Melting range á741ñ: between 80and 81.

Boiling range(Reagent test): between 217and 219.

Melting range á741ñ: between 122and 127.

Solubility in methanol— Dissolve 500mg in 50mLof methanol:the solution is clear and complete.

Melting range á741ñ: between 187and 191.

Assay— Dissolve about 1g,accurately weighed,in 100mLof water,add phenolphthalein TS,and titrate with 0.1Nsodium hydroxide VS.Perform a blank determination,and make any necessary correction.Each mLof 0.1Nsodium hydroxide is equivalent to 22.63mg of C10H8O3S·H2O.Not less than 98.0%is found.

Melting range á741ñ: between 122and 126,but the range between beginning and end of melting does not exceed 2.

Melting range á741ñ: between 95and 97.

Solubility— Separate 1-g portions dissolve in alcohol and in benzene to yield solutions that are clear and colorless or nearly colorless.

Acidity— Shake 1g with 50mLof water occasionally during 15minutes,and filter:the filtrate is neutral to litmus.

Residue on ignition(Reagent test): not more than 0.05%.

Melting range á741ñ: between 121and 123.

Solubility in alcohol— Asolution of 1g in 10mLof alcohol is complete and colorless or practically so.

Residue on ignition(Reagent test): not more than 0.05%.

Acidity— Shake 1g with 50mLof water occasionally during 15minutes,and filter:the filtrate is neutral to litmus.

1-Naphthol— Boil 100mg with 10mLof water until dissolved,cool,and filter.Add to the filtrate 0.3mLof 1Nsodium hydroxide and 0.3mLof 0.1Niodine:no violet color is produced.

Insoluble in ammonia(naphthalene,etc.)— Shake 500mg with 30mLof ammonia TS:the 2-naphthol dissolves completely and the solution is not darker than pale yellow.

Loss on drying á731ñ— Dry it in vacuum at about 50:it loses not more than 2.0%of its weight.

Residue on ignition(Reagent test)— Ignite 1g of dried sample with 3mLof sulfuric acid:the residue weighs between 265and 280mg (between 26.5%and 28.0%).

Residue on ignition(Reagent test)— Ignite 200mg with a few drops of sulfuric acid:the weight of the residue is negligible.

Assay— Dissolve 17.9g of anhydrous dibasic sodium phosphate in water to make 500mL(Solution A).Dissolve 6.8g of monobasic potassium phosphate in water to make 500mL(Solution B).To a volume of Solution A,add Solution Buntil the mixture is adjusted to a pHof 7.0(about 2:1by volume of Solutions Aand B)to obtain a pH7.0Buffer.Transfer about 25mg of b-nicotinamide adenine dinucleotide,accurately weighed,to a 25-mLvolumetric flask,dissolve in and dilute with water to volume,and mix.Transfer 0.2mLof this solution to a 10-mLvolumetric flask,dilute with pH7.0Bufferto volume,and mix.Use this solution as the Assay preparation.Determine the absorbances of the Assay preparationand the pH7.0Bufferin 1-cm cells at a wavelength of 260nm,using water as the reference.Calculate the quantity,in mg,of C21H27N7O14P2in the portion of b-nicotinamide adenine dinucleotide taken by the formula: in which AAand ABare the absorbances of the Assay preparationand the pH7.0Buffer,respectively.Not less than 94.5%is found.

Suitability— When used in the assay of lactulose,determine that a suitable absorbance-versus-concentration slope is obtained,using USP Lactulose RS,the reagent blank absorbance being not more than 0.020.The commercially available reagent contains 64mg of nicotinamide adenine dinucleotide phosphate and 160mg of adenosine-5¢-triphosphate per vial.The mixture is buffered and stabilized.For use in the Assay of lactulose it is diluted with water to 100mL.

Lead— To 100g add 0.1g of anhydrous sodium carbonate and evaporate to dryness.Dissolve the residue in water,heating slightly,and dilute with the same solvent to 50.0mL.Determine the lead content by atomic absorption spectrophotometry (see Spectrophotometry and Light-Scattering á851ñ)measuring the absorbance at 283.3nm or 217.0nm using a lead hollow-cathode lamp and an air–acetylene flame.It contains not more than 0.1ppm of lead (Pb).

Measuring range: 0.5to 10ppm.

Assay— Inject an appropriate ether solution of the specimen (about 0.5µL)into a suitable gas chromatograph (see Chromatography á621ñ)equipped with a thermal conductivity detector,helium being used as the carrier gas.The following conditions have been found suitable:a 4-mm ×1.8-m stainless steel column containing 10%phase G1on support S1A;the injection port and detector are maintained at 200and 300,respectively;the column temperature is maintained at 170and programmed to rise 3per minute to 220.The area of the 4¢-nitroacetophenone peak is not less than 97%of the total peak area.

Melting range á741ñ: between 78and 80.

Melting range á741ñ: between 71and 72.

Melting range á741ñ: between 146and 148.

Solubility— Separate 1-g portions dissolve in 30mLof alcohol and in 40mLof ether,respectively,to yield solutions that are clear or practically so.

Residue on ignition(Reagent test): not more than 0.2%.

Assay— Transfer about 30mg,accurately weighed,to a low-actinic,100-mLvolumetric flask.Dissolve in 0.01Nhydrochloric acid,dilute with 0.01Nhydrochloric acid to volume,and mix.Using low-actinic glassware,dilute 2.0mLof the resulting solution with spectrophotometric grade methanol to 50.0mL.Measure the absorbance of this solution in a 1-cm cell at about 255nm,using methanol as the blank.Calculate the absorptivity of the solution by dividing the measured absorbance by the concentration in g per mL.Calculate the assay value by the formula: in which ais the absorptivity of the solution:not less than 95.0%is found.

Melting range á741ñ: between 98and 100.

Solubility— Separate 200-mg portions yield clear solutions in 5mLof alcohol and in 5mLof glacial acetic acid.

Residue on ignition(Reagent test): negligible,from 200mg.

Insoluble matter— Dissolve 1g in 10mLof acetone:the solution is clear and complete.

Melting range á741ñ: between 71and 74.

Melting range á741ñ: between 198and 200.

Suitability as redox indicator— Dissolve 25mg in a minimum volume of diluted sulfuric acid,add 10mg of ferrous sulfate,and dilute with water to 100mL:the solution is deep red in color and exhibits an absorption maximum at 510nm.To 1.0mLof the solution add 1.0mLof 0.01Mceric sulfate:the red color is discharged.

Assay— Transfer about 250mg,previously dried over silica gel to constant weight and accurately weighed,to a glass-stoppered flask,and dissolve in 10mLof sodium hydroxide solution (1in 10).Cool the solution in an ice bath,add dilute sulfuric acid (1in 6)until a slight,permanent precipitate is formed and the solution is slightly acid,then add 3g of potassium iodide,shake to dissolve,add 20mLof dilute sulfuric acid (1in 6),immediately insert the stopper in the flask,and allow to stand in the dark for 2hours.Titrate the liberated iodine with 0.1Nsodium thiosulfate VS,adding 3mLof starch TSas the end-point is approached.Perform a complete blank determination,and make any necessary correction.Each mLof 0.1Nsodium thiosulfate is equivalent to 8.66mg of C10H7NO2:not less than 95.0%is found.

Melting range á741ñ: between 109and 111.

Residue on ignition(Reagent test): not more than 0.2%.

Sensitiveness— Dissolve 500mg of sodium acetate in a solution of 0.4mg of cobaltous chloride (0.1mg of cobalt)in 5mLof water.Add 1mLof diluted acetic acid,and follow with 1mLof a solution of the nitroso Rsalt (1in 500):a red color,which is produced at once,persists when the solution is boiled with 1mLof hydrochloric acid for 1minute.

Assay— Inject an appropriate specimen into a suitable gas chromatograph (see Chromatography á621ñ)equipped with a thermal conductivity detector,helium being used as the carrier gas.The following conditions have been found suitable:3-mm ×1.8-m stainless steel column containing 5%phase G2on support S1AB;the injection port temperature is maintained at 330;the detector temperature is maintained at 300;and the oven temperature is held initially at 190and allowed to rise gradually to 250.The area of the nonadecane peak is not less than 99%of the total peak area.

Melting range á741ñ: between 31.5and 33.5.

Assay— Accurately weigh about 500mg,transfer to a suitable container,add 30mLof water,and mix.Add 40mLof water,and mix.Add phenolphthalein TS,and titrate with 0.1Nsodium hydroxide VS.Each mLof 0.1Nsodium hydroxide is equivalent to 15.82mg of C9H18O2:not less than 96.0%of C9H18O2is found.

Refractive index á831ñ: about 1.432at 20.

Assay— Not less than 97%of C9H20Ois found,a suitable gas chromatograph equipped with a flame-ionization detector and helium being used as the carrier gas at a flow rate of about 40mLper minute.The following conditions have been found suitable:a 3.2-mm ×1.83-m stainless steel column packed with 20%phase G16on support S1A;the injection port,column,and detector temperatures are maintained at about 250,160,and 310,respectively.

Refractive index á831ñ: between 1.432and 1.434at 20.