The determination of 4-aminobiphenyl in refined aniline

Abstract

A method has been developed for the determination of from 2 mg per litre, upwards, of 4-aminobiphenyl in refined aniline. The bulk of the aniline is separated by distilling the sample in the presence of paraffin wax, which retains 75 per cent. of the 4-aminobiphenyl. An acid extract of the distillation residue is diazotised and coupled with sodium 2-naphthol 3, 6-disulphonate (R-salt). The dyestuffs resulting from 4-aminobiphenyl and residual aniline are separated by circular-paper chromatography, and the former is determined by visual comparison of the corresponding ring on the chromatogram with standards prepared from aniline containing known concentrations of 4-aminobiphenyl.