Isotope dilution ammonia chemical ionization mass fragmentographic analysis of urinary 3-O-methylated catecholamine metabolites. Rapid sample clean-up by derivatization and extraction of lyophilized samples.

We developed a method for simultaneous quantification of the urinary 3-O-methylated catecholamine metabolites 3-methoxytyramine, normetanephrine and metanephrine by stable isotope-dilution ammonia chemical ionization mass fragmentography. Prepurification of lyophilized samples was done by simultaneous deconjugation and pentafluoropropionylation, followed by extraction and rederivatization. Compared with our previously described method, based on acid hydrolysis, alkaline extraction, derivatization and electron-impact mass fragmentography, the present method 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 applicable for profiling of a variety of naturally occurring mono-, di- and polyamines in biological samples.

Simultaneous determination of the four major catecholamine metabolites and estimation of a serotonin metabolite in urine by capillary gas chromatography of their tert-butyldimethylsilyl derivatives.

We have developed a routine capillary gas-chromatographic profiling method for simultaneous quantitative determination of the tert-butyldimethylsilyl derivatives of homovanillic acid, vanilmandelic acid, 3-methoxy-4-hydroxyphenylethylene glycol, and 3,4-dihydroxyphenylacetic acid and the estimation of 5-hydroxyindole-3-acetic acid in urine. The method is useful for diagnosis and followup of patients with functional tumors characterized by increased urinary excretion of metabolites originating from the metabolism of tyrosine and tryptophan--e.g., neuroblastoma, pheochromocytoma, carcinoid, and melanoma. It may also be applicable in pharmacokinetic studies of administered aromatic amino acids (parkinsonism, mental diseases, loading tests) and for diagnosis and followup of patients with inborn errors of metabolism that are characterized by organic aciduria (for instance, tyrosyluria and phenylketonuria).