A sensitive and specific method for the determination of chlorimipramine and desmethylchlorimipramine in plasma using selected ion monitoring with chemical ionization.

Chlorimipramine and other tricyclic antidepressant drugs are widely used for the treatment of depressive disorders. We analysed chlorimipramine and its major metabolite desmethylchlorimipramine after a two step extraction from plasma with diethylether. The underivatized samples were separated on a short (40 cm x 2 mm) silanized glass column packed with 3% OV 17 on Chromosorb HPW-DMCS, 80-100 mesh, which was directly coupled to the mass spectrometer. Detection of the tricyclic antidepressant drugs and their respective deuterium labelled internal standards was performed by chemical ionization using methanol vapour as reactant gas. The method is simple and sufficiently sensitive to permit the routine analysis of therapeutic plasma levels of tricyclic antidepressant drugs in extracts originating from 1 ml plasma.