DETERMINATION OF METHYLATED GLOBIN AND ALBUMIN FOR BIOMONITORING OF EXPOSURE TO METHYLATING AGENTS USING HPLC WITH PRECOLUMN FLUORESCENT DERIVATIZATION

A new method has been developed for the quantitation of methylated blo od proteins in persons exposed to methylating agents. Using different derivatizing agents, 9-fluorenylmethyl chloroformate was the most suit able with regard to both sensitivity and peak separation after subsequ ent HPLC. After optimization of the chromatographic conditions, two gr oups who worked with methyl bromide and a control group of non exposed persons were compared with regard to their adduct rates (S-methylcyst eine) in the two blood proteins albumin and globin. Albumin and globin were isolated from whole blood samples. After total hydrolysis of the proteins with hydrochloric acid, an amino acid analysis was performed using HPLC with precolumn fluorescent derivatization. This method ena bled a quantitation of methylated cysteine in the fmol range. Backgrou nd levels of S-methylcysteine (15 nmol/g protein) in both albumin and globin were found in non-exposed control persons. Levels were up to 10 fold higher in exposed fumigators working with the methylating agent methyl bromide.