Sensitive determination of digoxin in tablets by flow injection with fluorescence detection

Abstract

A sensitive flow injection (FI) fluorimetric procedure is described for the determination of digoxin in tablets. The approach is rapid and has resulted in automatable methods for dissolution testing, uniformity of content and bulk assay of a 0.25 mg tablet formulation. Tablet extracts are injected into a single flowing stream of alcoholic hydrochloric acid containing benzoyl peroxide and ascorbic acid. An on-line heating stage facilitates the rapid formation of fluorescent species, which are detected using excitation and emission wavelengths of 364 and 488 nm, respectively. The methods have been fully validated and are linear down to 0.5 µg ml^–1. This approach is also applicable to other digoxin formulations.