirement
INSOLUBLE MATTER. Iiot more than 0.20 per cent. Test
INSOLUBLE MATTER. Dissolve 2 grams in 150 cc. of warm water a t water-bath temperature. Filter a t once through asbestos in a Gooch crucible, wash thoroughly, dry a t 110" C., and weigh. The weight of the dried residue should not exceed 0.0040 gram.
Potassium Phosphate, Monobasic (4) Test
IROS. Dissolve 5.5 grams in 100 cc. of ivater. Dilute 10 cc. of this solution to 40 cc. and add 2 cc. of ammonium hydroxide and 5 cc. of freshly prepared hydrogen sulfide water. Any color produced should not be more than is produced in a standard containing 1 cc. of the solution of the sample, 0.010 mg. of iron, and the same quantities of reagents, in the same volume.
Sodium Acetate (NaCzH302.3HzO) (3)
Requirements
INSOLUBLE MATTER. Iiot more than 0.010 per cent. AMMONIUMHYDROXIDE PRECIPITATE. Kot more than 0.010 per cent. Use above title in place of "silica and ammonium hydroxide precipitate". Tests
I~VSOLUBLE MBTTER. The weight of the residue should not exceed 0.0010 gram. CHLORIDE.Dissolve 1 gram in 20 cc. of warm water and add 1 cc. of nitric acid and 1 cc. of 0.1 N silver nitrate solution. Any turbidity should not be greater than is produced by 0.05 mg. of chloride ion in an equal volume of solution containing the quantities of reagents used in the test. A~~~rozr~vl\.r HYDROXIDE PRECIPITATE. Dissolve 10 grams in 50 cc. of water, add an excess of sulfuric acid, evaporate, and drive off the fumes of sulfuric acid until the residue is nearly dry. Cool, take up in about 100 cc. of mater, add a few drops of methyl red solution, and add ammonium hydroxide carefully until the solution is just alkaline. Boil, filter, reserving the filtrate for the calcium and magnesium test; wash, rejecting the washings; ignite and weigh the precipitate. The xeight of the ignited precipitate should not exceed 0.0010 gram. For the information of laboratories wishing to determine silica in sodium carbonate the following procedure is suggested: Dissolve 10 grams in 100 cc. of water and acidify with sulfuric acid. Add 50 mg. of iron (added as ferric nitrate), dilute to 300 to 350 cc., make alkaline to litmus with ammonium hydroxide, boil 1 to 2 minutes, filter, and wash well with hot 2 per cent ammonium nitrate solution. Wash the precipitate off the paper into the original beaker, dissolve, and reprecipitate. Filter again on the same paper, wash thoroughly, and ignite a t 900' C. Add 1 to 2 cc. of hydrofluoric acid and 1 drop of sulfuric acid, evaporate, and reignite a t 900" C. Loss in weight is silica. All operations should be done in platinum. CALcru>f AND MAcsEsIm PRECIPITATE. Keutralize the filtrate from the test for ammonium hydroxide precipitate with hydrochloric acid and add an excess of 0.5 cc. of the acid. Filter if necessary. Add 5 cc. of 4 per cent ammonium oxalate solution, 2 cc. of 10 per cent ammonium phosphate solution, and 10 cc. of ammonium hydroxide. Stir \Tell and allow to stand overnight. If any precipitate is formed, filter, wash with w t e r containing 2.5 per cent of ammonia, and dry. Mix the residue with about 0.02 gram of sucrose, ignite, and weigh. The weight of the ignited residue should not exceed 0.0015 gram.
Sodium Chloride ( 5 )
Requirement
Requirement
KEUTRALITY.To pass test (limits approximately 0.02 per cent sodium carbonate or 0.012 per cent acetic acid).
CHLoR.iTE ASD NITRATE(C103 and To pass test (limit about 0,001 per cent as ( 3 1 0 3 or 0.003 per cent as Ko3).
so$).
Test
Test
NEUTRALITY.Dissolve 5 grams in 100 cc. of strictly carbon dioxide-free water. Cool to 10" C. and add 3 drops of phenolphthalein solution. If a pink color is produced, it should be discharged by the addition of 0.1 cc. of 0.1 N hydrochloric acid. If no pink color is produced the addition of 0.1 cc. of 0.1 iV caustic alkali should produce a pink color.
C H L O R ~ ATKED NITRATE. Dissolve 2 grams in 10 cc. of water, and add 0.10 cc. of indigo carmine solution ( 1 in 1000) and 10 cc. of sulfuric acid. The blue color should not be entirely destroyed in 10 minutes.
Sodium Bicarbonate (2) Requirement
INSOLUBLE MATTER. Not more than 0.015 per cent. Tests
weight of the residue should not ISSOLUBLE ~ ~ A T T E R The . exceed 0.0015 gram. Use a 1-gram sample and compare with the turCHLORIDE. bidity produced by 0.03 mg. of chloride,
Sodium Hydroxide ( 1 ) Requirement
ASSAY. Not less than 97 per cent NaOH.
Sodium Nitrite (10) Test
CHLORIDE.To 1 cc. of Solution A add 10 cc. of water and add slowly 1 cc. of glacial acetic acid. Warm gently till no more gas is evolved, cool, and dilute t o 25 cc. Add 1 cc. of nitric acid and 1 cc. of 0.1 N silver nitrate solution. Any turbidity should not be greater than is produced by 0.01 mg. of chloride ion in an equal
NOVEMBER 15, 1940
639
ANALYTICAL EDITION
Xylene (10)
volume of solution containing the quantities of reagents used in the test.
Sodium Oxalate ( I ) Test SULFATE.Ignite 10 grams in a platinum crucible, using an alcohol flame to avoid contamination from a gas flame. Take up the residue in 25 cc. of water and 3 cc. of bromine water. Heat for 15 minutes on the steam bath, neutralize with hydrochloric acid, and add an excess of 1 cc. of dilute acid (1 4). Heat to remove bromine, make to a volume of about 100 cc., heat to boiling, add 5 cc. of 10 per cent barium chloride solution, heat on the steam bath, and allow to stand overnight. If a precipitate is formed the weight of the ignited precipitate should not be more than 0,0005 gram greater than the weight of the ignited precipitate from a blank made Tith the quantities of reagents used in the test.
+
Sodium Thiosulfate (2) ISSOLUBLE
Requiremerit
WATER. To pass test (limit about 0.02 per cent).
Requirement MATTER. Not more than 0.005 per cent. Test
INSOLUBLE MATTER. KOchange except that the n-eight of the residue should not exceed 0.0005 gram.
Toluene (10) Requirement WATER. To pass test (limit about, 0.02 per cent). Test WATER. Place 10 cc. in a test tube (150 X 16 mni.) loosely stoppered. Pack in cracked ice. No turbidity should be observed a t the end of 3 minutes.
Test WATER. Place 10 cc. in a test tube (150 X 16 mm.) loosely stoppered. Pack in cracked ice. S o turbidity should he observed a t the end of 3 minutes.
Zinc Sulfate ( 7 ) Test Dissolve 2 grams in 9 cc. of water and 1 cc. oi 80SITR~TE. d i m chloride solution containing 5 mg. of SaCl per cc. ;Idd 0.20 cc. of indigo carmine solution (1 in 1000) and 10 cc. of sulfuric acid. The blue color should not be completely discharged in 5 minutes.
Specifications Previously Published (1) Committee on Analytical Reagenta, IKD.ESG. CHEY.,17, 7.56 (1925). ( 2 ) Ibid., 18, 636, 759 (1926). (3) Ibid., 19, 645 (1927). (1) Ibid., 19, 1369 (1927). (5) Ibid., 20, 979 (1928). (6) Ibid., Anal. Ed., 1, 171 (1929). (7) Ibid., 2, 351 (1930). (8) Ibid., 3, 221 (1931). (9) Ibid., 4, 154 (1932). (10) Ibid., 4, 347 (1932). (11) Ibid., 5, 289 (1933).
PRESENTED in connection with the report of the C o m m t t e e on Analytical Reagents a t the 97th Meeting of the American Chemiod Society, Baltimore, Md.
Spectrophotometric Determination of Vitamin A Critical Study of Applicability to Fish Liver Oils D. T . EWING AND J. RI. VANDENBELT, Rfichigan State College, East Lansing, >rich., 4. D. EMRZETT
AYD
ihn 0. D. BIRD, Parke, Davis & Company, Detroit, JIich.
I
T IS the general opinion t h a t the determination of vitamin A in fish liver oils and other products by physical methods has shown definite promise of giving satisfactory results. The several factors in the spectrophotometric method have therefore been studied in a n effort to increase our knowledge of its accuracy, in the hope t h a t it may come into more regular application a s a quantitative procedure. The amount of vitamin A in a fish liver oil may be estimated quantitatively in a number of m-ays. The most common are the biological, the colorimetric, and the spectrophotometric methods. T h e historical development of the subject has been covered very thoroughly by Munsell (6). Suffice i t to state t h a t the first biological assays were carried out b y Drummond and Coward ( 2 ) ,the first color reaction using arsenic trichloride b y Rosenheim and Drummond (7), and the color reaction using antimony trichloride by Carr and Price (1). Spectrophotometric measurement in the visible range at 698 m p was made first by Drummond and Morton ( 3 ) . Takahashi et al. (8) first reported on the selective absorption characteristics of vitamin L4i n the ultraviolet, while the absorptive maximum in t h a t region was established a t 328 mp by Morton and Heilbron ( 5 ) . Comparison of the data by these methods has shown, in the hands of various workers, both small and large discrepancies.
Because it is generally recognized t h a t the spectrophotometric method is intrinsically capable of making very accurate determinations with both organic and inorganic substances, the authors have made a careful study of the factors involved with respect t o vitamin A in fish liver oils. This has included the solvent and its action, the effect of variation in cells, the application of Lambert’s and Beer’s laws, the importance of instrument adjustment, the light source, and incidentally the practical limits of a few interfering substances.
Method and Plan Having investigated the above factors, the next step was t o test the precision of the technique. X series of many determinations was made on each of several fish liver oils t o ascertain the spread or variation in the maximum extinction coefficient or E: yalue a t 328 rnF (325 to 328 m p ) on each sample. This was taken as a n indication or index of the reproducibility of the technique.
Fm,
The spectrophotometric setup consisted oi a Bausch & Lonib sector photometer with a quartz optical system and a Bausch & Lomb medium quartz spectrograph. A condensed spark between tungsten steel electrodes supplied the ultraviolet radiation, the energy being generated by a Bausch B: Lomb 450 VA inductance transformer. Eastman S o . 33 photographic plates Fere
