Recommended Specifications for Analytical Reagent Chemicals

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Recommended Specifications for Analytical Reagent Chemicals Benzoic, Boric, Formic, Sulfanilic, and Sulfurous Acids, Aniline, Hydrogen Peroxide, Mercuric Bromide, Potassium Biphthalate, Potassium Oxalate, Sodium Sulfite Anhydrous

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W. D. COLLINS,H. V. FARR,J. V. FREEMAN, R. A. OSBORN,JOSEPH ROSIN,E. WICHERS,AND H. H. WILLARD Committee on Analytical Reagents, American Chemical Society

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HE specifications given below are intended to serve for reagents t o be used in careful analytical work.

T h e 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 b y members of the committee as the 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 t o 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 (1-10) 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 t o 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 BENZOIC

REQUIREMENTS Melting Point-122" to 123" C. Nonvolatile Matter-Not more than 0.010 per cent. Solution in Ammonium Hydroxide-To pass test. Chlorine Compounds (as C1)-To pass test (limit about 0.001 per cent). Sulfur Compounds (as S)-Not more than 0.001 per cent. Heavy Metals-To pass test (limit about 0.0005 per cent lead).

TESTS Melting Point-Determine according to the directions of the U. S. Pharmacopeia. When these directions are followed the initial melting point, that at which the material collapses in the tube, should be a t least 122" and the point a t which it is all melted should be not over 123' C. Nonvolatile Matter-Heat 5 grams in a platinum dish a t a temperature sufficient to volatilize the acid slowly but not to char or ignite it. When nearly all of the acid has volatilized add a few drops of sulfuric acid and ignite gently. The weight of the residue should not exceed 0.0005 gram. Solution in Ammonium Hydroxide-Dissolve 2 grams in a mixture of 15 cc. of warm water and 5 cc. of ammonium hydroxide. No visible residue should remain. Chlorine Compounds-Mix 1 gram with 0.5 gram of sodium carbonate and add 10 to 15 cc. of water. Evaporate on the steam bath and ignite until the mass is thoroughly charred, avoiding an unduly high temperature. Extract the fusion with 10 cc. of water and 1.5 cc. of nitric acid. Filter, wash, make to a volume of 25 to 30 cc., and add 1 cc. of 0.1 N silver nitrate. The 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.

Sulfur Compounds-Mix 2 grams with 1.5 grams of sodium carbonate and dissolve in water. Evaporate to dryness and char thoroughly with a flame free from sulfur. Treat with 25 cc. of water, add a few cubic centimeters of saturated bromine water, and heat on the steam bath for 15 minutes. Neutralize with hydrochloric acid, adding a slight excess of the acid, boil gently to expel the bromine, filter, and wash. Add to the filtrate, which should measure about 25 cc., 2 cc. of 10 per cent barium chloride solution. The turbidity should not be greater than is produced by 0.06 mg. of sulfate ion in an equal volume with the quantities of reagents used in the test. Heavy Metals-To the solution prepared for the test for solution in ammonium hydroxide add 5 cc. of hydrogen sulfide water. N o darkening should be observed. ACID BORIC

REQUIREMENTS Insoluble in Alcohol-To pass test. Nonvolatile with Methanol-To pass test (limit about 0.05 per cent). Chloride ((31)-Not more than 0.002 per cent. Phosphate (POJ-Not more than 0.001 per cent. Sulfate (Sod)-Not more than 0.010 per cent. Arsenic (As)-Not more than 0.0005 per cent. Calcium (Ca)-To pass test (limit about 0.005 per cent). Heavy Metals-To pass test (limit about 0.001 per cent as lead). Iron (Fe)-Not more than 0.001 per cent.

TESTS Insoluble in AlcohoZ-Heat 2 grams with 20 cc. of alcohol under a reflux condenser until the acid is dissolved. The solution while hot, should be clear with no insoluble residue. donvolatile with Methanol-Dissolve 2 grams of the powdered acid in 25 cc. of methanol and 5 drops of hydrochloric acid in a platinum dish and evaporate to dryness. Add 15 cc. of methanol and 3 drops of hydrochloric acid and repeat the evaporation. Add 2 to 3 drops of sulfuric acid to the residue and ignite. The weight of the residue should not exceed 0.0010 gram. Chloride-Dissolve 1 gram in 15 cc. of warm water and add 1cc. of nitric acid and 1 cc. of 0.1 N silver nitrate. The turbidity should not be greater than is produced by 0.02 mg. of chloride ion in an equal volume of solution containing the quantities of reagents used in the test. Phosphate-Dissolve 5 grams in 75 cc. of warm water, and add 10 cc. of nitric acid and 8 cc. of ammonium hydroxide. Warm to 60' C., add 50 cc. of ammonium molybdate solution, and shake for 5 minutes. Any precipitate should not be greater than is produced in a solution of equal volume with the same quantities of reagents and 0.05 mg. of PO1. Sulfate-Dissolve 4 grams in 75 cc. of hot water and add 1 cc. of hydrochloric acid. Heat to boiling, add 5 cc. of 10 per cent barium chloride solution, and let stand overnight. Filter, wash and ignite, and weigh. The weight of the ignited precipitate should not be more than 0.0010 gram greater than the weight of the ignited precipitate from a blank made with the quantities of the reagents used in the test, including filtration and ignition of the paper. Arsenic-Dissolve 0.4 gram in 10 cc. of water and apply the modified Gutzeit test as described in the U. S. Pharmacopeia. The stain produced should correspond to not more than 0.002 mg. of arsenic. Calcium-Dissolve 2 grams in 25 cc. of water and add 1 cc. of acetic acid and 5 cc. of 4 per cent ammonium oxalate solution. No turbidity should be observed in 10 minutes.

289

ANALYTICAL EDITION

290

Heavy Metals-Dissolve 2 grams in 25 cc. of hot water and add 1 cc. of N hydrochloric acid. Heat to about 80" C. and add 5 cc. of hydrogen sulfide water. No darkening of the solution should be observed. Iron-Add ammonium hydroxide to the solution tested for heavy metals until it is distinctly alkaline. Any greenish color should not be greater than is produced by 0.02 mg. of iron in an alkaline sulfide solution. ACID FORMIC

REQUIREMENTS Assay-Not less than 87 per cent. Dilution Test-To pass test. Nonvolatile Matter-Not more than 0.002 per cent. Acetic Acid-To pass test (limit about 0.4 per cent). Chloride (C1)-To pass test (limit about 0.001 per cent). Sulfate (S04)-Not more than 0.002 per cent. Sulfite (SOa)-To pass test. Heavy Metals-To pass test (limit about 0.0005 per cent lead; about 0.0005 per cent iron).

Vol. 5 , No. 4

greater than is produced by 0.01 mg. of chloride ion in an equal volume containing the same quantities of reagents. Nitrite-Add 0.5 gram to 50 cc. of water and add 5 cc. of sulfanilic 1-naphthylamine solution. Heat in a water bath with shaking until the sulfanilic acid is in solution. The solution should show no more pink color than a water blank containing 5 cc. of the reagent solution. (The solution of sulfanilic 1-naphthylamine is made according to Griess-Ilosvay as follows: Dissolve 0.5 gram of acid sulfanilic in 150 cc. of 36 per cent acetic acid. Boil 0.1 gram of l-naphthylamine with 20 cc. of water, pour off the colorless liquid from the residue, and add to 150 cc. of 36 per cent acetic acid. Mix the two solutions. If, on standing, the solution develops a pink color it may be discharged with a little zinc dust.) Sulfate-Evaporate*_GO cc. of thafiltrate used in the test for chloride to about 15 cc., cool on ice, filter, and add to the filtrate 0.5 cc. of hydrochloric acid and 1 cc. of 10 per cent barium chloride solution. Any turbidity should not be greater than is produced by 0.3 mg. of sulfate ion in an equal volume containing the same quantities of reagents. ACID SULFUROUS

TESTS Assay-Titrate a weighed portion of the acid, after suitable dilution, with standard sodium hydroxide solution, using phenolphthalein indicator. Dilution Test-Dilute 1 volume of the acid with 3 volumes of water. No turbidity should be observed within 1 hour. Nonvolatile Matter-Evaporate 20 cc. to dryness on the steam bath and dry at 105" to 110" C. The weight of the residue should not exceed 0.0005 gram. Acetic Acid-Dilute 1 cc. to 100 cc. Mix 10 cc. of this solution with 1.5 grams of yellow mercuric oxide. Heat on the steam bath for 20 minutes and then filter. The filtrate should not turn blue litmus paper in 30 seconds. Chloride-Mix 4 cc. of the acid with 5 cc. of water, add 3 CC. of nitric acid and 1 cc. of 0.1 N silver nitrate. Any turbidity should not be greater than is produced by 0.05 mg. of chloride ion in an equal volume containing the quantities of reagents used in the (est. Sulfate-To 4 cc. add 0.01 gram of sodium carbonate and evaporate to dryness. Take up with 5 cc. of water, filter, and make up to a volume of 10 cc. Add 1 cc. of N hydrochloric acid and 1 cc. of 10 per cent barium chloride solution. Any turbidity, after 10 minutes, should not be greater than is produced in an equal volume of distilled water containing 0.01 gram of the same sodium carbonate, 1.2 cc. of N hydrochloric acid, 0.10 mg. of sulfate ion, and the volume of barium chloride used in the test. Sulfite-Dilute 25 cc. of the acid with 25 cc. of water and add 0.1 cc. of 0.1 N iodine solution. The mixture should retain a distinct yellow color. Heavy Metals-Dilute 5 cc. with 10 cc. of water, exactly neutralize with ammonium hydroxide, add 2 cc. of N hydrochloric acid, and pass hydrogen sulfide through the solution. The solution should not be darker than an equal volume of water containing 0.03 mg. of lead and 0.5 cc. of 0.1 N hydrochloric acid through which hydrogen sulfide has been passed. Add to the solution of the sample a slight excess of ammonium hydroxide. The solution should not be darker than an equal volume of water containing 0.03 mg. of iron and 0.5 cc. of 0.1 N hydrochloric acid and the quantities of hydrogen sulfide and ammonium hydroxide used in the test.

REQUIREMENTS Assay-Not less than 6 per cent of SO?. Nonvolatile Matter-Not more than 0.005 per cent. Chloride ((31)-Not more than 0.0005 per cent. Arsenic (As)-Not more than 0.00005 per cent Heavy Metals-To pass test (limit about 0.001 per cent lead). Iron (Fe)-Not more than 0.0005 per cent.

TESTS Assay-Tare a glass-stoppered Erlenmeyer flask containing 50 cc. of 0.1 N iodine. Quickly introduce about 2 cc. of the acid, stopper, and weigh. Titrate the excess iodine with 0.1 N sodium thiosulfate solution. Nonvolatile Matter-Evaporate 10 cc. to dryness, ignite at cherry redness for 5 minutes, cool, and weigh. The weight of the residue should not exceed 0.0005 gram. Chloride-Digest 10 cc. with 2 cc. of nitric acid on the steam bath for 1 hour. Add 1 cc. of 0.1 N silver nitrate. 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 rea ents used in the test. jrsenic-Mix 5 cc. with 0.5 cc. of sulfuric acid and evaporate on the steam bath until free from sulfur dioxide and the volume has been reduced to about 2 cc. Dilute to about 5 cc. and determine the arsenic by the Gutzeit method as described in the U . S. Pharmacopeia. Heavy Metals-Dilute 5 cc. with 10 cc. of water and boil to expel the sulfur dioxide. Neutralize to litmus with ammonium hydroxide, add 2 cc. of 0.1 N hydrochloric acid, dilute to 50 cc., and pass hydrogen sulfide gas through the solution. No darkening should be observed. Iron-Evaporate 2 cc. to dryness. Treat the residue with 0.5 cc. of hydrochloric acid and 3 drops of nitric acid and reevaporate. Take up with 2 cc. of hydrochloric acid, dilute to 20 cc., and add 3 cc. of 30 per cent ammonium thiocyanate solution. Any red color should not be greater than is produced by 0.01 mg. of iron under the same conditions. ANILIiVE

REQUIREMENTS

ACID SULFANILtC

REQUIREMENTS Residue on Ignition-Not more than 0.03 per cent. Insoluble in Sodium Carbonate Solution-Not more than 0.02 per cent. Chloride ((21)-Not more than 0.002 per cent. Nitrite (NOz)-Not more than 0.00005 per cent. Sulfate (SOa)-Not more than 0.01 per cent.

Color-Not more than a pale yellow. Nonvolatile Matter-Not more than 0.005 per cent. Hydrocarbons and Nitrobenzene-To pass test. Boiling Range--183" to 186" c.

TESTS Nonvolatile Matter-Evaporate 10 cc., ignite, and weigh. The weight of the residue should not exceed 0.0005 gram. Hydrocarbons and Nitrobenzene-Mix 5 cc. with 10 cc. of TESTS hydrochloric acid. The solution while still hot from the mixing Residue on Ignition-Ignite 3 grams in a platinum dish. The . should be clear and should remain clear after diluting with 15 CC. of cold water. weight of the residue should not exceed 0.0010 gram. Boiling Range-When 100 cc. are distilled by the method Insoluble in Sodium Carbonate Solution-Dissolve 5 grams in 50 cc. of a clear 5 per cent solution of sodium carbonate (an- described in the U. S. Pharmacopeia, not less than 95 cc. should hydrous), and let stand for 1 hour. If an insoluble residue re- distill within the temperature range indicated. mains, filter, wash with cold water, and dry at 105" C. The HYDROGEK PEROXIDE weight of the residue should not exceed 0.0010 gram. Chloride-Boil 5 grams with 100 cc. of water until dissolved. REQUIREMENTS Cool, dilute to 100 cc., mix well, and filter. To 10 cc. of the Strength-Not less than 28 per cent H202. 2) and 1 cc. of apfiltrate add 1 co. of dilute nitric acid (1 Nonvolatile Mutter-Not more than 0.005 per cent. proximately 0.1 N silver nitrate. Any turbidity should not be

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July 15, 1933

INDUSTRIAL AND ENGINEERING CHEMISTRY

Free Acid-Not more than 0.005 per cent as HzS04. Chloride (C1)-Not more than 0.001 per cent. Nitrogen (N)-Not more than 0.001 per cent. Phosphate (POJ-Not more than 0.0005 per cent. Sulfate (SOJ-Not more than 0.010 per cent.

TESTS Assay-Wei h about 1 cc. in a tared 100-cc. volumetric flask, fill to the marf with water, and mix thoroughly. To 20 cc. of this solution add 20 cc. of sulfuric acid (1 15) and titrate with 0.1 N potassium permanganate. Nonvolatile Matter-Evaporate 10 cc. to dryness on the steam bath, dry at 105' to 110" C., and weigh. The weight of the residue should not exceed 0.0005 gram. Free Acid-Dilute 10 cc. with 90 cc. of water free from carbon dioxide. Add 3 drops of 0.1 per cent methyl red solution and titrate with 0.02 N sodium hydroxide, making a correction for the alkali consumed by a blank containing 90 cc. of water free from carbon dioxide. Chloride-Dilute 3 cc. with 15 cc. of water, add 1 cc. of 0.1 N silver nitrate, and add immediately 1 cc. of nitric acid. Any turbidity should not be greater than is produced by 0.03 mg. of chloride ion in an equal volume of solution containing the quantities of reagents used in the test. Nitrogen-Add a drop of sulfuric acid to 10 cc. and evaporate to about 2 cc. Transfer with the aid of water into a Kjeldahl flask. Add a solution of 0.1 gram of salicylic acid in 10 cc. of sulfuric acid and then about 0.2 gram of sulfur and 5 grams of potassium sulfate. Digest in the usual manner of a Kjeldahl nitrogen determination. Add 70 cc. of water and an excess of 40 per cent sodium hydroxide, distill the mixture until a volume of 50 cc. is obtained and Nesslerize one-half of the distillate. The color should not be greater than is produced by a blank containing a quantity of ammonium salt corresponding- to 0.05 mg. of nitrogen. Phosphate-Evaporate 10 cc. on the steam bath. Take up the residue with 10 cc. of nitric acid. dilute with 50 cc. of water. and nearly neutralize with ammonium hydroxide. Add 50 cc: of ammonium molybdate solution, shake the solution (at about 40' C.) for 5 minutes, and allow to stand 0.5 hour. Any precipitate formed should be less than is produced when a quantity of an alkaline phosphate containing 0.05 mg. of hosphate (Po4) is treated according to the above procedure. $he ammonium molybdate solution is prepared as directed under the test for phosphate in ammonium nitrate ( 3 ) . Sulfate-Dilute 9 cc. to 100. To 5 cc. of the diluted sample add 5 cc. of water and 1 cc. of a solution containing in 100 cc. 10 grams of barium chloride (BaC12.2Hz0) and 5 cc. of hydrochloric acid. The turbidity should not be reater than is produced by 0.05 mg. of sulfate ion in a volume of 10 cc. to which has been added 1 cc. of the acid barium chloride solution.

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MERCURIC BROMIDE

REQUIREMENTS Appearance-White or having at most a very faint yellow tinge. If a mercurous salt is present the product darkens on exposure to light. Nonvolatile Matter-Not more than 0.020 per cent. Insoluble in Methanol-Not more than 0.1 per cent. Chloride (C1)-To pass test (limit about 0.5 per cent).

TESTS Nonvolatile Matter-Ignite 2.5 grams with 1 cc. of sulfuric acid. The weight of the residue should not exceed 0.0005 gram, Insoluble in Methanol-Dissolve 2 grams in 30 cc. of methanol. Filter on asbestos in a Gooch crucible, and wash with methanol until the washings remain unaffected by hydrogen sulfide. Dry at 105" to 110' C. The weight of the residue should not exceed 0.0020 gram. Chloride-Weigh accurately about 0.7 gram and moisten with 5 cc. of water and 1 cc. of 36 per cent acetic acid. Add 5 grams of coarsely powdered zinc (20 to 30 mesh) and warm gently, shaking frequently until the supernatant liquid becomes clear (about 10 minutes). Filter, wash, and to the combined filtrate and washings add 2 cc. of ferric nitrate solution (about 8 per cent), 2 cc. of nitric acid, and 50 cc. of 0.1 N silver nitrate. Filter, wash, and titrate the excess silver nitrate with 0.1 N thiocyanate solution. The volume of silver nitrate consumed should correspond to not more than 55.9 cc. per gram of mercuric bromide. POTASSIUM BIPHTHALATE

REQUIREMENTS Assay-Not less than 99.9 per cent. Insoluble Matter-Not more than 0.005 per cent.

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Loss at 100" C.-Not more than 0.05 per cent. Chlorine Compounds (as C1)-To pass test (limit about 0.003 per cent). Sulfur Compounds (as S)-Not more than 0.002 per cent. Heavy Metals-To pass test (limit about 0.0005 per cent as lead). Iron (Fe)-Not more than 0.001 per cent. TESTS Assay-Dry the sample for 1 hour at 120" C., and cool in a desiccator containing a good desiccant, such as concentrated sulfuric acid. Accurately weigh about 1 gram of the dried sample and transfer to a 306-cc. flask which has been swept free from carbon dioxide. Add 50 cc. of cool water that is free from carbon dioxide, stopper the flask, and shake gently until the sample is dissolved. When the sample is in solution, add 3 drops of a 1 per cent solution of phenolphthalein and titrate with an approximately 0.1 N solution of sodium hydroxide that is free from carbon dioxide, taking precautions to exclude the latter. Determine the quantity of sodium hydroxide required to produce the end point by matching the color in another flask containing the indicator and the same volume of solution free from carbon dioxide. Subtract the amount required from that used in the first titration and calculate the acidity on the basis of the following equation: KHCsH40a

+ NaOH = KNaC&04 + HzO

Each cubic centimeter of 0.1 N sodium hydroxide consumed corresponds to 0.02041 gram of KHC8H404. (From U . S. Bureau of Standards Certificate of Analyses Sample No. 84, Washington, D. C., May 27, 1927.) Insoluble Matter-Dissolve 10 grams in about 100 cc. of hot water and allow to stand on the steam bath for 1 hour. Filter through asbestos in a Gooch crucible, wash thoroughly, dry at 105' to 110' C., and weigh. The weight of the residue should not exceed 0.0005 gram. Loss at 100" C.-Crush quickly a few grams and dry about 2 grams at 100' C. The loss in weieht should not be greater . u than 0.0010 gram. Chlorine Compounds-Mix 0.5 gram with 0.25 gram of sodium carbonate. Moisten the mixture and ignite until thoroughly charred, avoiding an unduly high temperature. Treat with 15 cc. of water and cautiously add 1 cc. of nitric acid. Filter, wash the residue with a few cubic centimeters of hot water, make to volume of 25 to 30 cc., and add 1 cc. of 0.1 N silver nitrate. The turbidity should not be greater than is produced by 0.015 mg. of chloride ion in an equal volume of solution containing the quantities of reagents used in the test. Sulfur Compounds-Mix 2 grams with 1 gram of sodium carbonate and dissolve in water. Evaporate to dryness and char thoroughly with a flame free from sulfur. Treat with 25 cc. of water, add a few cubic centimeters of saturated bromine water, and heat on the steam bath for 15 minutes. Neutralize with hydrochloric acid, adding a slight excess of acid, boil gently to expel the bromine, filter, and wash. Add to the filtrate, which should measure about 25 cc., 2 cc. of 10 per cent barium chloyide solution. Any turbidity should not be greater than is produced by 0.12 mg. of sulfate ion in an equal volume with the quantities of reagents used in the test. Heavy Metals-Dissolve 1.75 grams in 15 cc. of hot water and exactly neutralize the solution with ammonium hydroxide. Dissolve in this same solution 0.25 gram more of potassium biphthalate and add 10 cc. of hydrogen sulfide water. No darkening of the solution should be observed. Iron-To the solution tested for heavy metals add ammonium hydroxide until it is alkaline to litmus. Any greenish color should not be greater than is produced by 0.02 mg. of iron in an alkaline sulfide solution. ~

POTASSIUM OXALATE

REQUIREMENTS Insoluble Matter-Not more than 0.010 per cent. Neutrality-To ass test (limit of alkalinity equivalent to 0 10 er cent KZC& limit of acidity equivalent to 0.05 per cent KHd04) Chloridk (C1)-Not more than 0.002 per cent. Sulfate (Sod)-Not more than 0.010 per cent. Ammonia (NHa)-Not more than 0.002 per cent. Heavy Metals-To pass test (limit about 0.002 per cent lead). Iron (Fe)-To pass test (limit about 0.001 per cent). Sodium (Na)-To pass test (limit about 0.02 per cent). Substances Darkened by Hot Sulfuric Acid-To pass test.

292

ANALYTICAL EDITION

Vol. 5 , No. 4

TESTS Free Alkali-Dissolve 1 gram in 10 cc. of water and add 1.5 cc. Insoluble Matter-Dissolve 10 grams in 100 cc. of water and of 30 per cent hydrogen eroxide which has been previously allow to stand on the steam bath for 1 hour. Filter on asbestos neutralized to methyl r e 8 Shake well and let stand for 5 in a Gooch crucible, wash, dry a t 105" to 110" C., and weigh. minutes. Titrate with 0.1 N acid, using methyl red indicator. Not more than 0.6 cc. of the 0.1 N acid should be required to The residue should not weigh more than 0.0010 gram. Neutrality-Dissolve 2 grams in 150 cc. of water free from neutralize the solution. Chloride-Dissolve 1 gram in 10 cc. of water, add 1.5 cc. of carbon dioxide. Add 0.2 cc. of phenolphthalein solution and boil the solution in a flask of resistant glass for 10 minutes while 30 per cent hydrogen peroxide, and dilute t o 100 cc.; take 10 assing through it a current of air free from carbon dioxide. cc., dilute to 20 cc., and add 1 cc. of nitric acid and 1 cc. of 0.1 N silver'nitrate. Any turbidity should not be greater than grepare a color standard by adding 0.2 cc. of phenolphthalein solution to 150 cc. of carbon dioxide-free water containing 10 cc. is produced by 0.02 mg. of chloride ion in an equal volume of of 0.1 N sodium hydroxide solution, and diluting 6 cc. of this solution containing the same quantities of nitric acid and silver red liquid to 100 CC. with carbon dioxide-free water. Titrate nitrate used in the test. It is not necessary to add hydrogen the potassium oxalate solution with 0.01 N acid or alkali as peroxide to the blank. Arsenic-Dissolve 1 gram in 10 cc. of water, add 1 cc. of required to bring its color to match that of the prepared standard. sulfuric acid, evaporate to about 1 cc. on the steam bath, and Not more than 1.4 cc. of the 0.01 N acid or 0.8 cc. of 0.01 N a ply to the residue the modified Gutzeit test as described in alkali solution should be required. Chloride-Ignite 2.5 grams to carbonate. Dissolve in 50 cc. t f e U . S. Pharmacopeia. Heavy Metals-Dissolve 2 grams in 10 cc. 6f water, add 5 cc. of water, neutralize with nitric acid, and fdter if necessary. Make up to 100 cc. To 10 cc. in a test tube, add 1 cc. of dilute of hydrochloric acid, and evaporate to complete dryness on the nitric acid (1 9) and 1 cc. of 0.1 N silver nitrate solution. steam bath. Take up residue in 1 cc. of 0.1 N hydrochloric Any turbidity should not be greater than is produced by 0.005 acid and 25 cc. of water and pass in hydrogen sulfide. Any mg. of chloride ion in 10 cc. of distilled water to which are added darkening should not be greater than is produced in a control test made with a quantity of lead salt equivalent to 0.04 mg. the quantities of acid and silver nitrate used in the test. SuZ ate-Ignite 4 grams in a platinum crucible, using a sulfur- of lead and including evaporation of 5 cc. of hydrochloric acid. Iron-Decompose 1 gram with 2 cc. of hydrochloric acid and free ame. Dissolve the residue in 50 cc. of water, neutralize with hydrochloric acid, and add an excess of 1 cc. of N hydro- evaporate to dryness. Take up the residue in 2 cc. of water chloric acid. Dilute to about 100 cc., heat to boiling, add 5 CC. followed by 2 cc. of hydrochloric acid and 20 cc. of water, add of 10 per cent barium chloride solution, and allow to stand for 3 drops of bromine water, boil off the bromine, cool, and add 18 hours. Any precipitate formed should not weigh after igni- 3 cc. of 30 per cent ammonium thiocyanate solution. Any red tion over 0.0010 gram more than the precipitate obtained in a color roduced should not be greater than is produced in a blank test made with the same uantities of reagents and in- controy test made with 0.01 mg. of iron. cluding filtration and ignition of &e paper. Ammonia-Dissolve 1 gram in 20 cc. of water, and add 2 CC. CORRECTIONS FOR PUBLISHED SPECIFICATIONS of Nessler's solution. The color -should not be more than is produced by a quantity of ammonium salt corresponding to Replace or modify requirements and tests previously 0.02 mg. of NHa in an equal volume of solution containing the printed as indicated below: quantity of Nessler's solution used in the test. Heavy Metals-Ignite 2 grams to carbonate and dissolve the ACID PHOSPHORIC ( 4 ) residue in 10 cc. of water. Neutralize with hydrochloric acid and add an excess of 1 cc. of 0.1 N hydrochloric acid. Dilute TEST to 25 cc. with water and pass hydrogen sulfide through the Assay-After last sentence add, "One cubic centimetEr of diluted solution. Any brown color should not be darker than normal alkali solution corresponds to 0.049 gram of HaPOa. is produced by 0.04 mg. of lead under the same conditions. Iron-Ignite 3 grams to carbonate and dissolve the residue AMMONIUM SULFATE (8) in 20 cc. of water. Neutralize with hydrochloric acid and add an excess of 1 cc. of strong acid. Add 1 drop of bromine and REQUIREMENT boil until nearly all color is gone. After the solution has cooled Nonvolatile Matter-Not more than 0.015 per cent. to room tem~eraturedilute to 25 cc., add 2 cc. of hydrochlorlc acid, and 3 cc. of 30 er cent ammonium thiocyanate solution. CALCIUM CHLORIDE (CaCl2.2H20)(7) The color should not {e more than is produced in a control test made with 0.03 mg. of iron. REQUIREMENT Sodium-Ignite 1 gram to carbonate in a platinum crucible Insoluble and Ammonium Hydroxide Precipitate-Not more and dissolve the residue in 5 cc. of dilute hydrochloric acid. Test the solution on a platinum wire in the flame. NO pro- than 0.015 per cent. nounced yellow color should be produced. TEST Substance Darkened by Ho! Sulfuric Acid-Heat 1. gram. in a recently ignited test tube with 10 cc. of sulfuric acid until the Assay-Second sentence s k u l d read, "Transfer 25 cc. to a appearance of fumes. The acid should not acquire more than 200-cc. graduated flask. a slight brownish tinge. SODIUM BEMUTHATXI (8)

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SODIUM SULFITE ANHYDROUS

REQUIREMENTS Assay-Not less than 95 per cent NazSOs. Insoluble Matter-Not more than 0.01 per cent. Free Acid-To pass test. Free Alkali-To pass test (limit of alkalinity equivalent to 0.3 er cent NaaCOs). Ciloride (C1)-Not more than 0.02 per cent. Arsenic (As)-Not more than 0.0002 per cent. Heavy Metals-Not more than 0.002 per cent as lead. Iron (Fe)-Not more than 0.001 per cent.

TESTS Assay-Weigh accurately about 0.25 gram and add it to 50 cc. of 0.1 N iodine solution (the sulfite must be added to the iodine solution). After standing 5 minutes add 1 cc. of hydrochloric acid and titrate the excess iodine with 0.1 N thiosulfate. Insoluble 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, dry a t 105' to 110" C., and weigh. The weight of the residue should not exceed 0.0010 gram. Free Acid-Dissolve 1 gram in 10 cc. of water and add 2 drops of phenolphthalein solution. A pink color should be produced.

REQUIREMENT Chloride-Not

more than 0.002 per cent.

TEST Chloride-Make comparison with 0.02 mg. of chloride.

SPECIFICATIONS PREVIOUSLY PUBLISHED (1) Committee on Analytical Reagents, IND.ENQ.CHEM., 17, 756 (1925). (2) Zbid., 18, 636, 759 (1926). (3) Ibfd., 19, 645 (1927). (4) Ibid.. 19. 1369 (1927). (5j a d . , 20, 979 (imj. (6) Zbid., 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). RBCEIVED April 29, 1933. Presented in connection with the report of the Committee on Analytical Reagents at the 86th Meeting of the Ameriosn Chemical Society, Washington, D. C., March 26 to 81, 1933.