Automated high-resolution gas chromatographic analysis of psychotropic drugs in biological fluids using open-tubular glass capillary columns. I. Determination of nomifensine in human plasma.

An automated high-resolution gas chromatographic method has been developed for the determination of low levels of the antidepressant psychotropic drug Nomifensine in human plasma. The drug is extracted from alkalinized plasma with diethyl ether and then back-extracted into an acidic aqueous phase. After subsequent extraction into diethyl ether the drug is analysed by gas-liquid chromatography as its heptafluorobutyrate derivative using an OV-101 open-tubular glass capillary column with a nitrogen-specific detector. The propyl and butyl analogues of Nomifensine are used as internal standards, added to the plasma before extraction. The method is accurate, specific and precise, and capable of measuring plasma concentrations down to a level of 2 ng/ml. A preliminary study of the pharmacokinetics of the drug, together with steady-state level measurements in normal individuals receiving therapeutic dosages of Nomifensine, has been made.