Therapeutic drug monitoring of 13 antidepressant and five neuroleptic drugs in serum with liquid chromatography-electrospray ionization mass spectrometry

Therapeutic drug monitoring of antipsychotic drugs has become more and more important in recent years, and a wellorganized therapeutic drug monitoring service with fast turnaround times is very important. Therefore, an analytical method coupling highperformance liquid chromatography to mass spectrometry with electrospray ionization in the positive mode was established in our laboratory. Amitriptyline, citalopram, clomipramine (including norclomipramine), desipramine, dibenzepin, doxepin (including nordoxepin), escitalopram, flupentixol, fluphenazine, fluvoxamine, imipramine, nortriptyline, opipramol, pipamperone, reboxetine, thioridazine, trimipramine and zuclopenthixol were separated on a reversedphase C18 column. The mobile phase consisted of acetonitrile and ammonium acetate buffer pH 4. Because of different organic solvents used for the liquidliquid extraction and the different volumes of mobile phases in which the residues were dissolved, four analytical systems had to be applied. Within the run-time of maximal 10 minutes the 13 antidepressant and five neuroleptic drugs were baseline separated on the corresponding masstocharge track. The calibration range of each drug was linear, all betweenday coefficients of variation were below 7% and the recovery rates were between 60 and 103%. Using 1 ml of serum, the lower limits of quantification were between 1.2 and 54 nmol/l for the different drugs and below the therapeutic range for each of the different drugs.