SEPARATION OF DIHYDROXYBENZOATES, INDICATORS OF IN-VIVO HYDROXYL FREE-RADICAL FORMATION, IN THE PRESENCE OF TRANSMITTER AMINES AND SOME METABOLITES IN RODENT BRAIN, USING HIGHPERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

Based on a detailed study of retention parameters, reversed-phase ion- pair chromatographic methods were developed for the simultaneous deter mination of dihydroxybenzoates, indicators of in-vivo hydroxyl free ra dical formation, transmitter amines and some metabolites to facilitate neurochemical investigations in rodent brain. Coupling of the separat ion methods with electrochemical detection and the use of short-chain perfluorinated carboxylic acids for ion-pairing, allowed for a fast an d sensitive determination of salicylate-derived 2,3- and 2,5-dihydroxy benzoic acids and the major electroactive, hydroxylated aromatic compo unds present in brain samples. Detection limits for the dihydroxybenzo ates (signal-to-noise ratio = 2) were 18-22 fmol injected on the colum n. Basal levels of 2,3-dihydroxybenzoate and 2,5-dihydroxybenzoate in the striatum of mice treated with salicylate were 72 +/- 13 and 94 +/- 11 ng/g wet tissue, respectively.