Chloride— Transfer about 80mg,accurately weighed,to a suitable beaker.Add 25mLof acetone,25mLof water,and 500mg of sodium nitrate.Stir until solution is complete.Titrate with 0.01Nsilver nitrate VS,determining the endpoint potentiometrically.Perform a blank determination and make any necessary correction.Not less than 15.0%of chloride is found.

Loss on drying á731ñ— Dry it in vacuum at 110for 1hour:it loses not more than 5.0%of its weight.

Absorbance— Dissolve 50mg in 100mLof water.In a second container dissolve 100mg of 2-naphthol in 100mLof 2-methoxyethanol.Pipet 5mLof the test solution and 10mLof the 2-naphthol solution into a 100-mLvolumetric flask,and dilute with acetone to volume.For the blank,pipet 5mLof water and 10mLof 2-naphthol solution into a second 100-mLvolumetric flask,and dilute with acetone to volume.Determine the absorbance of the test solution in a 1-cm cell at the wavelength of maximum absorbance at about 545nm,with a suitable spectrophotometer,using the blank to set the instrument:the absorbance is not less than 0.80.

Assay— Accurately weigh about 1g,dissolve in 25mLof water in a glass-stoppered flask,add 5mLof hydrochloric acid and 4g of potassium iodide,insert the stopper in the flask,and allow to stand in the dark for 15minutes.Add 100mLof water,and titrate the liberated iodine with 0.1Nsodium thiosulfate VS,adding 3mLof starch TSas the endpoint is approached.Perform a blank determination,and make any necessary correction.Each mLof 0.1Nsodium thiosulfate is equivalent to 5.585mg of Fe:between 16.5%and 18.5%is found.

Ferric citrate— To 250mg dissolved in 25mLof water add 1mLof potassium ferrocyanide TS:no blue precipitate is formed.

Tartrate— Dissolve 1g in 10mLof water,add 1mLof potassium hydroxide TS,boil to coagulate the ferric hydroxide,adding more potassium hydroxide TS,if necessary,to precipitate all of the iron,filter,and slightly acidify the filtrate with glacial acetic acid.Add 2mLof glacial acetic acid,and allow to stand for 24hours:no crystalline white precipitate is formed.

Lead á251ñ— Dissolve 1.0g in 30mLof water,add 5mLof dilute nitric acid (1in 21),boil gently for 5minutes,cool,and dilute with water to 50mL:20mLof the solution shows not more than 0.008mg of Pb (0.002%).

Assay— Accurately weigh about 700mg,and dissolve it in a mixture of 50mLof water and 3mLof hydrochloric acid in a glass-stoppered flask.Add 3g of potassium iodide,and allow to stand in the dark for 30minutes.Then dilute with 100mLof water,and titrate with 0.1Nsodium thiosulfate VS,adding 3mLof starch TSas the endpoint is approached.Each mLof 0.1Nsodium thiosulfate is equivalent to 5.585mg of Fe:not less than 21.0%and not more than 23.0%is found.

Insoluble matter(Reagent test)— A10-g portion,dissolved in a mixture of 100mLof water and 5mLof sulfuric acid,shows not more than 2mg of insoluble matter (0.02%).

Chloride— Dissolve 1g by warming with a mixture of 10mLof water and 1mLof nitric acid,add 4mLof additional nitric acid,and dilute with water to 50mL.To 25mLadd 1mLof phosphoric acid and 1mLof silver nitrate TS.Any turbidity does not exceed that produced in a control containing 0.01mg of chloride ion (Cl),1mLof nitric acid,1mLof phosphoric acid,and 1mLof silver nitrate TS(0.002%).

Ferrous iron— Dissolve 4g by warming with 50mLof dilute sulfuric acid (1in 10),cool,and titrate with 0.1Npotassium permanganate:not more than 0.16mLis required to produce a permanent pink color (0.02%as Fe+2). [NOTE—Since the reagents used in the tests for Copperand Zincmay contain excessive amounts of copper and zinc,they should first be purified by extracting with Dithizone Extraction Solution(see Lead á251ñ).]

Copper— Dissolve 1.2g in 100mLof water.To 10mLadd 50mLof a solution containing 5g of ammonium tartrate and 5mLof ammonium hydroxide.Add 10mLof Standard Dithizone Solution(see Lead á251ñ),shake for 2minutes,draw off the dithizone layer,and compare the pink color with that in a control containing 6µg of copper ion (Cu)and treated exactly as the 10-mLportion of test solution.If the color in the test solution is less than that in the control,then the test specimen contains less than the limit of both Copperand Zinc.If the color in the test solution is more than that in the control,add 15mLof dilute hydrochloric acid (1in 250),and shake for 2minutes.Draw off the dithizone solution,and shake with a second 15mLof dilute hydrochloric acid (1in 250)for 2minutes.Draw off the dithizone,combine the two acid extracts,and reserve for the Zinctest.Any pink color in the dithizone solution is not darker than that in the control solution treated exactly as the test solution (0.005%).

Zinc— To the combined acid extracts saved from the Coppertest,add 0.5Msodium acetate to bring the pHbetween 5.0and 5.5,and then add 1mLof 0.1Nsodium thiosulfate.Add 10mLof Standard Dithizone Solution(see Lead á251ñ),shake for 2minutes,and allow the layers to separate.Draw off the dithizone,and discard the water layer.Any pink color is not greater than that in a control prepared by adding 0.006mg of zinc ion (Zn)to the combined acid extracts from the control used in the test for Copper(0.005%).

Nitrate— Dissolve 10g in 100mLof dilute sulfuric acid (1in 100),heat to boiling,and pour,slowly,into a mixture of 140mLof water and 50mLof stronger ammonia TS.Filter through a folded filter while still hot,wash with hot water until the volume of the filtrate is 300mL,mix,and cool.To 15mLof this solution add 1mLof sodium chloride solution (1in 200),0.10mLof indigo carmine TS,and 15mLof sulfuric acid.The blue color is not completely discharged at the end of 5minutes (0.01%).

Substances not precipitated by ammonia— Evaporate to dryness 30mLof the filtrate obtained in the test for Nitrate,and ignite gently:the weight of residue does not exceed 1mg (0.10%).

Water,Method Iá921ñ: not more than 10%.

Add the following:

Solubility test— One g dissolves in 10mLof acetone to yield a clear and complete solution.

Melting range á741ñ: between 113and 117,within a 2range.

Add the following:

Assay— Dissolve about 600mg in 75mLof dimethylformamide,and titrate with 0.1Nlithium methoxide to a blue end-point,using 1%thymol blue in dimethylformamide as the indicator.Perform a blank determination,and make any necessary correction.Each mLof 0.1Nlithium methoxide is equivalent to 27.83mg of C17H10O4.Not less than 99%is found.

Loss on drying á731ñ— Dry it at 105for 4hours:it loses not more than 0.5%of its weight.

Assay— Inject an appropriate specimen into a suitable gas chromatograph (see Chromatographyá621ñ)equipped with a flame-ionization detector,helium being used as the carrier gas.The following conditions have been found suitable:a 25-mm ×30-m capillary column coated with a 1-µm layer of phase G2;the injection port temperature is maintained at 200;the detector temperature is maintained at 250;the column temperature is maintained at 100and programmed to rise 10per minute to 250.The area of the FC6H4COCH3peak is not less than 99%of the total peak area.

Refractive index á831ñ: 1.510at 20.

Preparation for Digitoxin Assay— To ensure freedom from ammonia,treat Formamide as follows.Shake a suitable quantity of formamide with about 10%of its weight of anhydrous potassium carbonate for 15minutes,and filter.Distill the filtrate in all-glass apparatus under vacuum at a pressure of about 25mm of mercury or less.Reject the first portion of distillate containing water,and collect the fraction that boils at about 115at a pressure of 25mm of mercury or at 101at a pressure of 12mm of mercury.Store in tight containers,protected from light.

Loss on drying á731ñ— Dry it at 105to constant weight:it loses not more than 5.0%of its weight.

Residue on ignition(Reagent test)— Ignite 1g with 0.5mLof sulfuric acid:the residue weighs not more than 3mg (0.3%).

Powder fineness— See Powder Fineness á811ñ.

Soluble matter— Twenty g,treated with 50mLof cold water and filtered,yields not more than 60mg of residue upon evaporation of the filtrate (0.3%).Asecond 20-g portion,treated with 50mLof cold alcohol and filtered,yields not more than 14mg upon evaporation of the filtrate (0.07%).

Loss on drying á731ñ— Dry it at 105for 6hours:it loses between 7.0%and 10.0%of its weight.

Boiling range (Reagent test)— Not less than 95%distils between 159and 162.