W . D. Co l l in s, H. V. Fa r r, J . Y. Fr e e m a n, R. A. Os b o r n, Jo s e p h Ro s in, E . Wi c h e r s, a n d H. H. Wil l a r d
Committee on A n alytical Reagents
,
Am erican Chemical SocietyT
HE specifications given below are intended to 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 exami
nation 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 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 to 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 (8). 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 to impurities. Solutions of samples must be filtered for tests in which insoluble matter would interfere.
ACID BENZOIC Re q u i r e m e n t s
Melting Point— 122° to 123° C.
Nonvolatile Mailer— N ot more than 0.010 per cent.
Solution in Ammonium Hydroxide—To pass test.
Chlorine Compounds (as Cl)—To pass test (limit about 0.001 per cent).
Sulfur Compounds (as S)—N ot more than 0.001 per cent.
Heavy Metals—To pass test (limit about 0.0005 per cent lead).
Te s t s
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 at least 122° and the point at which it is all melted should be not over 123° C.
Nonvolatile Matter—Heat 5 grams in a platinum dish at 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 hy
droxide. N o 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 con
taining 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 solu
tion in ammonium hydroxide add 5 cc. of hydrogen sulfide water.
No darkening should be observed.
ACID BORIC Re q u i r e m e n t s
Insoluble in Alcohol—To pass test.
Nonvolatile with Methanol—To pass test (limit about 0.05 per cent).
Chloride (Cl)—N ot more than 0.002 per cent.
Phosphate (P 0 4)—N ot more than 0.001 per cent.
Sulfate (SOt)—N ot more than 0.010 per cent.
Arsenic (As)—N ot 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)—N ot more than 0.001 per cent.
Te s t s
Insoluble in Alcohol—Heat 2 grams with 20 cc. of alcohol under a reflux condenser until the acid is dissolved. The solu
tion, while hot, should be clear with no insoluble residue.
Nonvolatile 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 1 cc. 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 P 0 t.
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 pre
cipitate 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
Heavy Metals—Dissolve 2 grams in 25 cc. of hot water and dilution, with standard sodium hydroxide solution, using phenol- phthalein indicator. 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
Insoluble in Sodium Carbonate Solution—Dissolve 5 grams in 50 cc. of a clear 5 per cent solution of sodium carbonate (an volume containing the same quantities of reagents.
Nitrite—Add 0.5 gram to 50 cc. of water and add 5 cc. of sulfaniiic 1-naphthylamine solution. Heat in a water bath with shaking until the sulfaniiic 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 sulfaniiic 1-naphthylamine is made according to Griess-Ilosvay as follows: Dissolve 0.5 gram of acid sulfaniiic in 150 cc. of 36 per cent acetic acid. Boil 0.1 gram of 1-naphthyl produced by 0.3 mg. of sulfate ion in an equal volume containing the same quantities of reagents.
ACID STJLFUROUS
Assay—Tare a glass-stoppered Erlenmeyer flask containing 50 cc. of 0.1 N iodine. Quickly introduce about 2 cc. of the and pass hydrogen sulfide gas through the solution. No darken
ing should be observed.
Hydrocarbons and Nitrobenzene—To pass test.
Boiling Range—183° to 186° C.
Te s t s
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 hydrochloric acid. The solution while still hot from the mixing should be clear and should remain clear after diluting with 15 cc.
of cold water.
Boiling Range—When 100 cc. are distilled by the method described in the I). S. Pharmacopeia, not less than 95 cc. should distill within the temperature range indicated.
HYDROGEN PEROXIDE Re q u i r e m e n t s
Strength—N ot less than 28 per cent H 50 3.
Nonvolatile Matter—Not more than 0.005 per cent.
July 15, 1933 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y 291 0.1 N potassium permanganate.
Nonvolatile Matter—Evaporate 10 cc. to dryness on the steam chloride ion in an equal volume of solution containing the quan
tities of reagents used in the test. 40 per cent sodium hydroxide, distill the mixture ubtil a volum of 50 cc. is obtained and Nesslerize one-half of the distillate. been added 1 cc. of the acid barium chloride solution.
M ERCURIC BROMIDE Re q u i r e m e n t s
Appearance—White or having at most a v e r y faint tinge. If a mercurous salt is present the product darkens on
exposure to light. „ .
Nonvolatile Matter—N ot more than 0.020 per cent.
Insoluble in Methanol—N ot more than 0.1 per cent.
Chloride (Cl)—To pass test (limit about 0.5 per cent).
Te s t s ,
Nonvolatile Matter—Ignite 2.5 grams with 1 cc. of J iJ fu n c acid. The weight of the residue should not exceed 0.0005 g am.
Insoluble in Methanol—Dissolve 2 grams m 30 cc. of methanol.
Filter on asbestos in a Gooch crucible, and wash with met until the washings remain unaffected by hydrogen sulfide. JJrv at 105° to 110° C. The weight of the residue should not exceed 0<C Wo ride—Weigh accurately about 0.7 gram and moisteni with 5 cc. of water and 1 cc. of 36 per cent acetic acid. Ad gr of coarselv powdered zinc (20 to 30 mesh) and warm g y, shaking frequently until the supernatant liquid becomes cle
(about 10 minutes). Filter, wash, a n d t o t h e c a b in e d filtrate and washings add 2 cc. of ferric nitrate solution (about» pe •/>
2 cc. of nitric acid, and 50 cc. of 0.1 A silver f ’ desiccator containing a good desiccant, such as concentrated sulfuric acid. Accurately weigh about 1 gram of the dried
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
taining the quantities of reagents used in the test.
Sulfur Compounds—Mix 2 grams with 1 grain of sodium car
bonate 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 chloride 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
Neutrality—To pass test (limit of alkalinity equivalent to 0 10 per cent KsCOj, limit of acidity equivalent to 0.05 per cent KHGjOa).
Chloride (Cl)—N ot more than 0.002 per cent.
Sulfate (SO<)—N ot more than 0.010 per cent.
Ammonia (NIL)—N ot 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.
Te s t s boil the solution in a flask of resistant glass for 10 minutes while passing through it a current of air free from carbon dioxide.
Prepare a color standard by adding 0.2 cc. of phenolphthalein solution to 150 cc. of carbon dioxide-free water containing 10 cc.
of 0.1 N sodium hydroxide solution, and diluting 6 cc. of this red liquid to 100 cc. with carbon dioxide-free water. Titrate the potassium oxalate solution with 0.01 N acid or alkali as required to bring its color to match that of the prepared standard.
Not more than 1.4 cc. of the 0.01 N acid or 0.8 cc. of 0.01 N alkali solution should be required.
Chloride—Ignite 2.5 grams to carbonate. Dissolve in 50 cc. quantity of Nessler’s solution used in the test.
Heavy Metals—Ignite 2 grams to carbonate and dissolve the boil until nearly all color is gone. After the solution has cooled to room temperature dilute to 25 cc., add 2 cc. of hydrochloric
nounced yellow color should be produced.
Substance Darkened by Hot Sulfuric Acid—Heat 1 gram in a 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.
Free Alkali—Dissolve 1 gram in 10 cc. of water and add 1.5 cc.
of lead and including evaporation of 5 cc. of hydrochloric acid.
Iron—Decompose 1 gram with 2 cc. of hydrochloric acid and
Replace or modify requirements and tests previously printed as indicated below:
ACID PHOSPHORIC ( 4 ) Te s t
Assay—After last sentence add, “One cubic centimeter of normal alkali solution corresponds to 0.049 gram of H ,P04.”
AMMONIUM SULFATE (S ) R e q u i r e m e n t
Nonvolatile Matter—Not more than 0.015 per cent.
CALCIUM CHLORIDE (CaClj.2HjO) (7)
Re q u i r e m e n t
Insoluble and Ammonium Hydroxide Precipitate—Not more than 0.015 per cent.
July 15, 1933 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
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