Determination of vigabatrin in human plasma by means of capillary electrophoresis with laser-induced fluorescence detection

A method has been developed for the quantitation of the antiepileptic drug vigabatrin in human plasma. It is based on capillary electrophoresis with laser-induced fluorescence (LIF) detection. The effect of the pH of the buffer and of N-methylglucamine addition to the background electrolyte constituent was investigated. The final background electrolyte consisted of 50 mM borate buffer, pH 9.0, with 100 mM N-methylglucamine and enabled separation within 12 min at 20 kV voltage. A solid phase extraction procedure was used for pre-treatment of biological samples, based on mixed-mode lipophilic – cation exchange cartridges, followed by a derivatisation step with 6-carboxyfluorescein-N-succinimidyl ester. Fluorescence was excited by an Ar-Ion laser (excitation wavelength = 488 nm). Linearity was observed in the 10-120 ng mL-1 plasma concentration range. Extraction yield was >96%, precision (expressed as RSD) was <6.7%, accuracy (recovery) was between 97.0 and 101.6%. The method has been successfully applied to the analysis of vigabatrin in plasma of epileptic patients undergoing therapy with the drug.