Mass spectrometric identification of a candidate biomarker peptide from the in vitro interaction of epichlorohydrin with red blood cells.

The reaction products of epichlorohydrin with human alpha- and beta- globins, obtained through in vitro incubation of these compounds and red blood cells, were determined by using reversed-phase high-performance liquid chromatography (RP-HPLC), electrospray ionization mass spectrometry and matrix-assisted laser desorption/ionization tandem mass spectrometry. The alpha-globin was much more reactive than the beta-globin. At low incubation ratios, approximating the order of magnitude of epichlorohydrin concentration as found in workplaces, the only modified peptide still detectable was the 62-90 belonging to the alpha-chain and carrying an incremental mass of 92 u on either His72 or His89. Given that the two peptides co-eluted in a single chromatographic peak during RP-HPLC separation, they could be chosen as suitable biomarkers for quantification in the setting up of a new methodology for the biological monitoring of persons occupationally exposed, replacing currently known procedures. Copyright 2001 John Wiley & Sons, Ltd. Abbreviations: ECH epichlorohydrin Hb hemoglobin GC/MS gas chromatography/mass spectrometry ESMS electrospray mass spectrometry MALDI-MS matrix-assisted laser desorption/ionization mass spectrometry MS/MS tandem mass spectrometry LC liquid chromatography RP-HPLC reversed-phase high-performance liquid chromatography TFA trifluoroacetic acid SIM selected ion monitoring u, mass unit. The standard one-or three-letter code has been used for the amino acids.