Determination of vigabatrin in plasma by reversed-phase high-performance liquid chromatography

A method is described for the determination of vigabatrin in 50 microliters of plasma by isocratic high-performance liquid chromatography using fluorescence detection. The procedure involves protein precipitation with methanol followed by precolumn derivatisation with o-phthaldialdehyde reagent. Separation of the derivatised vigabatrin was achieved on a Microsorb C18 column using a mobile phase of 10 mM orthophosphoric acid:acetonitrile:methanol (6:3:1) at a flow rate of 2.0 ml/min. Assay time is 15 min and chromatograms show no interference from commonly coadministered anticonvulsant drugs. The total analytical error within the range of 0.85-85 micrograms/ml was found to be 7.6% with the within-replicates error of 2.76%. The minimum detection limit was 0.08 micrograms/ml and the minimum quantitation limit was 0.54 micrograms/ml.