ISOTOPE-DILUTION AMMONIA CHEMICAL-IONIZATION MASS FRAGMENTOGRAPHIC ANALYSIS OF URINARY 3-O-METHYLATED CATECHOLAMINE METABOLITES - RAPID SAMPLE CLEANUP BY DERIVATIZATION AND EXTRACTION OF LYOPHILIZED SAMPLES

We developed a method for simultaneous quantification of the urinary 3 -O-methylated catecholamine metabolites 3-methoxytyramine, normetaneph rine and metanephrine by stable isotope-dilution ammonia chemical ioni zation mass fragmentography. Prepurification of lyophilized samples wa s done by simultaneous deconjugation and pentafluoropropionylation, fo llowed by extraction and rederivatization. Compared with our previousl y described method, based on acid hydrolysis, alkaline extraction, der ivatization and electron-impact mass fragmentography, the present meth od was found to be less laborious, more sensitive and presumably more accurate. New urinary excretion values were established for apparently healthy adults. The present prepurification method may prove applicab le for profiling of a variety of naturally occurring mono-, di- and po lyamines in biological samples.