Analysis of the glutathione conjugate of paracetamol in human liver microsomal fraction by liquid chromatography mass spectrometry.

An assay based on microbore liquid chromatography-positive ion electrospray mass spectrometry with selected ion recording has been developed for the measurement of the glutathione conjugate of paracetamol (acetaminophen) in human hepatic microsomal incubations. A deuterated analogue of the glutathione conjugate was synthesized for use as an internal standard and extraction was carried out on Oasis solid phase extraction columns. The limit of quantification of the glutathione conjugate was 10 ng/incubation and the intra-assay coefficient of variation at this concentration was 6.8%.