Enantiomeric determination of praziquantel and its main metabolite trans-4-hydroxypraziquantel in human plasma by cyclodextrin-modified micellar electrokinetic chromatography

A capillary electrophoresis method for the simultaneous quantitation of pra ziquanteland its main metabolite trans-4-hydroxypraziquantel enantiomers in human plasma was developed and validated using cyclodextrin-modified micel lar electrokinetic chromatography. Sample clean-up involved a single-step l iquid-liquid extraction of plasma with toluene after the addition of NaCl. The complete enantioselective analysis was obtained in less than 7 min usin g 2% w/v sulfated beta -cyclodextrin as chiral selector and 20 mmol/L sodiu m deoxycholate as surfactant, in 20 mmol/L sodium berate buffer, pH 10. A 5 0 mum x 42 cm uncoated fused-silica capillary was used for the analysis, pe rformed at a voltage of 18 kV and at 20 degreesC. The calibration curves we re linear over the 125-625 ng/mL concentration range. The mean recoveries f or praziquantel and trans-4-hydroxypraziquantel were up to 96 and 71%, resp ectively, with good precision. All four enantiomers were quantified at two concentration levels (200 and 600 ng/mL) with precision and accuracy below 15%. The quantitation limit was 50 ng/mL for (-)-(R)- and (+)-(S)-praziquan tel and 62.5 ng/mL for (-)-(R)- and (+)-(S)-trans-4-hydroxypraziquantel, us ing 1 mt of human plasma.