Surface ionization organic mass spectrometry of imipramine, desipramine, clomipramine, and lidocaine.

Surface ionization organic mass spectrometry (SIOMS) has been performed on some clinically important drugs (imipramine, desipramine, clomipramine, lidocaine) by using quadrupole mass spectroscopy in which the thermal ion source has a rhenium oxide emitter. The mass spectra were presented, interpreted in a purely empirical way, by means of evidence from previous investigations, and then compared to conventional EI techniques. Sensitivity and selectivity have also been studied, demonstrating that (a) these drug compounds are efficiently surface-ionized, (b) experimental results rationalize the high sensitivity of the surface ionization detector (SID) of gas chromatography (GC) for the examined drugs, and (c) the GC/SIOMS coupling can be used for sensitive and selective detection of the drugs in the serum. An approach to detection of these drugs in serum by GC/SIOMS and GC with SID is described. The characteristics of both methods provide a reliable, sensitive, and selective method, which is needed for low concentration level measurements in complex mixtures.