Liquid-chromatographic determination of free and total 3,4-dihydroxyphenylglycol and 3-methoxy-4-hydroxyphenylglycol in urine.

We describe the conjoint measurement in urine of the alcoholic catecholamine metabolites 3,4-dihydroxyphenylglycol (DHPG) and 3-methoxy-4-hydroxyphenylglycol (MHPG). The method involves extraction with ethyl acetate and back-extraction into acetic acid (MHPG), followed by adsorption onto alumina (DHPG). The separation is performed by reversed-phase liquid chromatography with column switching and amperometric detection. Total (free plus conjugated) compounds are determined after a 24-h enzymatic hydrolysis. Twelve-hour excretion values for normal and hypertensive subjects are given, together with results obtained for patients with pheochromocytoma, chemodectoma, and congenital dopamine-beta-hydroxylase deficiency. The assay is sensitive, reproducible, and free of interferences, and may lead to a better understanding of overall catecholamine metabolism in health and disease.