title: Quantitation of trimipramine enantiomers in human serum by enantioselective high-performance liquid chromatography and mixed-mode disc solid-phase extraction.
abstract: A sensitive and stereospecific method for the quantitation of trimipramine enantiomers in human serum was developed. The assay involves the use of a novel mixed-mode disc solid-phase extraction for serum sample clean-up prior to HPLC analysis and is also free of interference from the enantiomers of desmethyltrimipramine, 2-hydroxytrimipramine, and 2-hydroxydesmethyltrimipramine, the three major metabolites of trimipramine. Chromatographic resolution of trimipramine enantiomers was performed on a reversed-phase cellulose-based chiral column (Chiralcel OD-R) under isocratic conditions using a mobile phase consisting of 0.3 M aqueous sodium perchlorate-acetonitrile (58:42, v/v) at a flow-rate of 0.5 ml/min. Recoveries for R- and S-trimipramine enantiomers were in the range of 93-96% at 25-185 ng/ml levels. Intra-day and inter-day precisions calculated as R.S.D. were in the ranges of 0.30-8.00% and 1.60-10.20% for both enantiomers, respectively. Intra-day and inter-day accuracies calculated as percent error were in the 0.01-2.10% and 1.00-3.00% ranges for both enantiomers, respectively. Linear calibration curves were in the concentration range 15-250 ng/ml for each enantiomer in serum. The limit of quantification of each enantiomer was 15 ng/ml. The detection limit for each enantiomer in serum using a UV detector set at 210 nm was 10 ng/ml (S/N=2). In addition, separation of the enantiomers of desmethyltrimipramine, 2-hydroxytrimipramine, and 2-hydroxydesmethyltrimipramine were investigated. The desmethyltrimipramine enantiomers could be resolved on the Chiralcel OD-R column under the same chromatographic conditions as the trimipramine enantiomers, but the other two metabolite enantiomers required different mobile phases on the Chiralcel OD-R column to achieve satisfactory resolution with Rs values of 1.00.
authors.affiliation: Department of Medicinal Chemistry, College of Pharmacy, University of Georgia, Athens, 30602-2352, USA.
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: J T
authors.initials: JT
authors.lastname: Stewart
mesh_terms: D000929:Antidepressive Agents, Tricyclic / Q000097:blood*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006801:Humans; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D014299:Trimipramine / Q000031:analogs & derivatives / Q000097:blood*
chemical_list: D000929:Antidepressive Agents, Tricyclic; C078397:2-hydroxydesmethyltrimipramine; C070661:2-hydroxytrimipramine; D014299:Trimipramine; C040606:desmethyltrimipramine