SIMULTANEOUS DETERMINATION OF 14 CATECHOLAMINES AND THEIR METABOLITES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

A simple method has been developed for simultaneous determination of 14 catecholamines and their metabolites in cerebrospinal fluid and brain tissue by reversed-phase, ion-pair high-performance liquid chromatography with electrochemical detection. The time required for complete separation and analysis of all compounds was less than 35 min. Quantitation was based on the use of an internal standard isoproterenol. The mobile phase consisted of a 91:9 (v/v) mixture of 0.1 M formic acid and acetonitrile containing sodium-1-octane sulfonic acid. Using this method, analysis of neurotransmitters in brain tissue can be accomplished without a clean-up procedure. The detection limits for the four compounds examined, namely 3-methoxy-4-hydroxyphenylglycol, 3,4-dihydroxyphenylacetic acid, 5-hydroxyindoleacetic acid and homovanillic acid were less than 10 pg per injection. In the cerebrospinal fluid, linear responses of the above 4 compounds were observed over the concentration range from 3.1 to 50.0 ng/ml. The coefficients of variation from 5 consecutive assays were less than 2.90% while the averaged recoveries were more than 93.37%.