Quantitative analysis for tricyclic antidepressant drugs in plasma or serum by gas chromatography-chemical-ionization mass spectrometry.

We describe a gas chromatographic-chemical-ionization mass spectrometric procedure for determining concentrations of the tricyclic antidepressant drugs and their demethylated metabolites in plasma. The procedure requires 2.0 mL of plasma or serum and involves internal standard addition, extraction with a mixed organic solvent, and separation on a column packed with 0.5% potassium hydroxide and 2% Carbowax 20M. Between-assay and within-assay (n = 10) CVs were less than 11.0%. The procedure has been applied to several interesting cases, three of which are summarized.