High-pressure liquid chromatographic analysis of drugs in biological fluids II: determination of an antiarrhythmic drug, tocainide, as its dansyl derivative using a fluorescence detector.

A sensitive and specific method is described for the determination of a new primary aliphatic amine antiarrhythmic drug, tocainide. Tocainide, together with an internal standard, is selectively extracted from plasma or blood and reacted with dansyl chloride. The highly fluorescent dansyl derivatives are separated using high-pressure liquid chromatography and measured using a fluorescence detector. The method can measure therapeutic and subtherapeutic concentrations of the drug (0.1-5.0 microng/ml of plasma) with a standard deviation of less than 2%.