NEW ANTIOXIDANT MIXTURE FOR LONG-TERM STABILITY OF SEROTONIN, DOPAMINE AND THEIR METABOLITES IN AUTOMATED MICROBORE LIQUID-CHROMATOGRAPHY WITH DUAL ELECTROCHEMICAL DETECTION

An automated microbore liquid chromatographic assay with dual electroc hemical detection is described for the determination of serotonin, dop amine and their metabolites, 5-hydroxyindoleacetic acid, 3,4-dihydroxy phenylacetic acid and homovanillic acid, Due to the chemical instabili ty of the compounds, the addition of an antioxidant is required for au tomated analysis over a long period of time (e.g., 20 h). Therefore, t he time stability of these substances was tested with different antiox idants. The stability for serotonin and 5-hydroxyindoleacetic acid was poor in acidic medium containing Na(2)EDTA but could greatly be impro ved by the addition of L-cysteine and ascorbic acid. Using this assay, the neurotransmitters and their metabolites could easily be determine d in microdialysates obtained from different rat brain areas. (C) 1997 Elsevier Science B.V.