Room temperature phosphorescence quenching study of coumarins. Indirect determination of warfarin in pharmaceuticals

Room temperature phosphorescence of the 1-bromonaphthalene/β-cyclodextrin/cyclohexane inclusion complex was studied in the presence of coumarins: warfarin, coumarin, dicumarol and umbelliferone. The differences encountered when using right-angle or front-face illumination geometry are shown in order to mark the importance of a correct measurement. Phosphorescence static quenching was observed with the coumarins, as the phosphorescence lifetimes could reveal. Warfarin determination was performed using a commercial anticoagulant making use of the interaction between coumarins and the studied inclusion complex.