Recommended specifications for analytical ... - ACS Publications

Wichers , A Q. Butler , W D. Collins , F S. Eisenhauer , J F. Flagg , R A. Osborn , Joseph. Rosin , J F. Ross , and John. Wolf. Analytical Chemistry 1...
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Recommended Specifications for Analytical Reagent Chemicals Benzene, Cupric Acetate Normal (Cu(C,H,O,),.H,O), Cupric Nitrate (Cu(N0,),.3H20), Lead Subacetate, Phenolphthalein, Potassium Nitrate, Sodium Fluoride, Sodium Nitrite, Toluene, Xylene W. D. COLLINS,H. V. FARR,J. V. FREEXAN, JOSEPH ROSIN,G. C. SPENCER,E. WICHERS,AND H. H. WILLARD Committee on Analytical Reagents, American Chemical Society

T

HE specifications given below are intended t o serve for reagents to 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 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 to be of the grade recommended below or in previous publications (1-9) from the committee. Directions for the preparation of the ammonium molybdate solution are given under the test for phosphate in ammenium 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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BENZENE

REQUIREMENTS Boiling Range-79.5' to 81' C. Solidification Temperature-Not below 5.2' C. Nonvolatile Matter-Not more than 0.001 per cent. Substances Darkened by Sulfuric Acid-To pass test. Thiophene-To pass test. Sulfur Compounds (S)-Not more than 0.005 per cent.

TESTS Boiling Range-When 100 cc. are subjected to the distillation test described in the U. S. Pharmacopeia, not less than 95 cc. should distil within the range indicated. Solidification Temperature-When tested according to the method described in the U. S. Pharmacopeia, the temperature of solidification should not be below 5.2' C. Nonvolatile Matter-Evaporate 115 cc. on the steam bath and dry at 105' to 110" C. for 30 minutes. The weight of the residue should not exceed 0.0010 gram. Substances Darkened by Sulfuric Acid-Shake 25 cc. with 15 cc. of sulfuric acid for 15 to 20 seconds and allow to separate. Neither the benzene nor the acid should be darkened. Thiophene-Add a few miIligrams of isatin to the mixture of benzene and sulfuric acid from the preceding test, shake well, and allow to stand for 1 hour. The acid layer should not acquire a blue or green color. Sulfur Compounds-Place 30 cc. of approximately 0.5 N alcoholic potassium hydroxide in an Erlenmeyer flask, add 6 cc. of the sample, and boil the mixture ently for 30 minutes under a reflux condenser. Detach the conienser, dilute with 50 cc. of water, and heat on the steam bath until the benzene and alcohol

are evaporated. Add 50 cc. of saturated bromine water and heat for 15 minutes longer. Transfer the solution to a beaker, neutralize with dilute hydrochloric acid (1 4), add an excess of I cc. of the acid, and concentrate to about 50 cc. Filter, if necessary, heat the filtrate to boiling, add 5 cc. of barium chloride solution, heat on the steam bath for 2 hours, and allow to stand overnight. If a precipitate is formed, filter, wash, and ignite. A blank should be run with the quantities of reagents used in the test and including filtration and ignition. The difference between the weights of ignited preci itates for the sample and for the blank should not be more t t a n 0.0020 gram.

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(cu(c~H~o~)~.H~o) REQUIREMENTS Insoluble Matter-Not more than 0.010 per cent. Chloride (C1)-Not more than 0.003 per cent. Sulfate (S04)-Not more than 0.010 per cent. Alkali Salts-Not more than 0.20 per cent. Iron (Fe)-Not more than 0.010 per cent. Ammonium Suljde Metals (other than Fe)-To pass test (limit about 0.01 per cent Ni). CUPRIC ACETATE NORMAL

TESTS Insoluble Matter-Dissolve 10 grams in 150 cc. of water containing 1 cc. of glacial acetic acid 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 0.0010 gram. Chloride-Dissolve 1 gram in 20 cc. of water, 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 0.03 mg. of chloride ion in an equal volume of water containing the quantities of reagents used in the test. Sulfate-To the filtrate from the test for insoluble matter add 5 cc. of glacial acetic acid, heat to boiling, add 5 cc. of 10 per cent barium chloride solution, and allow to stand overnight. Filter, wash, ignite, and weigh. The weight of the barium sulfate should not be more than 0.0025 gram greater than the weight obtained in a blank test with the same quantities of reagents and including filtration. Alkali Salts-Dissolve 4 grams in about 190 cc. of water, add 2 cc. of sulfuric acid, heat to about 70' C., and pass in hydrogen sulfide until the copper is completely precipitated. Dilute to 200 cc. and filter. Evaporate 150 cc. of the filtrate to dryness, ignite, and weigh the residue. The weight - of the residue should not exceed 0.0060 gram. Iron-Warm the residue obtained from the test for alkali salts with 1 cc. of hydrochloric acid and 2 drops of nitric acid, and dilute to 15 cc. with water. Dilute 5 cc. of this solution with 15 cc. of water, and 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 by 0.1 mg. - of iron under the same condizions. Ammonium Sulfide Metals, Other than Iron-To the remaining 10 cc. of the solution of the residue add a slight excess of ammonia. boil for 1 minute, filter, and wash with asmall quantity of hot water. Dilute the filtrate and washings to 25 cc. Exactly neutralize 5 cc. of the filtrate and washings 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 way and containing 0.04 mg. of nickel.

347

ANALYTICAL EDITION

348 CUPRIC NITRATE

(CU(N03)2.3H20)

REQUIREMENTS Insoluble Matter-Not more than 0.010 per cent. Chloride (CI)-Not more than 0.002 per cent. Sulfate (S04)-Not more than 0.01 per cent. Alkali Salts-Not more than 0.05 per cent. Iron (Fe)-Not more than 0.010 per cent. Ammonium Suljide Metals (other than Fe)-To (limit about 0.01 per cent Ni).

pass test

Vol. 4, No. 3

Nitrate-To 10 cc. of Solution A add 2 drops of indi o solution (1 in 1000) and 10 cc. of sulfuric acid. The blue cofor should not disappear in 5 minutes. Substances Not Precipitated by Hydrogen Suljde-Dilute 10 cc. of Solution A with water to 100 cc., pass hydrogen sulfide to precipitate all the lead, and filter. Evaporate 50 cc. of the filtrate to dryness and ignite gently. The weight of the residue should not exceed 0.0015 gram. Copper-To 25 cc. of Solution A, add ammonium hydroxide until barely alkaline, heat on the steam bath for 10 minutes, and add 10 cc. of ammonium hydroxide. No blue color should be observed when the solution is compared with an equal volume of water in a Nessler tube. Iron-Dissolve 2 grams in a few cc. of water, add 2 cc. of sulfuric acid, and heat to fumes of sulfuric acid. Allow t o cool, dilute with water to 30 cc. and filter. To 15 cc. of the filtrate add 2 cc. of hydrochloric aiid and 3 cc. of 10 per cent ammonium thiocyanate solution. Any red color should not be deeper than is produced by 0.05 mg. of iron under the same conditions.

TESTS Insoluble Matter-Dissolve 10 grams in 100 cc. of water containing 0.5 cc. of nitric acid, and heat on the steam bath for 1 hour. Filter through asbestos in a Gooch crucible, wash thoroughly, and dry a t 105" to 110" C. The weight of insoluble residue should not exceed 0.0010 gram. Chloride-Dissolve 1 gram in 20 cc. of water and 1 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 0.02 PHENOLPHTHALEIN mg. of chloride ion in an equal volume of water containing the quantities of reagents used in the test. REQUIREMENTS Sulfate-Dissolve 5 grams in 5 cc. of hot water, add 10 cc. of hydrochloric acid and evaporate to dr ness on the steam bath, Nonvolatile Matter-Not more than 0.050 per cent. redissolve the residue in about 5 cc. ofhot water, add 10 cc. of Insoluble in Alcohol-To pass test. hydrochloric acid and reevaporate to dryness. Dissolve the Solution in Sodium Hydroxide-To pass test. residue in 100 cc. of water, add 1 cc. of hydrochloric acid, and Sensitiveness-To pass test. filter. Heat to boiling, add 5 cc. of 10 per cent barium chloride Melting Point-Not below 258" C. solution, and allow to stand overnight. If a precipitate is formed, filter, wash, and ignite. The weight of the precipitate should TESTS not be more than 0.0013 gram greater than the weight obtained Nonvolatile Matter-Ignite 2 grams and weigh. The residue in a blank test with the same quantities of reagents and including should not weigh more than 0.0010 gram. filtration. Insoluble in Alcohol-Dissolve 1 gram in 15 cc. of alcohol. Alkali Salts-Dissolve 4 grams in about 190 cc. of water, add 2 cc. of sulfuric acid, heat to about 70" C., and pass in hydrogen The solution should be clear, with no insoluble residue. Solution in Sodium Hydroxide-One gram should dissolve sulfide until the co per is completely precipitated. Dilute to 200 cc. and filter. Eva orate 150 cc. of the filtrate to dryness, completely in a mixture of 90 cc. of water and 10 cc. of N sodium and ignite and weigh tge residue. The weight of the residue hydroxide. Sensitiveness-Dissolve 0.1 gram in 10 cc. of neutral alcohol. should not exceed 0.0015 gram. Iron-Warm the residue obtained from the test for alkali salts Add 0.10 cc. of this solution to 200 cc. of carbon dioxide-free with 1 cc. of hydrochloric acid and 2 drops of nitric acid, and water, and add 0.05 cc. of 0.1 N sodium hydroxide. The solution dilute to 15 cc. with water. Dilute 5 cc. of this solution with should show a pink color when compared with an equal volume 15 cc. of water. Add 2 cc. of hydrochloric acid and 3 cc. of 10 of water. Melting Point-Determine by the m e t a d described in the per cent ammonium thiocyanate solution. Any red color should not be deeper than is produced by 0.1 mg. of iron under the U. S. Pharmacopeia. same conditions. Ammonium Sulfide Metals, Other than Iron-To the remaining POTASSIUM NITRATE 10 cc. of the solution of the residue add a slight excess of ammonia, REQUIREMENTS boil for 1 minute, filter, and wash with a small quantity of hot water. Dilute the filtrate and washings to 25 cc. Exactly Insoluble Matter-Not more than 0.005 per cent. neutralize 5 cc. of the filtrate and washings with dilute hydroNeutrality-To pass test. chloric acid and dilute to 20 cc. Add 2 drops of ammonium Chlorine, Total-Not more than 0.002 per cent. hydroxide and 1 cc. of hydrogen sulfide water. The solution Iodate, Nitrite-To pass test (limit about 0.0005 per cent 103; should not be darker than a standard prepared in the same about 0.001 per cent NOa). way and containing 0.04 mg. of nickel. Phosphate (P04)-Not more than 0.0005 per cent. Sulfate (SO4)-Not more than 0.003 per cent. LEAD SUBACETATE Calcium, Magnesium, and Ammonium Hydroxide PrecipitateNot more than 0.010 per cent. REQUIREMENTS Heavy Metals-To pass test (limit about 0.0005 per cent lead). Assay of Lead (Pb)-70 to 73 per cent. Iron (Fe)-Not more than 0.0003 per cent. Insoluble in Acetic Acid-Not more than 0.05 per cent. Sodium (Na)-To pass test (limit about 0.02 per cent). Chloride (C1)-Not more than 0.005 per cent. Nitrate (NOs)-To pass test (limit about 0.003 per cent). TESTS Substances Not Precipitated by Hydrogen Sulfide-Not more Insoluble Matter-Dissolve 10 grams in 50 cc. of water and than 0.30 per cent. allow to stand on the steam bath for 1 hour. Filter through Copper (Cu)-To pass test (limit about 0.005 per cent). asbestos in a Gooch crucible, wash, dry a t 105' to 110" C., Iron (Fe)-Not more than 0.005 per cent. and weigh. The residue should not weigh more than 0.0005 TESTS gram. Neutrality-Dissolve 5 grams in 50 cc. of water free from Assay of Lead-Weigh accurately about 1 gram in a porcelain crucible, add about 0.5 cc. of sulfuric acid, and ignite to drive carbon dioxide, and add 3 drops of phenolphthalein. No pink off the excess of acid. The weight of lead sulfate should corre- color should be produced, but on the addition of 1 drop of 0.1 N sodium hydroxide a pink color should be produced. spond to between 70 and 73 er cent of lead. Chlorine, Total-Ignite 1 gram, a t first gently and then for a Insoluble in Acetic Acid-fhssolve 6 grams in 100 cc. of water If an few minutes a t a low red heat. Cool, dissolve in 20 cc. of water, and 5 cc. of glacial acetic acid, and warm if necessar insoluble residue remains, filter and wash until the wastings are add 1 cc. of nitric acid and 1 cc. of 0.1 N silver nitrate. Any no longer darkened by hydrogen sulfide. Dry a t 105' to 110' C. turbidity should not be greater than is produced by 0.02 mg. of chloride ion under the same conditions. The weight of the residue should not exceed 0.0030 gram. Iodate, Nitrite-Dissolve 1 gram in 10 cc. of water add 2 drops Chloride-Dissolve 1 gram in 10 cc. of water and add 1 cc. of nitric acid and 1 cc. of 0.1 N silver nitrate. Any turbidity of 10 per cent potassium iodide solution, 1 cc. of chloroform, should not be greater than is produced by 0.05 mg. of chloride and 2 cc. of 36 er cent acetic acid. Shake gently for a few ion in an equal volume of solution containing the quantities of minutes. The cfioroform should not acquire a pink or violet color. reagents used in the test. Phosphate-Dissolve 5 grams in 50 cc. of water, add 10 cc. of Solution A-Dissolve 5 grams in 42 cc. of water and 3 cc. of glacial acetic acid, and add 5 cc. of sulfuric acid. After standing nitric acid, and nearly neutralize with ammonium hydroxide. Add 50 cc. of ammonium molybdate solution, shake (at about for about 10 minutes, filter the solution.

July l S , 1932

INDUSTRIAL AND ENGINEERING CHEMISTRY

40" C.) for 5 minutes, and allow to stand one-half hour. Any precipitate formed should not be greater than is produced when a quantity of an alkali phosphate containing 0.025 mg. of phosphate (PO4) is treated according to the above procedure. Sulfate-Dissolve 12 gramstin 20 cc. of water, add 25 cc. of hydrochloric acid, and evaporate to dryness. Treat the residue with 15 cc. of water and 15 cc. of hydrochloric acid, and again evaporate to dr ness. Dissolve the residue in 75 cc. of water, add 1 cc. of N %ydrochloric acid, heat to 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, ignite, and weigh. The weight of the barium sulfate should not be more than 0.0010 gram greater than the weight obtained in a blank test with the same quantity of reagents and including filtration. Calcium, Magnesium, and Ammonium Hydroxide PrecipitateDissolve 10 grams in 75 cc. of water, add 5 cc. of 4 per cent ammonium oxalate solution, 2 cc. of 10 per cent ammonium phosphate solution, and 15 cc. of ammonium hydroxide. Stir well and allow to stand overnight. If any precipitate forms, filter, wash, ignite, and weigh. The weight of the ignited precipitate should not exceed 0.0010 gram. Heavy Metals-Dissolve 2 grams in 20 cc. of water and add 10 cc. of hydrogen sulfide water. No brown color should be produced. Iron-Add ammonium hydroxide to the solution tested for heavy metals until it is alkaline. Any greenish color should not be greater than is produced by 0.006 mg. of iron in an alkaline sulfide solution. Sodium-A 10 per cent solution tested with a platinum Wire in the flame should give no distinct yellow color to the flame. SODIUM FLUORIDE

REQUIREMENTS Insoluble Matter-Not more than 0.050 per cent. Chloride (C1)-Not more than 0.01 per cent. Free Acid (HF)-Not more than 0.2 per cent. Free Alkali (as NazCOs)-Not more than 0.25 per cent. Sodium Fluosilicate (NazSiFa)-Not more than 0.35 per cent. Suljate (S04)-Not more than 0.03 per cent. SulJite (SOa)-Not more than 0.005 per cent. Heavy Metals (as Pb)-Not more than 0.003 per cent. Iron (Fe)-To pass test (limit about 0.003 per cent).

TESTS Insoluble Matter-Dissolve 2 grams in 100 cc. of warm water in a platinum dish and allow to stand on the steam bath for 1 hour. Filter through asbestos in a Gooch crucible, wash thoroughly with hot water, dry at 105' to 110" C., and weigh. The weight should not exceed 0.0010 gram. Chloride-Dissolve 0.3 gram in 20 cc. of water. Add 0.2 gram of boric acid, 1 cc. of nitric acid, and 1 cc. of 0.1 N silver nitrate. Any turbidity produced should not be greater than is produced by 0.03 mg. of chloride ion in an e ual volume of solution containing the quantities of reagents use% in the test. Free Acid-Dissolve 2 grams in 40 cc. of water in a platinum dish, add 10 cc. of a saturated solution of potassium nitrate, and cool the solution to 0' C. Add 3 drops of phenolphthalein indicator. If no pink color is produced, titrate with 0.1 N sodium hydroxide until the pink color persists for 15 seconds while the temperature of the solution is near 0" C. Not more than 2 cc. of 0.1 N sodium hydroxide should be required. Free Alkali-If a ink color is produced on the addition of the phenolphthalein in &e test for free acid, add 0.1 N acid, stirring the liquid only gently, until the pink color is discharged. Not more than 0.5 cc. of the acid should be required. Sodium Fluosilicate-Boil the solution from the preceding test and titrate while hot with 0.1 N alkali until a permanent ink color is obtained. Not more than 1.5 cc. of 0.1 N sodium ydroxide should be required. Sulfate-Evaporate 0.5 gram in a platinum dish four or five times with 10 cc. of hydrochloric acid, evaporating the last time to dryness. Take up the residue in 20 cc. of water and 1 cc. of 0.1 N hydrochloric acid and filter if necessary. Add to the filtrate 2 cc. of 10 per cent barium chloride solution. Any turbidity produced in 10 minutes should not be greater than is produced by 0.15 mg. of SO4in a control made with the quantities of reagents used in the test. Suljte-Dissolve 6 grams in 150 cc. of water, add 2 cc. of hydrochloric acid and a few drops of starch solution, and titrate immediately with 0.1 N iodine. It should require not more than 0.1 cc. to produce a blue color. Heavy Metals-Treat 2 grams in a platinum crucible with 10 cc. of hydrochloric acid and evaporate to dryness. Repeat with another 10 cc. of acid. Warm the residue with a few drops

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349

of hydrochloric acid and dissolve in 40 cc. of hot water. Exactly neutralize 20 cc. with ammonium hydroxide, add 1 cc. of 0.1 N hydrochloric acid, and saturate with hydrogen sulfide. Any color produced should not be greater than is produced by 0.03 mg. of lead in an equal volume of water containing the quantities of reagents used in the test. Iron-To the remaining 20 cc. from the test for heavy metals add 2 cc. of hydrochloric acid, filter if necessary, and add 3 cc. of 10 per cent ammonium thiocyanate solution. Any red color produced should not be more than is produced in a control test made with the same quantities of reagents and containing 0.03 mg. of iron. SODIUM KITRITE

REQUIREMENTS Insoluble Matter-Not more than 0.010 per cent. Assay-Not less than 97 per cent. Chloride (C1)-Not more than 0.01 per cent. Sulfate (SO4)-Not more than 0.020 per cent. Calcium (Ca)-Not more than 0.010 per cent. Heavy Metals (as Pb)-Not more than 0.002 per cent. Iron (Fe)-Not more than 0.001 per cent. Potassium (K)-Not more than 0.01 per cent.

TESTS Insoluble Matter-Dissolve 10 grams in about 100 cc. of hot mater and allow to stand on the steam bath for 1 hour, filter through asbestos in a Gooch crucible, wash thoroughly, dry a t 105' to 110' C., and weigh. The weight of the residue should not exceed 0.0010 gram. Solution A-Dissolve 10 grams in water and make to a volume of 100 cc. Assay-Dilute 10 cc. of Solution A to 100 cc. Mix 300 cc. of water and 5 cc. of sulfuric acid and, while the mixture is still warm, add 0.1 N permanganate solution until a faint pink color is produced which persists for 2 minutes. Add 40 cc. of 0.1 N permanganate solution and mix gently. Run in slowly and with constant agitation 10 cc. of the sodium nitrite solution from a pipet, holding the tip of the pipet well under the surface of the liquid. Add 15 cc. of 0.1 N ferrous ammonium sulfate, and after allowing the solution to stand for 5 minutes, titrate the excess with 0.1 N permanganate. Each cc. of the permanganate consumed corresponds to 0.003450 gram of NaN02. Chloride-To 10 cc. of Solution A add 10 cc. of water, and add slowly 2 cc. of glacial acetic acid. Warm gently until no more gas is evolved, cool, and dilute to 25 cc. Add I cc. of nitric acid and 1 cc. of 0.1 N silver nitrate solution. Any turbidity produced should correspond to not more than 0.1 mg. of chloride. Sulfate-To 10 cc. of Solution A add slowly 2 cc. of hydrochloric acid and evaporate to dryness on the steam bath. Treat the residue with 1 cc. of dilute hydrochloric acid (1 9) and dilute with water to IO cc. Add 1 cc. of 10 per cent barium chloride solution. Any turbidity produced should not be greater than is produced by 0.2 mg. of SO4 under the same conditions. Calcium-To 10 cc. of Solution A add slowly 1 cc. of glacial acetic acid. Heat to expel oxides of nitrogen, cool, dilute to 10 cc., and add 2 cc. of 4 per cent ammonium oxalate solution. Any turbidity produced should not be greater than is produced by 0.1 mg. of calcium under the same conditions. Heavy Metals-To 20 cc. of Solution A add slowly 3 CC. of hydrochloric acid and evaporate to dryness on the steam bath. Treat the residue with 1 cc. of N hydrochloric acid, dilute to 10 cc., and add 2 cc. of hydrogen sulfide water. Any darkening should not be greater than is produced by 0.04 mg. of lead under the same conditions. Iron-To 20 cc. of Solution A add 5 cc. of hydrochloric acid and evaporate on a steam bath almost to dryness. Take up the residue in 2 cc. of hydrochloric acid and 15 cc. of water; filter if necessary, and add to the solution 3 cc. of 10 per cent ammonium thiocyanate solution. Any red color produced should not be greater than in a control test made with the same quantities of the reagent and containing 0.02 mg. of iron. Potassium-Dissolve 2 grams in a mixture of 10 cc. of water and 5 cc. of hydrochloric acid, and evaporate to dryness on the steam bath, finally heating for 15 minutes to about 120" C. Dissolve the salt in 10 cc. of water, and add 10 cc. of sodium cobaltinitrite solution and 7 cc. of alcohol. Any turbidity should not be greater than that produced by a blank containing 10 cc. of water and 10 cc. of cobaltinitrite solution to which have been added 0.2 mg. of potassium and 7 cc. of alcohol. (The sodium cobaltinitrite solution is made by dissolving 25 grams of NaN02 in 50 CG. of water and adding 15 cc. of 6 N HCsHsOa and 2.5 grams of C O ( C ~ H ~ O ~ ) ~or. ~anH equivalent ~O amount of nitrate or chloride. The solution is allowed to stand overnight, filtered, and diluted to 100 cc.)

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350

ANALYTICAL EDITION TOLUENE

REQUIREMENTS Boiling Range-110' to 111' C. Nonvolatile Matter-Not more than 0.001 per cent. Substances Darkened by Sulfuric Acid-To pass test. Sulfur Compounds (as S)-Not more than 0.003 per cent. Water-To pass test.

TESTS Boiling Range-When 100 cc. are distilled by the method described in the U. S. Pharmacopeia, not less than 95 cc. should distil within the temperature range indicated. Nonvolatile Matter-Evaporate 115 cc. on the steam bath and dry a t 105' to 110' C. for 30 minutes. The weight of the residue should not be more than 0.0010 gram. Substances Darkened by Sulfuric Acid-Shake 15 cc. with 5 cc. of sulfuric acid for 15 to 20 seconds and allow to stand 15 minutes. The toluene layer should be colorless and the color of the acid should not exceed that of a mixture of 2 volumes of water and 1 volume of a color standard containing 5 grams of CoClz.6Hz0, 40 grams of FeCls.6Hz0,and 20 cc. of hydrochloric acid in a liter. Sulfur Compounds-Place 30 cc. of approximately 0.5 N alcoholic potassium hydroxide in an Erlenmeyer flask, add 6 cc. of the sample, and boil the mixture gently for 30 minutes under a reflux condenser. Detach the condenser, dilute with 50 cc. of water, and heat on the steam bath until the toluene and alcohol are evaporated. Add 40 cc. of saturated bromine water and heat for 15 minutes longer. Transfer the solution t o a beaker, neutralize with dilute hydrochloric acid (1 4), add an excess of 1 cc. of the acid, and concentrate t o about 50 cc. Filter if necessary, heat the filtrate to boiling, add 5 cc. of barium chloride solution, heat on the steam bath for 2 hours, and allow to stand overnight. If a recipitate is formed, filter, wash, and ignite. A blank shod! be run with the quantities of reagents used in the test and including filtration and ignition. The difference between the weights of ignited precipitates for the samole and for the blank should not be more than 0.0012 gram. Water-cool in crushed ice with the sample protected from moisture in the air. No cloudiness should be observed. S ecial care must be taken in handling the sample before as well as &ring this test to make sure that moisture has not been absorbed from the air.

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of 1 cc. of the acid, and concentrate to about 50 cc. Filter if necessary, heat the filtrate to boiling, add 5 cc. of barium chloride solution, heat on the steam bath for 2 hours, and allow to stand overnight. If a precipitate is formed, filter, wash, and ignite. A blank should be run with the quantities of reagents used in the test and including filtration and ignition. The difference between the weights of ignited precipitates for the sample and for the blank should not be more than 0.0012 gram. Water-cool in crushed ice with the sample protected from moisture in the air. No cloudiness should be observed. S ecial care must be taken in handling the sample before as well as &ring this test to make sure that moisture has not been adsorbed from the air. CORRECTIONS FOR PUBLISHED SPECIFICATIONS

Replace or modify requirements and tests previously printed as indicated below: ACID MOLYBDIC ANHYDRIDE

(4)

REQUIREMENT Sulfate (SOd)-Not more than 0.020 per cent. TEST Sulfate-Boil 1 gram with a mixture of 10 cc. of water and 5 cc. of nitric acid for 5 minutes. Cool thoroughly, dilute to 50 cc., mix well, and filter. Evaporate 10 cc. of the filtrate to dryness on the steam bath, warm the residue with 3 drops of hydrochloric acid and 10 cc. of water, filter if necessary, wash, make the filtrate to 50 cc., and add 1 cc. of 10 per cent barium chloride solution. Any turbidity should not be greater than is produced by 0.04 mg. of sulfate ion in the same volume of solution containing the quantities of acid and barium chloride used in the test. CUPRIC OXIDE, POWDERED AND GRANULAR

(6)

REQUIREMENT Chloride (C1)-Not more than 0.005 per cent. Chloride-Make

TEST comparison with 0.05 mg. of chloride ion. POTASSIUM IODIDE

(3)

TEST Heavy Metals-Third sen,t,ence should begin "Add 1 cc. of 0.1 N hydrochloric acid. . . . Run a blank involving the use of the quantities of sulfuric and hydrochloric acids and ammonium hydroxide used in the test.

XYLENE

REQUIREMENTS Boiling Range-137' to 140' C. Nonvolatile Matter-Not more than 0.002 per cent. Substances Darkened by Sulfuric Acid-To pass test. Sulfur Compounds (as S)-Not more than 0.003 per cent. Water-To pass test.

SODIUM BICARBONATE (8)

TESTS Boiling R a n g e W h e n 100 cc. are distilled by the method described in the U. S. Pharmacopeia, not less than 95 cc. should distil within the temperature range indicated. Nonvolatile Mutter-Evaporate 115 cc. on the steam bath and dry a t 105' to 110' C. for 30 minutes. The weight of the residue should not be more than 0.0020 gram. Substances Darkened by Sulfuric Acid-Shake 15 cc. with 5 cc. of sulfuric acid for 15 to 20 seconds and allow to stand for 15 minutes. The xylene layer should be colorless, and the color of the acid should not exceed that of a mixture of 1 volume of water and 3 volumes of a color standard containing 5 grams of CoC12.6H20,40 grams of FeCls.6H20,and 20 cc. of hydrochloric acid in a liter. Sulfur Compounds-Place 30 cc. of approximately 0.5 N alcoholic potassium hydroxide in an Erlenmeyer flask, add 6 CC. of the sam le, and boil the mixture gently for 30 minutes under a reflux conienser. Detach the condenser, dilute with 50 CC. of water, and heat on the steam bath until the xylene and alcohol are evaporated. Add 50 cc. of saturated bromine water and heat for 15 minutes longer. Transfer the solution to a beaker, neutralize with dilute hydrochloric acid (1 4), add an excess

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Vol. 4, No. 3

REQUIREMENT Calcium, Magnesium, and Ammonium Hydroxide PrecipitateNot more than 0.020 per cent.

TEST Calcium, Magnesium, and Ammonium Hydroxide PrecipitateUse corrected test (8).

SPECIFICATIONS PREVIOUSLY PUBLISHED (1) Committee on Analytical Reagents, IND.ENO.CHEM.,17, 756 (1925). (2) Ibid., 18,636, 759 (1926). (3) Ibid.. 19. 645 (1927). (4j 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). RBCBIVEDMay 16, 1932. Presented in connection with the report of the Committee on Analytical Reagents a t the 83rd Meeting of the American Chemical Society, New Orleans, La., March 28 to April 1, 1932.

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