SIMULTANEOUS ANALYSIS OF HOMOVANILLIC-ACID, 5-HYDROXYINDOLEACETIC ACID, 3-METHOXY-4-HYDROXYPHENYLETHYLENE GLYCOL AND VANILMANDELIC ACID IN PLASMA FROM ALCOHOLICS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION - CRITICAL COMPARISON OF SOLID-PHASE AND LIQUID-LIQUID-EXTRACTION METHODS

A method is described for the simultaneous determination of vanilmande lic acid, 3-methoxy-4-hydroxyphenylethylene glycol, 5-hydroxyindoleace tic acid, and homovanillic acid in a human plasma sample using reverse d-phase high-performance liquid chromatography with column switching a nd amperometric detection. Two methods of sample preparation were test ed. Liquid-liquid extraction yields better recoveries, is more selecti ve and precise than solid-phase extraction and allows a shorter time o f chromatographic analysis. Estimated plasma values of the metabolites from healthy controls are in good agreement with previously reported levels. Studies of alcoholics at the beginning of the delirium tremens provided different plasma levels of the metabolites, dependent on the different duration-and hence the severity-of the delirium.