Packaging and storage— Preserve in tight,light-resistant containers.

Assay for parachlorophenol— Transfer about 1g of Camphorated Parachlorophenol,accurately weighed,to a wide-mouth conical flask,and add a few glass beads,6mLof sodium hydroxide solution (1in 2),and 130mLof water.Heat the solution to boiling,add 70mLof potassium permanganate solution (3in 50),and continue to boil for 20minutes.To the hot solution add 40mLof 0.1Nsilver nitrate.Add 50mLof 18Nsulfuric acid,and sodium sulfite crystals,in divided portions and with swirling until the permanganate color is discharged and no manganese dioxide remains.Boil until the vapors are no longer acid to litmus,keeping the volume nearly constant by the addition of water.Add 5mLof nitric acid,and continue to boil for 5minutes.Cool,and collect the precipitate on a tared filtering crucible,wash well with water,then with 10mLof alcohol,dry at 105for 1hour,cool,and weigh.Each 1.000g of the silver chloride so obtained is equivalent to 897.0mg of C6H5ClO.

Assay for camphor— Transfer about 300mg of Camphorated Parachlorophenol,accurately weighed,to a 200-mLpressure bottle containing 50mLof freshly prepared dinitrophenylhydrazine TS.Close the pressure bottle,immerse it in a water bath,and maintain it at about 75for 4hours.Cool to room temperature,then transfer the contents to a beaker with the aid of 100mLof 3Nsulfuric acid and allow it to stand overnight.Collect the precipitate on a tared filtering crucible,wash with 100mLof 3Nsulfuric acid and then with 75mLof cold water,in divided portions,to remove the acid.Dry at 80for 2hours,cool,and weigh.The weight of the precipitate so obtained,multiplied by 0.4581,represents the weight of C10H16Oin the sample taken.

Expert Committee:(PA7)Pharmaceutical Analysis 7

USP28–NF23Page 1467

Phone Number:1-301-816-8394