Stereospecific high-performance liquid chromatographic determination of tocainide

Abstract A sensitive high-performance liquid chromatographic assay was developed for the determination of tocainide enantiomers in plasma. Following extraction of tocainide from plasma, the enantiomers were derivatized with S -(+)-1-(1-naphthyl)ethylisocyanate. The resulting diastereomers were separated and quantified using normal-phase chromatography with fluorescence detection set at 220/345 nm (excitation/emission). The peaks, resolved with a resolution factor greater than 1.5, were free from interference. Linearity was established over the concentration range 0.25–10.0 mg/l for each enantiomer in plasma ( r 2 >0.998). The inter-assay variability was less than 10% at all concentrations examined. The method can be used to determine the pharmacokinetics of tocainide enantiomers in man.