Capillary electrophoresis with UV detection, on-line stacking and off-line dispersive liquid–liquid microextraction for determination of verapamil enantiomers in plasma

Abstract

A rapid, convenient, sensitive and reliable dispersive liquid–liquid microextraction (DLLME) method was coupled with field-amplified sample injection (FASI) in capillary electrophoresis with a diode array detector for the quantification of verapamil enantiomers in human plasma samples. Various parameters affecting the extraction efficiency as well as FASI were optimized. The method performance was studied over the concentration range of 25–350 ng mL⁻¹ for each enantiomer in terms of accuracy (recovery = 92–115%), linearity (coefficients of determination (R²) > 0.99) and repeatability (RSDs% agree within 15%). The method was validated in plasma according to FDA guidelines. This is the first work showing the possibility of the use of DLLME and on-line sample pre-concentration techniques for the analysis of verapamil enantiomers in plasma.