LC-MS/MS method for the confirmatory determination of aromatic amines and its application in textile analysis

A confirmation method for the determination of 18 aromatic amines originating from azo dyes after reductive cleavage was developed. The method is based on the use of high-performance liquid chromatography/tandem mass spectrometry with atmospheric-pressure chemical ionization. For the identification of the analytes one precursor ion and two daughter ions (multi-reaction monitoring, MRM) were selected and the LC-MS/MS parameters optimized to obtain high sensitivity and selectivity. The linear ranges varied from 0.1-1 to 30-50 microg mL(-1) with correlation coefficients of 0.99 or better. The applicability of the method to determine o-tolidine (3,3'-dimethylbenzidine) and 3,3'-dimethoxybenzidine in textiles following reductive cleavage of acid red 114, trypan blue, and Chicago sky blue 6B was demonstrated.