Anodic coulometric detection with a glassy carbon electrode in combination with reversed-phase high-performance liquid chromatography. Determination of blood levels of perphenazine and fluphenazine.

A detector for liquid chromatography, based on anodic electrochemical oxidation at a glassy carbon electrode, is used in combination with reversed-phase liquid chromatography for the determination of the long-acting tricyclic psychotropic drugs fluphenazine and perphenazine in blood. Completely porous microparticulate silica material, modified so as to give a methyl silica, was used as the stationary phase and buffered mixtures of methanol and water as the mobile phase. The low detection limit and the selectivity of the coulometric detector made possible the determination of concentrations of 1-20 ppb of the compounds of interest. An extraction procedure was in order to obtain sufficient selectivity. Data for the precision, detection limit and yield of the extraction procedure are given. A number of serum levels of perphenazine after oral administration and of fluphenazine after i.m. doses of fluphenazine decanoate are stated.