Cloud point extraction-fluorimetric combined methodology for the determination of trace warfarin based on the sensitization effect of supramolecule

Compared to the fluorescence spectra of warfarin in pure ethanol and in the presence of the nonionic surfactant Tergitol 15-S-7 after cloud point extraction (CPE), it can be seen that the fluorescence emission peak underwent an obvious red shift and the fluorescence intensity of warfarin was significantly increased in the presence of Tergitol 15-S-7. In order to confirm Tergitol 15-S-7-induced supramolecular effects, the investigations on the fluorescence quantum yields of warfarin in the micellar medium and pure ethanol were performed. The experimental results showed that the supramolecular interactions between Tergitol 15-S-7 and the warfarin excimers played a key role for improving the warfarin fluorescence properties.Based on these facts, a simple fluorometric method combined with CPE for the determination of trace warfarin was developed for the first time. Under optimized experimental conditions, the linear concentration range for warfarin was 3.0×1.0^?9–1.0×10^?6 mol L^?1 and the detection limit was 3.3×10^?10 mol L^?1. And, the proposed method was approved to be appropriate for monitoring warfarin in actual pharmaceutical formulations and biological fluid samples by recovery test, in comparison with other reported methods being satisfactory.