Gas chromatographic determination and negative-ion chemical ionization mass spectrometric confirmation of 4,4'-methylenebis(2-chloroaniline) in urine via thin-layer chromatographic separation.

An analytical method for monitoring 4,4'-methylenebis(2-chloroaniline) (MOCA) in urine was developed. The MOCA extract from a urine sample was derivatized with pentafluoropropionic anhydride and subsequently cleaned-up via TLC before being analysed by a gas chromatograph equipped with an electron capture detector. Heptafluorobutyric anhydride derivatized MOCA was used as the internal standard during quantification. The method showed that the analytical interferences are effectively minimized by using the TLC technique for sample clean-up. Recoveries of spiked MOCA in urine at levels of 7.5, 22 and 62.5 micrograms dm-3 were all over 90% with the limit of detection determined to be 1 microgram dm-3. Confirmation of MOCA in a urine sample was performed by using a gas chromatograph mass spectrometer in negative-ion chemical ionization mode.