Highly sensitive and selective spectrofluorimetric determination of tolnaftate through the formation of ternary inclusion complex of beta-naphthol/beta-cyclodextrin/anionic surfactant system.

An indirect spectrofluorimetric method with high sensitivity and selectivity was developed for the determination of antifungal drug: tolnaftate (TNF), depending on the supramolecular multi-recognition interaction among the anionic surfactant sodium laurylsulfate (SLS), beta-cyclodextrin (beta-CD) and beta-naphthol (ROH). The mechanism of the inclusion was studied and discussed by means of fluorescence spectrum, infra-red spectrograms and (1)HNMR spectroscopy. Results showed that the naphthalene ring of ROH and the hydrophobic hydrocarbon chain of SLS were included into the beta-CD's cavity to form a ROH:SLS:beta-CD ternary inclusion complex with stoichiometry of 1:1:1 at room temperature, which provided effective protection for the excited state of ROH. At lambda(ex)/lambda(em)=273/360 nm, the fluorescence intensity was linear over a tolnaftate concentration range of 2.46 x 10(-9) to 2.10 x 10(-6)mol L(-1). The detection limit and relative standard deviation was 7.50 x 10(-10)mol L(-1) and 1.4%, respectively. The interference of 31 foreign substances was slight. The proposed method had been successfully applied to the determination of tolnaftate in artificial mixed samples with almost quantitative recovery.