A: Infrared Absorption á197Kñ.

B: Thin-Layer Chromatographic Identification Test á201ñ—The RFvalue of the principal spot obtained from Test solution 1in the test for Related compoundscorresponds to that of the principal spot obtained from Standard solution 1.

C: Add 20mg of Allantoin to a mixture of 1mLof 2Msodium hydroxide and 1mLof water.Heat to boiling,allow to cool,and add 1mLof 2Mhydrochloric acid.To 0.1mLof this solution add 0.1mLof potassium bromide solution (1in 10),0.1mLof resorcinol solution (2in 100),and 3mLof sulfuric acid.Heat on a water bath for 5to 10minutes:a dark blue color,which turns red after cooling and pouring into about 10mLof water,is observed.

Test solution: 10mg per mL,in carbon dioxide-free water.[NOTE—Reserve a portion of this solution for use in the test for Acidity or alkalinity.]

Adsorbent: cellulose.

Test solution 1— Transfer about 0.10g of Allantoin,accurately weighed,to a 10-mLvolumetric flask,add 5mLof water,dissolve by heating,and allow to cool.Dilute with methanol to volume,and mix.[NOTE—Use immediately after preparation.]

Test solution 2— Transfer 1mLof Test solution 1to a 10-mLvolumetric flask,dilute with a mixture of methanol and water (1:1)to volume,and mix.

Standard solution 1— Transfer about 10mg of USP Allantoin RS,accurately weighed,to a 10-mLvolumetric flask,dissolve in and dilute with a mixture of methanol and water (1:1)to volume,and mix.

Standard solution 2— Transfer about 10mg of USP Urea RS,accurately weighed,to a 10-mLvolumetric flask,dissolve in and dilute with water to volume,and mix.Transfer 1.0mLof this solution to a 10-mLvolumetric flask,dilute with methanol to volume,and mix.

Standard solution 3— Mix 1mLof Standard solution 1and 1mLof Standard solution 2.

Developing solvent system: a mixture of butyl alcohol,water,and glacial acetic acid (60:25:15).

Spray reagent— Dissolve a quantity of p-dimethylaminobenzaldehyde in a mixture of methanol and hydrochloric acid (3:1)to obtain a solution having a concentration of 5g per L.

Procedure— Proceed as directed for Thin-Layer Chromatographyunder Chromatography á621ñ.Separately apply to the chromatographic plate 10µLof Test solution 1and 5µLeach of Test solution 2,Standard solution 1,Standard solution 2,and Standard solution 3.Develop the chromatogram until the solvent front has moved about 10cm.Spray the plate with Spray reagent,dry in a current of hot air,and after 30minutes examine under visible light.Any spot in the chromatogram obtained from Test solution 1,except for the principal spot,is not more intense than the spot in the chromatogram obtained from Standard solution 2:not more than 0.5%of any individual impurity is found.The test is not valid unless the principal spots in the chromatogram obtained from Standard solution 3are clearly separated.