High-performance liquid chromatography determination of praziquantel enantiomers in human serum using a reversed-phase cellulose-based chiral stationary phase and disc solid-phase extraction

A sensitive HPLC method for the quantification of praziquantel enantiomers in human serum is described. The method involves the use of a novel disc solid-phase extraction for sample clean-up prior to HPLC analysis and is also free of interference from trans-4-hydroxypraziquantel, the major metabolite of praziquantel. Chromatographic resolution of the enantiomers was performed on a reversed-phase cellulose-based chiral column (Chiralcel OJ-R) under isocratic conditions using a mobile phase consisting of 0.1 M sodium perchlorate-acetonitrile (66:34, v/v) at a flow-rate of 0.5 ml/min. Recoveries for R-(-)- and S-(+)-praziquantel enantiomers were in the range of 84-89% at 50-500 ng/ml levels. Intra-day and inter-day precisions calculated as R.S.D. were in the ranges of 3-8% and 1-8% for both enantiomers, respectively. Intra-day and inter-day accuracies calculated as percent error were in the 0.2-5% and 0.3-8% ranges for both enantiomers, respectively. Linear calibration curves were in the concentration range 10-600 ng/ml for each enantiomer in serum. The limit of quantification of each enantiomer was 10 ng/ml. The detection limit for each enantiomer in serum using a UV detector set at 210 nm was 5 ng/ml (S/N=2).