A: Ultraviolet Absorption á197Uñ—

B: Dissolve about 400mg in 10mLof water,add 1mLof 3Nhydrochloric acid,filter,and wash the precipitate with two 5-mLportions of cold water.Recrystallize from alcohol the precipitate so obtained,and dry at 110for 1hour:the p-aminobenzoic acid so obtained melts between 186and 189.

C: Asolution (1in 100)meets the requirements of the flame test for Sodium á191ñ.

Standard solution— Dissolve 10mg of p-toluidine in 5mLof methanol in a 100-mLvolumetric flask,dilute with water to volume,and mix.Transfer 1mLto a 100-mLvolumetric flask,dilute with water to volume,and mix.

Test solution— Transfer 5.0g of Aminobenzoate Sodium to a suitable flask,and add a volume of 1.25Nsodium hydroxide that is just sufficient to dissolve the test specimen and to render the solution just alkaline to phenolphthalein TS.Dilute with water to 50mL,and steam-distill the solution,collecting about 95mLof the distillate in a 100-mLvolumetric flask.Dilute with water to volume,and mix.

Procedure— Transfer 20.0-mLportions of the Standard solutionand the Test solutionto separate 100-mLbeakers,and transfer 20.0mLof water to a third 100-mLbeaker to provide the blank.Treat each as follows.Add 5.0mLof 1Nhydrochloric acid,and cool in an ice bath.Add 2.0mLof 0.1Msodium nitrite dropwise,with stirring,allow to stand for 5minutes for the diazotization reaction to be complete,add quickly to 10.0mLof a cold solution of guaiacol (freshly prepared by dissolving 0.20g of guaiacol in 100mLof 1Nsodium hydroxide),mix,and allow to stand for 30minutes.Concomitantly determine the absorbances of the solutions at the wavelength of maximum absorbance at about 405nm,with a suitable spectrophotometer,using the blank to set the instrument:the absorbance of the solution obtained from the Test solutiondoes not exceed that of the solution obtained from the Standard solution,corresponding to not more than 0.002%of volatile diazotizable substances,as p-toluidine.