Capillary electrophoresis of baclofen with argon-ion laser-induced fluorescence detection

A capillary electrophoretic method with laser-induced fluorescence detection for baclofen (4-amino-3-p-chlorophenylbutyric acid) has been developed. 6-Carboxyfluorescein succinimidyl ester was used for precolumn derivatization of the non-fluorescent drug. Optimal separation and detection were obtained with an electrophoretic buffer of 50 mM sodium borate (pH 9.5) and an air-cooled argon-ion laser (excitation at 488 nm, emission at 520 nm). Linearity (rgreater than or equal to0.99) over three orders of magnitude was generally obtained and the lowest derivatizable concentration limit for baclofen in aqueous solution was 10 nM (2 ng baclofen/ml). Coupled with a simple clean up procedure, the method can be applied to the analysis of baclofen in human plasma at micromolar level. Recovery of spiked baclofen in plasma was 95%. The relative standard deviation values on peak size (0.5 muM level) and migration time were 8.2 and 1.0% (n=7), respectively. The limit of detection of baclofen in plasma was 0.1 muM (21 ng/ml). (C) 2002 Elsevier Science B.V. All rights reserved.