I X D U S T R I A L A X D ENGINEERISG CHE.WISTRY
June, 1926
procedure. The ammonium molybdate solution is prepared a s directed under the test for phosphate in acetic anhydride. Suljale-Dissolve 5 grams in 100 cc. of water, a d d 1 CC. of dilute hydrochloric acid (1 volume of strong acid in 4 J , heat to boiling, a d d 5 cc. of barium chloride, and allow to stand overnight. N o precipitate or turbidity should be produced. ' Calcium and Magnesium Precipitale-Warm the residue obtained in the determination of nonvolatile matter with 1 cc. of hydrochloric acid and 3 cc. of water. Add 2 cc. of ammonium hydroxide, filter, and add to the filtrate 2 cc. of 4 per cent ammonium oxalate solution a n d 2 cc. of 10 per cent ammonium phosphate. Allow t o stand overnight. If a n y precipitate is formed, filter, wash with a solution containing 2.5 per cent of ammonia. The weight of the ignited precipitate should not be more than 0.0004 gram. Heavy Melds, Iron-Dissolve 5 grams in 50 cc. of water, pass hydrogen sulfide through the solution, a n d a d d 1 cc. of ammonium hydroxide. h70 brown color should be produced (lead). Any green color should not be greater than is produced b y 0.025 mg. of iron in an equal volume of solution containing the quantities of ammonium hydroxide and sulfide used in the test.
A m m o n i u m Persulfate REQUIREMENTS Assay-Not less than 85 per cent (NH4)EhOs. Insoluble Muller-Not more than 0.040 per cent. Xonvolalile Matter-Not more than 0.25 per cent. Chloride (C1)-Not more than 0.001 per cent. Manganese (Mn)-Not more than 0.0001 per cent. Heacy ddelals-Not more than 0.030 per cent a s oxides.
TESTS Blank tests must be made on water a n d all reagents used in the methods unless the directions provide for elimination of errors due t o impurities. Solutions of the sample must be filtered for tests in which insoluble matter would interfere. Assass-Add 0 . 3 gram t o 25 cc. of a 10 per cent solution of potassium iodide. Then add 10 cc. of 10 per cent sulfuric acid, allow to stand onehalf hour, and titrate the liberated iodine with 0.1 N sodium thiosulfate. Make a blank test with the quantities of reagents used with the sample and apply a correction if necessary. Insoluble Matter-Dissolve 5 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., a n d weigh. The residue should not weigh more than 0.0020 gram. Nonvololile Muller-Gently ignite 2 grams in a weighed dish. The residue should not weigh more than 0.0060 gram. Chloride-Dissolve 2 grams in 10 cc. of water and a d d 0.5 cc. of 0.1 N silver nitrate solution. A n y turbidity produced in one minute should not be greater than t h a t produced b y 0.02 mg. of chIoride ion in the same volume of distilled water slightly acidified with nitric acid and containing 0.5 cc. of 0.1 N silver nitrate. Manganese-To the residue obtained from the volatilization of 9 grams of the sample a d d 10 drops of hydrochloric acid and evaporate to dryness on the water bath. Add 2 cc. of sulfuric acid a n d heat until fumes of sulfur trioxide are evolved. Cool, cautiously dilute with 20 cc. of water in a small flask, add 1.5 cc. of 0.1 N silver nitrate, heat to between 80' and 85' C., immediately add 1 gram of ammonium persulfate, and maintain at this temperature for 1 minute. Cool quickly and if not clear filter through a small pledget of glass wool. If the filtrate is pink, match the color in a blank (omitting hydrochloric acid) b y the addition of dilute standard potassium permanganate solution. The quantity of permanganate required to match the color should correspond to not more than 0.01 mg. of manganese (Mn). Heavy Melds-To the residue obtained in the test for nonvolatile matter a d d 2 cc. of hydrochloric acid and a few drops of nitric acid a n d evaporate t o dryness on the water bath. Take up the residue with a few drops of hydrochloric acid and 10 cc. of water, filter, and wash with a small amount of hot water. Pass hydrogen sulfide through the filtrate a n d render the filtrate slightly alkaline with ammonium hydroxide. Heat on the steam bath to coagulate the sulfides, filter (without washing), dry, ignite, and weigh. The weight should not exceed 0.0006 gram.
A m m o n i u m Sulfate REQUIREMENTS Insoluble Mailer-Not more than 0.005 per cent. Nonvolatile Mallev-Not more than 0.010 per cent. Free Acid-To pass test. Chloride (CI)-Not more than 0.0006 per cent. Xilratc? (NO+-To pass test (limit about 0.001per cent). Phosphate (POd)-Not more than 0.0005 per cent. Arsenic (AsI-Not more than 0.0005 per cent. Heaoy'Melals-To pass test (limit about 0.0005 per cent lead). Iron (Fe)-To pass test (limit about 0.0005 per cent).
639 TESTS
Blank lests must be made on water and all reagents used in the methods unless the directions provide for elimination of errors due to impurities. Solutions of the sample must be filtered for tests in which insoluble matter would interfere. Insoluble Muller-Dissolve 10 grams in 50 cc. of water, 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 0.0006 gram. A-onoolafile Matter-Heat 10 grams gently in a weighed dish till the salt is volatilized, and ignite a t cherry redness for 5 minutes. The weight of the residue should not be more than 0,0010gram. Free Acid-Dissolve 5 grams in 50 cc. of carbon dioxide-free water and add 1 drop of methyl red indicator solution. No red color should be produced. Chloride-Dissolve 2 grams in 20 cc. of water, a d d 1cc. of nitric acid and 0.5 cc. of 0.1 N silver nitrate solution. The turbidity should not be greater than is produced b y 0.01 mg. of chloride ion in a n equal volume of solution with the quantities of reagents used in the test. Nitrale-Dissolve 3 grams in 10 cc. of water a n d add 10 cc. of sulfuric acid. T o the hot solution add about 5 mg. of sodium chloride a n d 1 drop of indigo solution (1 in 1000). The blue color should not be entirely discharged after standing 5 minutes. Phosphate-Dissolve 6 grams in 50 cc. of water, a d d 10 cc. of nitric acid, nearly neutralize with ammonium hydroxide, add 50 cc. of ammonium molybdate solution, shake for 5 minutes at about 40' C., and allow to stand for 1 hour. Any precipitate produced should not be greater than is produced from a quantity of an alkaline phosphate containing 0.025 mg. of Po4 which has been treated like the sample. Arsenic-Test 1 gram b y the modified Gutzeit method. The quantity of arsenic found should not be more than 0.005 mg. Special care in making blank tests is necessary in this determination. Heavy Mefals-Dissolve 2 grams in 50 cc. of water, a d d 0.5 cc. of glacial acetic acid, and pass hydrogen sulfide through the solution. N o brown color should be produced. Iron-Render the solution obtained in t h e heavy metals test alkaline with ammonium hydroxide. If a n y greenish color is produced i t should not be greater than is produced by 0.01 mg. of iron in an equal volume of alkaline sulfide solution.
Amyl Alcohol (Isoamyl Alcohol) REQUIREMENTS Nonvolalile Mailer-Not more than 0.003 per cent. Boiling Range-From 128' t o 132O C. Acids and Esters (as amyl acetate)-Not more than 0.060 per cent. Aldehydes-To pass test. Subslances Darkened by Sulfuric Acid-To pass test.
TESTS Blank tests must be made on water a n d all reagents used in the methodr unless the directions provide for elimination of errors due t o impurities. 25 cc. on the steam bath and dry at Nonvolatile Matter-Evaporate 105' to 110' C. The weight of the residue should not exceed 0.0006 gram. Boiling Range-Follow the directions for this test in the U. S. Pharmacopeia X,using 50 cc. of the sample. Acids and Esters-Dilute 20 cc. with 20 cc. of ethyl alcohol, add 5 cc. of 0.1 N sodium hydroxide solution, and heat gently under a reflux condenser for 10 minutes. Cool,,add 3 drops of phenolphthalein indicator solution, and titrate the excess of sodium hydroxide with 0.1 N hydrochloric acid. N o t more than 0.75 cc. of the 0.1 N sodium hydroxide should have been consumed, correction being made for the amount consumed in a blank test. Aldehydes-Shake 5 cc. with 5 cc. of 30 per cent potassium hydroxide solution for 5 minutes in a glass-stoppered cylinder and allow to separate. N o color should develop in either layer. Substances Darkened by Sulfuric Acid-Agitate 10 cc. with an equal volume of sulfuric acid in a glass-stoppered cylinder for 5 minutes. The liquid should be colorless or have not more than a pale yellow color. (To be continued in 2he next issue)
Report of A. C. S. Committee on Guaranteed Reagents During the year 1925-26 the committee prepared tentative specifications for twenty-three reagents, and has considered thirteen additional specifications, several of which are nearly completed. The recommended specifications' do not appear t o be strikingly different from others t h a t have been published. Careful comparison, however, will show t h a t they are more definite in the description of tests and more accurate as regards the limits represented by the tests. 1
Beginning page 636, this issue.
W. D. COLLINS,Chairman
