Pre-column derivatization with fluorescamine and high-performance liquid chromatographic analysis of drugs : Application to tocainide

Abstract

The quantitative determination of tocainide, a new antiarrhythmic agent, by high-performance liquid chromatography (HPLC) is reported. The drug and a chemically similar internal standard were extracted from blood plasma with acetonitrile under salting-out conditions obtained by saturation of the aqueous medium with sodium chloride—sodium carbonate. The organic extract, without evaporation, was treated with borate buffer (pH 8.2) and fluorescamine. The resulting derivatives were chromatographed on an ODS reversed-phase column using a methanol—phosphate buffer (pH 7.0) mixture as mobile phase and were detected fluorometrically by monitoring the emission at 485 nm, with excitation at 395 nm. The intra-assay coefficients of variation were 3.0 and 4.3% for ten replicate 0.25 and 1.00 μg/ml samples, respectively, and the inter-assay coefficient of variation was 3.6% for ten replicate 1.00 μg/ml samples. The procedure is simple, rapid, sensitive, and specific. Several other drugs and drug metabolites also were derivatized with fluorescamine and chromatographed successfully. Pre-column derivatization with fluorescamine followed by HPLC with fluorometric detection may have significant advantages in drug analysis.