Abstract

A method for the identification, differentiation and quantification of the following tricyclic antidepressants in human serum is described: amitriptyline, amitriptyline-oxide, clomipramine, desimipramine, dibenzepine, dosulepine, doxepin, lofepramine, imipramine, maprotiline, mianserine, nordoxepin, nortriptyline, opipramol, trimipramine. Serum was extracted with a modified commercial extraction kit and analyzed by computerized gas chromatography - mass spectrometry (GC-MS). On-line computer analysis allowed rapid detection and identification in the SCAN mode. Using the SIM mode (Specified Ions Monitoring) a high analytical sensitivity below the therapeutic range and a recovery above 90% were obtained. Qualitative comparison of the GC-MS procedure with that of the immunoassay resulted in high agreement with only two false negative and one false positive result of the immunoassay. In addition, quantitative defermination of spiked serum samples showed a correlation r² = 0.9813 between both methods. A new mass spectra library was created to support the identification of tricyclic antidepressants in human serum. The GC-MS method presented here for the first time permits the measuring of tricyclic antidepressants with only one internal standard by using 5 individual masses for identifïcation. This allows a highly valid identiflrcation of these compounds combined with sufficient analytical sensitivity. Therefore our method seems useful for the determination of tricylic drugs as easily as by HPLC methods, but with higher analytical sensitivity and specificity.

DOI: Clin. Lab. 1999;45:191-200