Simultaneous measurement of monoamines, their metabolites and 2,3- and 2,5-dihydroxybenzoates by high-performance liquid chromatography with electrochemical detection. Application to rat brain dialysates.

A reversed-phase chromatographic method with electrochemical detection was developed for the simultaneous determination of 2,3- and 2,5-dihydroxybenzoates, indicators of in vivo hydroxyl free radical formation, monoamines (NE, DA, 5-HT) and their metabolites (MHPG, DOPAC, HVA, 3MT, 5-HIAA). Linearity was observed from 10 pg to 10 ng injected. Reproducibility is correct (C.V. about 9%) except for 3MT and 5-HT. The limit of detection for almost all products was about 20 pg injected on the column. An application of this method in the study of the neurotoxicity of high pressure oxygen in rat is described. The limit of quantification for all compounds was 5 ng/ml except for HVA (10 ng/ml). Some basal levels DA, 5-HT, 5-HIAA, HVA, DOPAC, 3MT, 2,5-DHBA and 2,3-DHBA in microdialysates coming from striatum of normoxic restrained rats are given.