Rapid Determination of Warfarin by Sequential Injection Analysis with Cyclodextrin-Enhanced Fluorescence Detection

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Abstract
A procedure for rapid and reproducible measurement of warfarin is described. This is based on a computer-controlled sequential injection analysis (SIA) system and utilises the phenomenon of enhancement of fluorescence seen when the drug forms inclusion complexes with β-cyclodextrin in aqueous solution. Cyclodextrin and warfarin solutions are sequentially injected and mixed within seconds using the automated system and the fluorescence is then monitored immediately. The calibration curve is linear over the measured concentration range of 0.1 to 1 μg/ml (r2 0.998, n=5) with a limit of detection of 0.02 μg/ml. The measurement is fast with response time of 20 seconds, and is also reproducible with coefficient of variation at 1.5% (n=10) at a concentration of 0.5 μg/ml. Water samples spiked with warfarin were successfully measured using the method.