Determination of several psychiatric drugs in whole blood using capillary gas-liquid chromatography with nitrogen phosphorus detection:: comparison of two solid phase extraction procedures

A simple and reliable gas chromatographic method with nitrogen-phosphorus detection without derivatization was developed for the detection of several psychiatric drugs in whole blood as part of systematic toxicological analyses (STA). Drugs included mirtazapine, chlorpromazine, methotrimeprazine (levomepromazine), clothiapine, olanzapine, clozapine, haloperidol, and thioridazine. All drugs were studied at concentrations of 100-2000 mu g/L, except haloperidol that was studied at concentrations of 400-8000 mu g/L. In order to select the best blood purification procedure and therefore increase the signal to noise ratio we have compared two solid-phase extraction (SPE) columns, Chem Elut and Bond Elut Certify, for their recovery, precision, sensitivity and matrix purification efficiency. Recoveries for these drugs using Chem Elut columns at 500 and 2000 mu g/L (2000 and 8000 mu g/L for haloperidol) were in the range 21-65%, with intra-assay and inter-assay precisions of less than 17% and 19%, respectively. Limits of detection (LODs) and limits of quantitation (LOQs) for mirtazapine, chlorpromazine, methotrimeprazine, clothiapine, olanzapine, clozapine, and thioridazine ranged from 62 to 161 mu g/L and from 205 to 531 mu g/L, respectively. LOD and LOQ for haloperidol were 442 and 1458 mu g/L, respectively. Recoveries of these compounds using Bond Elut Certify columns at 500 and 2000 mu g/L (2000 and 8000 mu g/L for haloperidol) were in the range 44-97%, with intra-assay and inter-assay precisions of less than 7% and 14%, respectively. LODs and LOQs for mirtazapine, chlorpromazine, methotrimeprazine, clothiapine, olanzapine, clozapine, and thioridazine ranged from 37 to 66 mu g/L and from 122 to 218 mu g/L, respectively. LOD and LOQ for haloperidol were 156 and 515 mu g/L, respectively. Linearity was observed in the studied range for all compounds with r(2) values of > 0.999. The use of the mixed-mode bonded-silica Bond Elut Certify columns showed advantages comparing with Chem Elut columns for the screening of these psychotropic agents such as higher recoveries, cleaner extracts, better sensitivity, better precision and less solvent consumption and subsequent disposal. (c) 2004 Elsevier Ireland Ltd. All rights reserved.