Analysis of tricyclic antidepressant drugs by gas chromatography using nitrogen-selective detection with packed and capillary columns.

A gas chromatographic method using either a conventional packed column (3% SP-2250) or a capillary column (SE-30) for the measurement of therapeutic plasma concentrations of tricyclic antidepressant drugs and their demethylated metabolites is described. The technique is based on a simple hexane extraction of drugs from alkalinized plasma followed by derivatization with heptafluorobutyric anhydride for the measurement of demethylated compounds. Subsequently, parent drugs and derivatives are chromatographed and detected using a nitrogen-selective detector. A comparison of the results using both types of chromatographic systems is discussed.