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 α‐ and β‐ 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 α‐globin was much more reactive than the β‐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 α‐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 epichlorohydrinHb hemoglobinGC/MS gas chromatography/mass spectrometryESMS electrospray mass spectrometryMALDI‐MS matrix‐assisted laser desorption/ionization mass spectrometryMS/MS tandem mass spectrometryLC liquid chromatographyRP‐HPLC reversed‐phase high‐performance liquid chromatographyTFA trifluoroacetic acidSIM selected ion monitoring  u, mass unit. The standard one‐or three‐letter code has been used for the amino acids.