Determination of 4,4′-methylenebis(2-chloroaniline) in urine using capillary gas chromatography and negative ion chemical ionization mass spectrometry

Abstract

A highly sensitive and specific gas chromatographic–mass spectrometric (GC–MS) assay for the determination of 4,4′-methylenebis(2-chloroaniline)(MBOCA) in urine is reported. It is based on the solvent extraction of the hydrolysed MBOCA conjugates, together with deuterium-labelled benzidine-d₈ added as an internal standard, and a two-phase derivatization procedure involving use of pentafluoropropionic anhydride in the presence of ammonia as the phase-transfer catalyst. The reaction is complete within 2 min at room temperature. The pentafluoropropyl derivatives are determined by use of capillary column GC—MS with selected-ion monitoring in the negative ion chemical ionization mode. The lower limit of detection for MBOCA was 1 µg dm^–3 and the calibration graph showed linearity between 10 and 250 µg dm^–3. The recovery of the analyte added to pooled urine was above 86%. Thirty urine specimens from workers employed in a polyurethane-producing plant were analysed for MBOCA by this method.