Identification—

Absorption characteristics— Dissolve 50 mg in 250 mL of 50 percent alcohol. Dilute 3 mL of this solution with 50 percent alcohol to 200 mL. Determine the absorbance, in a 1-cm cell, with a suitable spectrophotometer. The absorbance maximum is in the range of 530 to 533 nm; the ratio (P 15)/(P + 15) is between 1.10 and 1.32, in which P is the wavelength of maximum absorbance.

Assay— When examined by gas-liquid chromatography, using suitable apparatus and conditions, it shows a purity of not less than 98%.

Congealing temperature 651: between 1.0 and 3.0.

Refractive index 831: between 1.573 and 1.574 at 20.

Melting range 741 : between 213 and 219, but the range between beginning and end of melting does not exceed 1.

Chromatography— Proceed as directed in Limit of hydrazine under Povidone: the chromatogram shows only one spot.

Substances soluble in hydrochloric acid— Digest 10 g with a mixture of 10 mL of hydrochloric acid and 40 mL of water on a steam bath for 4 hours, replacing from time to time the water lost by evaporation. Filter, and to 25 mL of the filtrate add 5 drops of sulfuric acid, evaporate, and ignite to constant weight: the residue weighs not more than 8 mg (0.16%).

Chloride (Reagent test)— Shake 1 g with 20 mL of water for 5 minutes, filter, and add to the filtrate 1 mL of nitric acid and 1 mL of silver nitrate TS: any turbidity produced corresponds to not more than 0.03 mg of Cl (0.003%).

Alkaloids— To 5 g of purified sawdust contained in a flask add 50 mL of a mixture of 2 volumes of ether and 1 volume of chloroform and 10 mL of ammonia TS, and shake frequently for 2 hours. Decant 20 mL of the clear, ether-chloroform liquid, and evaporate to dryness. Dissolve the residue in 2 mL of dilute hydrochloric acid (1 in 12), and divide into two portions. To 1 portion add mercuric-potassium iodide TS, and to the other add iodine TS: no turbidity is produced in either portion.

Assay— Accurately weigh about 100 mg, transfer to a glass-stoppered flask, and dissolve in 50 mL of water. Add 10 mL of potassium iodide solution (3 in 10) and 5 mL of hydrochloric acid, mix, insert the stopper in the flask, and allow to stand for 10 minutes. Dilute with 50 mL of water, add 3 mL of starch TS, and titrate with 0.1 N sodium thiosulfate VS until the color is no longer diminished, then titrate with 0.1 N iodine VS to a blue color. Subtract the volume of 0.1 N iodine solution from the volume of 0.1 N sodium thiosulfate to give the volume of 0.1 N thiosulfate equivalent to selenious acid. Each mL of 0.1 N sodium thiosulfate is equivalent to 3.225 mg of H2SeO3: not less than 93% is found.

Insoluble matter— Dissolve 1 g in 5 mL of water: the solution is clear and complete.

Residue on ignition (Reagent test): not more than 1.0 mg (0.01%), from 10 g.

Selenate and sulfate— Dissolve 500 mg in 10 mL of water, and add 0.1 mL of hydrochloric acid and 1 mL of barium chloride TS: no turbidity or precipitate is formed within 10 minutes.

Residue on ignition (Reagent test)— One g yields not more than 2 mg (0.2%).

Heavy metals— To the Residue on ignition add 3 mL of hydrochloric acid and 2 mL of nitric acid, evaporate on a steam bath to dryness, take up the residue in a mixture of 2 mL of diluted hydrochloric acid and 50 mL of hot water, cool, filter, and wash the filter with sufficient water to make 100 mL of filtrate (Test Solution). To a 30-mL aliquot of the Test Solution add 10 mL of water and 10 mL of hydrogen sulfide TS: the color produced is not darker than that of a Control Solution prepared from 3 mL of Standard Lead Solution (see Heavy Metals 231; 0.03 mg of Pb), 0.2 mL of 1 N hydrochloric acid, 37 mL of water, and 10 mL of hydrogen sulfide TS (0.01%).

Iron 241— To 20 mL of the Test Solution prepared in the test for Heavy metals add 2 mL of hydrochloric acid, and dilute with water to 47 mL: the solution shows not more than 0.01 mg of Fe (0.005%).

Nitrogen—

Sulfur— To 1.0 g in a beaker add, successively, 5 mL of nitric acid, then 10 mL of hydrochloric acid, and evaporate on a steam bath to dryness. Add 10 mL of hydrochloric acid, and slowly evaporate again to dryness. Take up the residue in 30 mL of dilute hydrochloric acid (1 in 30), filter, and wash the filter with water to make about 100 mL of the filtrate. Heat the filtrate to boiling, and add slowly, with stirring, 5 mL of barium chloride TS. Digest on the steam bath for 4 hours. Filter on a fine-porosity filter paper, wash the precipitate until it is free from chloride, ignite, and weigh. The weight of the barium sulfate residue, multiplied by 0.1374, represents sulfur (S). Not more than 0.5 mg of S is found (0.05%).

Assay— Weigh accurately about 750 mg, dissolve in 100 mL of methanol, add crystal violet TS, and titrate with 0.1 N perchloric acid to a blue-green endpoint. Each mL of 0.1 N perchloric acid is equivalent to 19.61 mg of C5H11NO2Se: between 97.0% and 103.0%, calculated on the as-is basis, is found.

Melting range 741: about 260, with decomposition.

Nitrogen content 461— Determine by the Kjeldahl method: between 6.8% and 7.4%, calculated on the as-is basis, is found.

Loss on ignition— Ignite 2 g, accurately weighed, at 950 ± 50 to constant weight: it loses not more than 6.0% of its weight.

Water absorption— Place about 10 g in a tared weighing bottle, and weigh. Then place the bottle, with cover removed, for 24 hours in a closed container in which the atmosphere is maintained at 80% relative humidity by being in equilibrium with sulfuric acid having a specific gravity of 1.19. Weigh again: the increase in weight is not less than 31.0% of the weight of test specimen.

Residue on ignition (Reagent test): not less than 80.0%.

Nonvolatile with hydrofluoric acid— Heat 500 mg with 1 mL of sulfuric acid and 10 mL of hydrofluoric acid in a platinum crucible to dryness, and ignite to constant weight: the weight of the residue does not exceed 1.0 mg (0.2%).

Chloride (Reagent test)— One g shows not more than 0.05 mg of Cl (0.005%).

Sulfate (Reagent test)— Boil 2 g with 20 mL of dilute hydrochloric acid (1 in 40), filter, neutralize the filtrate with ammonia TS, and dilute with water to 20.0 mL. A 10-mL aliquot of the solution shows not more than 0.1 mg of SO4 (0.01%).

Heavy metals (Reagent test)— Boil 2.5 g with 50 mL of dilute hydrochloric acid (1 in 10) for 5 minutes, filter while hot, and evaporate the filtrate on a steam bath to dryness. Take up the residue in 20 mL of dilute hydrochloric acid (1 in 500), digest for 5 minutes, cool, add water to make 100 mL, and filter. To 40 mL of the filtrate add 10 mL of hydrogen sulfide TS: any color produced is not darker than that produced by adding 10 mL of hydrogen sulfide TS to a control containing 0.03 mg of Pb (0.003%).

Iron 241— To 20 mL of the filtrate obtained in the test for Heavy metals add 1 mL of hydrochloric acid, and dilute with water to 47 mL: the solution shows not more than 0.015 mg of Fe (0.003%).

NOTE—A suitable grade is available as “OV-25”.

Assay— Dissolve about 1 g, accurately weighed, in 25 mL of dilute hydrochloric acid (1 in 5). Add 50 mL of a solution of 5 g of cinchonine in dilute hydrochloric acid (1 in 2). Warm on a steam bath for about 30 minutes. Cool, filter through a tared crucible, and ignite at 800 to constant weight. The weight of the residue multiplied by 1.047 is equal to the weight of silicotungstic acid dihydrate in the sample taken. Not less than 98% is found.

Change to read:

Assay— Dissolve about 500 mg, previously dried at 120 for 3 hours and accurately weighed, in a mixture of 20 mL of water and 5 mL of nitric acid. Dilute with 100 mL of water, add 2 mL of ferric ammonium sulfate TS, and titrate with 0.1 N ammonium thiocyanate VS to a permanent reddish-brown color. Each mL of 0.1 N ammonium thiocyanate is equivalent to 11.59 mg of Ag2O: not less than 99.7% of Ag2O is found.

Loss on drying— Dry it at 120 for 3 hours: it loses not more than 0.25% of its weight.

Nitrate— To 500 mg add 30 mg of sodium carbonate and 2 mL of phenoldisulfonic acid TS, mix, and heat on a steam bath for 15 minutes. Cool, cautiously add 20 mL of water, render alkaline with ammonia TS, and dilute with water to 30 mL: any color produced by the test solution is not darker than that produced in a control containing 0.01 mg of NO3 (0.002%).

Substances insoluble in nitric acid— Dissolve 5 g in a mixture of 5 mL of nitric acid and 10 mL of water, dilute with water to about 65 mL, and filter any undissolved residue on a tared filtering crucible (retain the filtrate for the test for Substances not precipitated by hydrochloric acid). Wash the crucible with water until the last washing shows no opalescence with 1 drop of hydrochloric acid, and dry at 105 to constant weight: the residue weighs not more than 1 mg (0.02%).

Substances not precipitated by hydrochloric acid— Dilute the filtrate obtained in the test for Substances insoluble in nitric acid with water to 250 mL, heat to boiling, and add, dropwise, sufficient hydrochloric acid to precipitate all of the silver (about 5 mL), avoiding any great excess. Cool, dilute with water to 300 mL, and allow to stand overnight. Filter, evaporate 200 mL of the filtrate in a suitable tared porcelain dish to dryness, and ignite: the residue weighs not more than 1.7 mg (0.05%).

Alkalinity— Heat 2 g with 40 mL of water on a steam bath for 15 minutes, cool, and dilute with water to 50 mL. Filter, discarding the first 10 mL of the filtrate. To 25 mL of the subsequent filtrate add 2 drops of phenolphthalein TS, and titrate with 0.02 N hydrochloric acid VS to the disappearance of any pink color: not more than 0.20 mL is required (0.016% as NaOH).

Specific rotation 781S: between –33 and –39, determined in a solution containing 0.5 g of test specimen per mL of chloroform.

Water, Method I 921: not more than 6%.

Sensitiveness— Add 3 drops of a solution of it (1 in 100) to 100 mL of water, and add 0.25 mL of 0.02 N sodium hydroxide: a red color is produced. Add 0.25 mL of 0.02 N hydrochloric acid: the original yellow color returns.

Insoluble matter and ammonium hydroxide precipitate— Dissolve 10 g in 100 mL of water, add 10 mL of ammonia TS, and heat on a steam bath for 1 hour. If any precipitate is formed, filter, wash well with water, and ignite: the ignited precipitate weighs not more than 1 mg (0.01%).

Chloride (Reagent test)— One g shows not more than 0.02 mg of Cl (0.002%).

Heavy metals— Dissolve 3 g in 25 mL of water, add 15 mL of 1 N sulfuric acid, then add 10 mL of hydrogen sulfide TS: any brown color developed in 1 minute is not darker than that of a control containing 3 mL of Standard Lead Solution (see 231 ) and 0.5 mL of 1 N sulfuric acid (0.001%).

Nitrate— Dissolve 1 g in 10 mL of water, add 0.1 mL of indigo carmine TS, then add, with stirring, 10 mL of sulfuric acid: the blue color persists for 10 minutes (about 0.005%).

Sulfate (Reagent test, Method II )— Dissolve 10 g in 100 mL of water, add 5 mL of hydrochloric acid, and filter if necessary: the filtrate yields not more than 5 mg of residue (0.02%).

Change to read:

Assay— Transfer about 5.5 g, accurately weighed, to a 500-mL volumetric flask, dissolve in and dilute with water to volume, and mix. Pipet 25 mL of this solution into a suitable container, add 50 mL of water and 5 g of dibasic sodium phosphate, swirl to dissolve, and titrate with 0.1 N iodine VS, adding 3 mL of starch TS as the endpoint is approached. Each mL of 0.1 N iodine is equivalent to 3.746 mg of As. Between 57.0% and 60.5% is found (equivalent to 98.8% to 104.9% of NaAsO2).

Chloride (Reagent test)— One g shows not more than 0.10 mg of Cl (0.01%).

Heavy metals— Dissolve 200 mg in 8 mL of dilute hydrochloric acid (3 in 8), and evaporate on a steam bath to dryness. Dissolve the residue in 5 mL of dilute hydrochloric acid (2 in 5), and again evaporate to dryness. Dissolve the residue in 10 mL of water, and add 2 mL of diluted acetic acid and 10 mL of hydrogen sulfide TS. Any brown color produced is not darker than that of a control containing 0.01 mg of added Pb (0.005%).

Iron— Dissolve 1 g in 20 mL of dilute hydrochloric acid (1 in 5), and add, dropwise, a slight excess of bromine TS. Boil the solution to remove the excess bromine, cool, dilute with water to 40 mL, and add 10 mL of ammonium thiocyanate solution (3 in 10). Any red color produced is not darker than that of a control containing 0.02 mg of added Fe (0.02%).

Sulfide— Dissolve 1 g in 20 mL of water, and add 5 drops of lead acetate TS: no brown color is produced (about 0.0005%).

Sulfate (Reagent test, Method II)— Dissolve 5 g in 100 mL of water, add methyl orange TS, neutralize with 1 N hydrochloric acid, add 3 mL of the acid in excess, and filter: the filtrate yields not more than 3 mg of residue (0.02%).

Assay— [Caution—Sodium azide is a potent poison. Its conjugate acid HN3 is more toxic than hydrogen cyanide and is readily liberated from neutral aqueous solutions. Contact of NaH3 or hydrazoic(HN3) with certain metals may produce explosive salts. Work in a well-ventilated hood, and handle the sample with care. ] Dissolve about 100 mg, accurately weighed, in 50 mL of water, and add 3 drops of phenolphthalein. Adjust the pH, if necessary, to 7.0, and add 35.0 mL of 0.1 N perchloric acid. Pipet, while stirring, 2.5 mL of 1.0 M sodium nitrite into the solution, and stir for 15 seconds. Titrate rapidly to the phenolphthalein endpoint with 0.1 N sodium hydroxide. The endpoint should be reached in less than 4 minutes after addition of perchloric acid because HN3 is readily volatile. Calculate the percentage of azide by the formula: where Np is the normality of perchloric acid solution; Vp is the volume of perchloric acid, in mL, taken; Ns is the normality of sodium hydroxide solution; Vs is the volume, in mL, of sodium hydroxide taken; 65.01 is the molecular weight of sodium azide; and C is the weight, in mg, of sodium azide. Not less than 98.5% of NaN3 is found.

Activity— Place 20 mL of dry toluene in a titration flask equipped with a magnetic stirring bar and a stopper having a hole through which the delivery tip of a weight buret may be inserted. Add a quantity of sodium biphenyl sufficient to produce a blue color in the mixture, and titrate with amyl alcohol, contained in a weight buret, to the disappearance of the blue color. (Disregard the amounts of sodium biphenyl and amyl alcohol used in this adjustment.) Weigh accurately the weight buret containing the amyl alcohol. Transfer the contents of a vial of well-mixed test specimen to the titration flask, and titrate quickly with the amyl alcohol to the disappearance of the blue color. Weigh the buret to determine the weight of amyl alcohol consumed, and calculate the activity, in mEq per vial, by the formula: in which W is the weight of amyl alcohol consumed. Not less than 10% activity is found.

Iodine content— Add 10 mL to 5 mL of toluene contained in a 125-mL separator fitted with a suitable inert plastic stopcock, and shake vigorously for 2 minutes. Extract gently with three 10-mL portions of dilute phosphoric acid (1 in 3), combining the lower phases in a 125-mL iodine flask. Add sodium hypochlorite TS, dropwise, to the combined extracts until the solution turns brown, then add 0.5 mL in excess. Shake intermittently for 3 minutes, add 5 mL of freshly prepared, saturated phenol solution, mix, and allow to stand for 1 minute, accurately timed. Add 1 g of potassium iodide, shake for 30 seconds, add 3 mL of starch TS, and titrate with 0.1 N sodium thiosulfate VS: not more than 0.1 mL of 0.1 N sodium thiosulfate is consumed.

Assay— Dissolve about 500 mg, accurately weighed, in 30 mL of water, add phenolphthalein TS, and titrate with 0.1 N sodium hydroxide VS: each mL of 0.1 N sodium hydroxide is equivalent to 19.01 mg of NaHC4H4O6·H2O. Between 99% and 100.5% is found.

Insoluble matter (Reagent test): not more than 1 mg, from 10 g (0.01%).

Chloride (Reagent test)— One g shows not more than 0.2 mg of Cl (0.02%).

Heavy metals (Reagent test)— Dissolve 4 g in 25 mL of water, add 2 drops of phenolphthalein TS, and then add ammonia TS, dropwise, until the solution is slightly pink. Add 4 mL of 1 N hydrochloric acid, dilute with water to 40 mL, and add 10 mL of hydrogen sulfide TS: any brown color produced is not darker than that of a control containing 0.04 mg of added Pb (0.001%).

Sulfate (Reagent test, Method I )— One g shows not more than 0.2 mg of SO4 (0.02%).

Assay—

Change to read:

Assay— Accurately weigh about 300 mg, and dissolve in 10 mL of water contained in a 500-mL flask. Add 3 g of potassium iodide and 10 mL of diluted sulfuric acid, and dilute with 350 mL of oxygen-free and carbon dioxide-free water. Titrate the liberated iodine with 0.1 N sodium thiosulfate VS, adding 3 mL of starch TS as the endpoint is approached. Each mL of 0.1 N sodium thiosulfate consumed is equivalent to 7.802 mg of Na2CrO4·4H2O. Not less than 99% is found.

Insoluble matter (Reagent test): not more than 1 mg, from 20 g dissolved in 150 mL of water (0.005%).

Aluminum— Dissolve 20 g in 140 mL of water, filter, and add 5 mL of glacial acetic acid to the filtrate. Add stronger ammonia water until alkaline, and digest for 2 hours on a steam bath. Filter through hardened filter paper, wash thoroughly, ignite, and weigh: the residue weighs not more than 0.8 mg (0.002%).

Calcium— Determine as directed in the test for calcium for ACS reagent grade Potassium Chromate (0.005%).

Chloride— Determine as directed in the test for chloride for ACS reagent grade Potassium Chromate (about 0.005%).

Sulfate— Determine as directed in the test for sulfate for ACS reagent grade Potassium Dichromate, but add 4.5 mL of hydrochloric acid to the water used to dissolve the test specimen: the residue weighs not more than 2.4 mg (0.01%).

Assay— Dissolve 2 g, accurately weighed, in 400 mL of water, add 10 mL of sulfuric acid, and titrate with 0.1 N potassium permanganate VS. Each mL of 0.1 N potassium permanganate is equivalent to 48.41 mg of Na4Fe(CN)6·10H2O. Not less than 98% is found.

Insoluble matter (Reagent test): not more than 1 mg, from 10 g (0.01%).

Chloride (Reagent test)— Dissolve 1 g in 75 mL of water, add a solution prepared by dissolving 1.2 g of cupric sulfate in 25 mL of water, mix, and allow to stand for 15 minutes. To 20 mL of the decanted, clear liquid add 2 mL of nitric acid and 1 mL of silver nitrate TS: any turbidity produced does not exceed that of a control containing 0.02 mg of Cl, 2 mL of nitric acid, 1 mL of silver nitrate TS, and sufficient cupric sulfate to match the color of the test solution.

Sulfate— Dissolve 5 g in 100 mL of water without heating, filter, and to the filtrate add 0.25 mL of glacial acetic acid and 5 mL of barium chloride TS: no turbidity is produced in 10 minutes (about 0.01% as SO4).

Loss on drying 731— Dry it at 120 to constant weight: it loses not more than 7.0% of its weight.

Change to read:

Specific rotation 781: between +28 and +31, calculated on the dried basis (it is rendered anhydrous by drying at 100 for 2 hours), determined at 20 in a solution containing 10 mg per mL.

Nitrogen, Method I 461: between 2.6% and 3.2% of N is found, calculated on the dried basis.

Add the following:

Melting point 741: about 315.

Assay— Accurately weigh about 1 g, dissolve it in a mixture of 10 mL of formaldehyde TS and 10 mL of water contained in a small glass-stoppered flask, and allow to stand for 30 minutes with frequent agitation. Transfer the solution to a 250-mL volumetric flask, add 150 mL of water and 3 drops of methyl orange TS, and then add, dropwise, 1 N sulfuric acid to a slightly acid reaction. Dilute with water to 250 mL, and mix. To 50.0 mL of the dilution add 2 drops of phenolphthalein TS and just sufficient 0.1 N sodium hydroxide to produce a slight, pink color, then titrate with 0.1 N iodine, adding 3 mL of starch TS as the indicator. Then discharge the blue color of the solution with 1 drop of 0.1 N sodium thiosulfate, and titrate with 0.1 N sodium hydroxide VS to a pink color: each mL of 0.1 N sodium hydroxide is equivalent to 3.482 mg of Na2S2O4. Not less than 88% is found.

Sulfide— Add sodium hydroxide solution (1 in 10) to lead acetate TS until the precipitate dissolves. Add 5 drops of this solution to a solution of 1 g of the sodium hydrosulfite in 10 mL of water: no immediate darkening is observed.

Heavy metals— Dissolve 1 g in 10 mL of water, add 10 mL of hydrochloric acid, and evaporate on a steam bath to dryness. Dissolve the residue in 20 mL of water and 0.5 mL of diluted hydrochloric acid, filter, and add to the filtrate 10 mL of hydrogen sulfide TS: no darkening is produced. Render the solution alkaline with ammonia TS: a slight, greenish color may be produced, but not a dark or white precipitate.

Suitability for riboflavin assay— To each of 2 or more tubes add 10 mL of water and 1.0 mL of a standard riboflavin solution containing 20 µg of riboflavin in each mL, and mix. To each tube add 1.0 mL of glacial acetic acid, mix, add with mixing, 0.5 mL of potassium permanganate solution (1 in 25), and allow to stand for 2 minutes. Then to each tube add, with mixing, 0.5 mL of hydrogen peroxide TS: the permanganate color is destroyed within 10 seconds. Shake the tubes vigorously until excess oxygen is expelled. If gas bubbles remain on the sides of tubes after foaming has ceased, remove the bubbles by tipping the tubes so that the solution flows slowly from end to end. In a suitable fluorometer, measure the fluorescence of the solution. Then add, with mixing, 8.0 mg of sodium hydrosulfite: the riboflavin is completely reduced in not more than 5 seconds.

Assay— Transfer about 3 mL to a tared, glass-stoppered iodine flask, and weigh accurately. Add 50 mL of water, 2 g of potassium iodide, and 10 mL of acetic acid, insert the stopper in the flask, and allow to stand in the dark for 10 minutes. Remove the stopper, rinse the walls of the flask with a few mL of water, and titrate the liberated iodine with 0.1 N sodium thiosulfate VS, adding 3 mL of starch TS as the endpoint is neared. Each mL of 0.1 N sodium thiosulfate consumed is equivalent to 3.723 mg of NaOCl: not less than 5.25% is found. If it is desired to calculate the percentage of available chlorine, note that each mL of 0.1 N sodium thiosulfate consumed is equivalent to 3.545 mg of available chlorine.

Calcium— Transfer 10.0 g to a 150-mL beaker, dissolve in 10 mL of water, and add 5 mL of hydrochloric acid and 2 g of potassium iodide. Heat the mixture for 5 minutes, cool, and add 2 mL of 30 percent hydrogen peroxide. Evaporate to dryness, cool, and add 2 mL of hydrochloric acid and 2 mL of 30 percent hydrogen peroxide. Rinse the inner walls of the beaker with a few mL of water, and evaporate to dryness. Take up the residue in 20 mL of water, and filter if necessary. To the filtrate add ammonium hydroxide until the solution is just alkaline, then add 4 drops of ammonium hydroxide and 5 mL of ammonium oxalate TS: any turbidity produced within 15 minutes does not exceed that in a blank containing 0.1 mg of added Ca carried through the entire procedure (0.001%).

Phosphate (Reagent test)— Transfer 2 g to a beaker, and add 5 mL of hydrochloric acid and 2 g of potassium iodide. Heat the solution for 5 minutes, and cool. Add 2 mL of 30 percent hydrogen peroxide, and evaporate the solution to dryness. Rinse the walls of the beaker with a few mL of water, and add 2 mL of hydrochloric acid and 2 mL of 30 percent hydrogen peroxide. Evaporate again to dryness: the residue shows not more than 0.01 mg of PO4 (5 ppm).

Assay— Transfer about 220 mg to a tared, glass-stoppered flask, and weigh accurately. Dissolve the test specimen in about 10 mL of methanol, then add 100 mL of water slowly, with stirring. Add phenolphthalein TS, and titrate with 0.1 N hydrochloric acid VS to a colorless endpoint: each mL of 0.1 N hydrochloric acid VS is equivalent to 5.402 mg of CH3ONa. Not less than 98.0% is found.

Solubility— Dissolve 500 mg in 50 mL of water, and allow to stand for 1 hour: the solution is clear and free from foreign matter.

Sensitivity—

Solubility— One g, dissolved in 25 mL of water, yields a clear and complete solution.

Water, Method I 921 : not more than 2.0%.

Assay— Transfer about 300 mg, accurately weighed, to a high-form titration beaker, add 150 mL of glacial acetic acid, and stir until dissolved. Titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically, using a glass electrode and a calomel electrode modified to use 0.1 N tetramethylammonium chloride in methanol as the electrolyte. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 11.00 mg of CH3COCO2Na: not less than 98.0% is found.

Solubility— Dissolve 1.5 g in 25 mL of water: the solution is clear and complete.

Free acid— Dissolve 10 g in 150 mL of water, and titrate with 0.5 N sodium hydroxide VS, determining the endpoint potentiometrically: not more than 2.8 mL of 0.5 N sodium hydroxide is consumed (about 1% as C3H4O3).

Nitrate— Dissolve 100 mg in 5 mL of water, and superimpose the solution upon 5 mL of sulfuric acid: no brownish-red color appears at the junction of the two liquids.

Assay— Accurately weigh about 180 mg, previously dried at 120 to constant weight, and dissolve it in 50 mL of water in a glass-stoppered flask. Add, successively, 3 g of potassium iodide and then 5 mL of hydrochloric acid, insert the stopper, and allow to stand for 10 minutes. Add 50 mL of water, 50.0 mL of 0.1 N sodium thiosulfate VS, and 3 mL of starch TS, and immediately titrate with 0.1 N iodine VS to a blue color. Perform a blank determination. The difference in volumes of 0.1 N iodine is equivalent to 4.323 mg of Na2SeO3. Between 98% and 101% is found.

Solubility— One g in 10 mL of water shows not more than a faint haze.

Carbonate— To 500 mg add 1 mL of water and 2 mL of diluted hydrochloric acid: no effervescence is produced.

Chloride (Reagent test)— A 500-mg portion shows not more than 0.05 mg of Cl (0.01%).

Nitrate (Reagent test)— A 200-mg portion dissolved in 3 mL of water shows not more than 0.02 mg of NO3 (0.01%).

Selenate and sulfate (as SO4)— To 500 mg in a small evaporating dish add 20 mg of sodium carbonate and 10 mL of hydrochloric acid. Slowly evaporate the solution on a steam bath under a hood to dryness. Wash the sides of the dish with 5 mL of hydrochloric acid, and again evaporate to dryness. Dissolve the residue in a mixture of 15 mL of hot water and 1 mL of hydrochloric acid. Proceed as directed under Sulfate in Reagents (Reagent test, Method I), beginning with “Filter the solution.” The test specimen shows no more turbidity than that produced by 0.15 mg of SO4 (0.03%).

Suitability for alkaloid assays— Transfer about 10 mg of atropine, accurately weighed, to a 25-mL volumetric flask, dissolve in alcohol, and dilute with alcohol to volume. Pipet 3 mL of the solution into each of two 60-mL separators, and add to each 10 mL of water, 1 mL of 1 N sodium hydroxide, and 10 mL of chloroform. Shake thoroughly, and allow the layers to separate. Filter the organic phase from one separator through phase-separating paper, previously washed with 5 mL of chloroform, supported in a funnel, and collect the filtrate in a suitable container. Add 10 mL of chloroform to the separator, shake thoroughly, and filter the organic layer through the same phase-separating paper, collecting and combining the filtrates in the same container. Designate the combined filtrates as Solution A. Filter the organic phase from the second separator through 30 g of the Anhydrous Sodium Sulfate, supported on a pledget of glass wool in a small funnel, and previously washed with chloroform, and collect the filtrate in a suitable container. Add 10 mL of chloroform to the separator, shake thoroughly, and filter the organic layer through the same portion of anhydrous sodium sulfate, collecting and combining the two filtrates in the same container. Designate the combined filtrates as Solution B. Evaporate the two solutions in vacuum to a volume of about 1 mL. Inject an accurately measured volume of Solution A into a suitable gas chromatography, and record the peak height. Repeat the determination with a second accurately measured volume of Solution A, record the peak height, and obtain the average of the two results. In a similar manner, determine the peak height of two portions of Solution B, and obtain the average of the results. The average value obtained for Solution B is within 5.0% of the value obtained for Solution A.

Assay— Accurately weigh about 250 mg, and dissolve in 50 mL of oxygen-free water. Add 5 mL of diluted hydrochloric acid, boil for 2 minutes, cool, and titrate the solution with 0.1 N iodine VS, adding 3 mL of starch TS toward the end: each mL of 0.1 N iodine is equivalent to 11.41 mg of HSCH2COONa. Not less than 75% is found.

Insoluble matter— A solution of 1 g in 10 mL of water is clear, and practically complete.

Sulfide— Dissolve 500 mg in 10 mL of water in a small flask, add 2 mL of hydrochloric acid, then place a strip of filter paper, moistened with lead acetate TS, over the mouth of the flask, and bring the solution to a boil: the lead acetate paper is not darkened.

TEST SOLUTION FOR DETERMINATION OF PH AND SENSITIVITY— Stir 2.0 g in 10 mL of water, add boiling water to make 100 mL, and boil for 2 minutes. The hot solution is almost clear. On cooling, the solution may become opalescent or turbid, but does not gel. Use it as the Test solution.

Absorbance— Prepare a pH 5.3 buffer solution by dissolving 43.5 g of sodium acetate (trihydrate) and 4.5 mL of glacial acetic acid in water, transferring the resultant solution to a 250-mL volumetric flask, adding water to volume, and mixing.

Reducing substances— Shake 10.0 g with 100 mL of water for 15 minutes, and allow to settle for about 12 hours. Filter a portion of the supernatant through fine sintered glass. To 50 mL of the filtrate add 50 mL of alkaline cupric tartrate TS, and boil for 1 to 2 minutes. Filter the resulting cuprous oxide, wash it with hot water and then with alcohol, and dry it at 105 for 2 hours: not more than 47 mg is found, corresponding to 0.7% of reducing sugars as maltose.

Loss on drying 731— Dry it at 105 for 2 hours: it loses not more than 10% of its weight.

Residue on ignition 281: not more than 0.5%.

Congealing temperature 651 : between 67 and 69.

Acid value 401 : between 196 and 199.

Iodine value 401 : not more than 1.

Saponification value 401 : between 197 and 200.

Palmitic acid— Determine as directed in the Assay under Stearic Acid (NF monograph): not more than 5.0% is found.

Melting range 741 : between 56 and 58.

Other requirements— It conforms to the tests for Acid value, Iodine value, and Hydroxyl value under Stearyl Alcohol (NF monograph).

Assay— Ignite about 3 g, accurately weighed, in a platinum crucible, protecting from sulfur in the flame. Cool, transfer the crucible with the residue to a beaker, and add 50 mL of water and 40.0 mL of 1 N hydrochloric acid VS. Boil gently for 30 minutes or longer, if necessary, filter, wash with hot water until the washings are neutral, add methyl red TS, and titrate the excess acid with 1 N sodium hydroxide VS. Each mL of 1 N hydrochloric acid is equivalent to 107.4 mg of Sr(CH3COO)2·½H2O: not less than 99% is found.

Insoluble matter (Reagent test): not more than 2 mg, from 10 g (0.02%).

Free alkali or free acid— Dissolve 3 g in 30 mL of water, and add 3 drops of phenolphthalein TS: no pink color is produced. Titrate with 0.1 N sodium hydroxide VS to a pink color: not more than 0.30 mL of the 0.1 N sodium hydroxide is required.

Barium— Dissolve 1 g in 10 mL of water, and add 1 drop of glacial acetic acid and 5 drops of potassium dichromate solution (1 in 10): no turbidity is produced within 2 minutes (about 0.02%).

Calcium— Ignite 1 g until completely carbonized. Warm the residue with a mixture of 3 mL of nitric acid and 10 mL of water, filter, wash with 5 mL of water, and evaporate the filtrate on a steam bath to dryness. Powder the residue, and dry it at 120 for 3 hours. Reflux the dried powder with 15 mL of dehydrated alcohol for 10 minutes, cool in ice, and filter. Repeat the extraction with 10 mL of dehydrated alcohol. Evaporate the combined filtrates to dryness, add 0.5 mL of sulfuric acid, and ignite: the weight of the residue is not more than 10 mg (0.3% of Ca).

Chloride (Reagent test)— One g shows not more than 0.1 mg of Cl (0.01%).

Heavy metals (Reagent test): 0.001%.

Iron 241— Dissolve 1.0 g in 45 mL of water, and add 2 mL of hydrochloric acid: the solution shows not more than 0.01 mg of Fe (0.001%).

Alkali salts— Dissolve 2 g in 80 mL of water, heat to boiling, add an excess of ammonium carbonate TS, boil for 5 minutes, dilute with water to 100 mL, and filter. Evaporate 50 mL of the filtrate, and ignite: the residue after correcting for the ignition residue from half the volume of the clear ammonium carbonate TS used above, is not more than 3 mg (0.3%).

Nitrate— Dissolve 1 g in 10 mL of water, add 0.10 mL of indigo carmine TS, and then add 10 mL of sulfuric acid: the blue color persists for 5 minutes (about 0.01% of NO3).

Assay and carbonate— Accurately weigh about 5 g, dissolve in 200 mL of warm carbon dioxide-free water in a glass-stoppered, 500-mL flask, add phenolphthalein TS, and titrate with 1 N hydrochloric acid VS to determine the hydroxide alkalinity. Then add methyl orange TS, and titrate with 1 N hydrochloric acid VS. Each mL of 1 N hydrochloric acid required to reach the phenolphthalein endpoint is equivalent to 132.9 mg of Sr(OH)2·8H2O, and each additional mL of 1 N hydrochloric acid VS required to reach the methyl orange endpoint is equivalent to 73.8 mg of SrCO3. Not less than 95.0% of Sr(OH)2·8H2O and not more than 3.0% of SrCO3 are found.

Chloride (Reagent test)— Dissolve 1.0 g in 100 mL of water, and filter if necessary: 1.0 mL of the solution shows not more than 0.01 mg of Cl (0.1%).

Calcium (Reagent test)— Dissolve 5.0 g in water, and dilute with water to 100 mL, to obtain the test solution.

Iron— Dissolve 1 g in warm water, and dilute with water to 100 mL. To 20 mL of this solution add 2 mL of hydrochloric acid and 0.1 mL of 0.1 N potassium permanganate, allow to stand for 5 minutes, and add 3 mL of ammonium thiocyanate solution (3 in 10). Any red color produced is not darker than that of a control containing 0.03 mg of added Fe (0.015%).

Heavy metals— To 5.0 mL of test solution add 0.02 mg of lead (Pb), and dilute with water to 30 mL, to provide the standard. For the test specimen, use 30 mL of test solution. Adjust each solution with diluted acetic acid or ammonia TS to a pH between 3.0 and 4.0 (using short-range pH paper), dilute with water to 40 mL, and add 10 mL of freshly prepared hydrogen sulfide TS: any brown color developed in the sample solution is not darker than that in the control solution (0.004%).

Solubility— A solution of 500 mg in 25 mL of water is complete, clear, and colorless.

Residue on ignition (Reagent test): not more than 0.1%.

Brucine— To 100 mg add 1 mL of dilute nitric acid (1 in 2): a yellow color may be observed, but not a red or reddish-brown color.

Assay— When tested by thin-layer chromatography (see Chromatography 621) with the use of plates coated with chromatographic silica gel mixture and a developing system consisting of a mixture of hexane and ethyl acetate (80:20), and examined under short-wavelength UV light, a single spot is exhibited, with trace impurities.

Assay— Transfer about 25 mg, accurately weighed, to a 100-mL volumetric flask. Dissolve in chloroform, dilute with chloroform to volume, and mix. Dilute 2.0 mL of the resulting solution with chloroform to 50.0 mL. Determine the absorbance of this solution in 1-cm cells at the wavelength of maximum absorbance at about 520 nm, with a suitable spectrophotometer, using chloroform as the blank. Calculate the percentage of Sudan IV in the test specimen taken by the formula: in which A is the absorbance at 520 nm and C is the concentration of the test specimen in g per L. Not less than 90% is found.

Loss on drying 731— Dry it at 105 for 2 hours: it loses not more than 10% of its weight.

Measuring range: 1 to 25 ppm.

Fluorescence— Using a suitable fluorometer having a sharp cut-off 360-nm excitation filter and a sharp cut-off 415-nm excitation filter, determine the fluorescence of the sulfuric acid in a cuvette previously rinsed with water followed by several portions of the acid under examination: the fluorescence does not exceed that of quinine sulfate solution (1 in 1,600,000,000), similarly measured.