SimultaneousDeterminationof Four Monoamine Metabolitesand Serotoninin Cerebrospinal Fluidby “High-Performance”LiquidChromatographywith ElectrochemicalDetection;Application

We describe an optimized, sensitive assay procedure for simultaneouslydetermining3-methoxy-4-hydroxyphenylgly-col, 3,4-dihydroxyphenylacetic acid, homovanillic acid, 5-hydroxyindoleaceticacid, and serotonin in human lumbar cerebrospinalfluid.The assay is based on liquidchromatog-raphy with an electrochemical detection system equipped with a newly developed, highlysensitivegraphite electrode. Before assay, samples are deproteinized with perchloric acid, 0.2 mol/L. The within- and between-day CVs were less than 2.5 % and 6.7%, respectively,for all compounds.The lower limitsof detection for 3-methoxy-4-hydroxyphenylgly-col and 3,4-dihydroxyphenylacetic acid were 0.5 pg and for theother three analytes 1.5 pg per injection.Preliminarydata on monoaminergicmetabolitesby the currentassay showed that concentrations of dopaminergic and serotonergic metab