ENANTIOSELECTIVE DETERMINATION OF R(+) AND S(−) ROGLETIMIDE IN SERUM USING ALPHA-CYCLODEXTRIN MODIFIED CAPILLARY ELECTROPHORESIS AND SOLID PHASE EXTRACTION

Abstract

A capillary electrophoresis (CE) method for the quantitative determination of R(+) and S(−) rogletimide in serum was developed. Stereoselective resolution of the rogletimide enantiomers was achieved using 60 mM alpha-cyclodextrin (α-CD) in 10 mM sodium dihydrogen phosphate/5 mM sodium tetraborate buffer of pH 2.5. A 72 cm uncoated fused-silica capillary at a constant voltage 15kV was used for the analysis and 0.03 mM hexadecyltrimethyl ammonium bromide (HTAB) was added to the buffer to decrease the adsorption of endogenous substances onto the silica wall. The analytes of interest were extracted from serum using a solid phase extraction (SPE) procedure. An octadecyl cartridge gave good recoveries in excess of 85% for both R(+) and S(−) rogletimide without any interference. The detection limits were 50 ng/mL using 1 mL serum and the limit of quantitation were 100 ng/mL for each enantiomers. The calibration curves were linear over the range of 100–1200 ng/mL with S(−) aminoglutethimide as the internal standard and the coefficient of determination was greater than 0.999 (n=3). Precision and accuracy of the method were in the range 2.3–6.7% and 2.2–7.4%, respectively, for R(+) rogletimide and 1.7–6.4% and 1.8–6.6%, respectively, for S(−) rogletimide. The CE method was compared to an existing HPLC method in terms of sensitivity and selectivity for the routine analysis of the drugs.