A: Infrared Absorption á197Kñ.

B: Ultraviolet Absorption á197Uñ—

Solution: 5µg per mL.

Medium: 0.001Nsodium hydroxide.

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

Test preparation— Transfer 5.0g of Aminobenzoic Acid 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.Add water to volume,and mix.

Procedure— Transfer 20.0-mLportions of the Standard preparationand the Test preparationto 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 in order 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 in 1-cm cells at the wavelength of maximum absorbance at about 450nm,using the blank to set the instrument:the absorbance of the solution obtained from the Test preparationdoes not exceed that of the solution obtained from the Standard preparation,corresponding to not more than 0.002%of volatile diazotizable substances,as p-toluidine.

Test solution: alcohol.

Standard solution: alcohol.

Eluant: a mixture of toluene,ethyl acetate,and alcohol (60:20:20),in a nonequilibrated chamber.

Visualization: 1.