Analysis of S-phenyl-L-cysteine in globin as a marker of benzene exposure

An assay has been developed to determine S-phenylcysteine (SPC) in globin a s a potential biomarker for exposure to benzene. The sensitivity of the ass ay is less than 20 pmol SPC g(-1) globin. Following acidic hydrolysis of th e protein, the modified amino acid is purified by reverse phase cartridge c hromatography and HPLC, prior to conversion to the tert-butyldimethylsilyl derivative and GC-MS selected ion recording. Quantitation is achieved using the internal standard [H-2(5)]-SPC, and calibration lines were established using a synthetic peptide Leu-His-SPC-Asp-Lys. Control human globin was fo und to contain ca 30 pmol SPC g(-1) globin in two populations. The source o f the apparent background level of SPC is unknown.