A gas chromatographic method for the determination of antidepressant drugs in human serum

A universal gas chromatographic method for the determination of the most commonly used antidepressant drugs in 1 ml of serum is described. Prior to extraction the samples were washed with hexane at acid pH. After the hexane wash the drugs were extracted into hexane at pH approximately 10, and subsequently reextracted from the hexane into a 1% solution of formic acid in methanol. The methanolic phase was evaporated, the residue dissolved in isopropanol and analysed by gas chromatography with nitrogen detection on a 3% OV-225 column. Recoveries for amitriptyline, nortriptyline, clomipramine, desmethylclomipramine, doxepin, desmethyldoxepin, imipramine, desipramine, maprotiline, protriptyline, trimipramine and desmethyl-trimipramine were found to be 80% or higher. Limits of detection were found to be 5-10 ng/ml for teritary amines and 10-20 ng/ml for secondary amines. Interferences from some common basic drugs were investigated as well as interferences between different antidepressant drugs. Gas chromatographic data are given for 28 drugs and metabolites.