QUANTITATIVE-DETERMINATION OF PENTAZOCINE ENANTIOMERS IN HUMAN SERUM USING DERIVATIZED BETA-CYCLODEXTRIN-MODIFIED CAPILLARY ELECTROPHORESISAND SOLID-PHASE EXTRACTION

A high performance capillary electrophoresis (HPCE) assay for the quan titation of (-) and (+) pentazocine in human serum was developed. Reso lution of the pentazocine enantiomers was achieved using 15mM methyl-b eta-cyclodextrin (Me-beta-CD) in 100mM phosphate buffer pH 2.5. A 72cm uncoated fused-silica capillary at a constant voltage of 20kV was use d for the analysis and 0.03mM hexadecyltrimethylammonium bromide (HTAB ) was added to the buffer to decrease the adsorption of endogeneous su bstances onto the silica wall. The analytes of interest were extracted from serum using a solid phase extraction(SPE) procedure. The phenyl SPE cartridge gave good recoveries in excess of 90% for both (-) and ( +) pentazocine, without any interferences. The detection limits were 2 5ng/mL and the limits of quantitation mere 35ng/mL for each enantiomer . The calibration curves were linear over a range 35-400ng/mL with nal orphine as the internal standard, and the coefficients of determinatio n were greater than 0.999 (n=3). Precision and accuracy of the method were in the range 1.4-7.5% and 1.3-4.7%, respectively, for (-) pentazo cine and 1.1-7.8% and 1.4-4.3%, respectively, for (+) pentazocine (n=3 ).