Highly sensitive and selective spectrofluorimetric determination of tolnaftate through the formation of ternary inclusion complex of β-naphthol/β-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 supramolecualr multirecognition interaction among the anionic surfactant sodium laurylsulfate (SLS), β-cyclodextrin (β-CD) and β-naphthol (ROH). The mechanism of the inclusion was studied and discussed by means of fluorescence spectrum, infra-red spectrograms and 1HNMR spectroscopy. Results showed that the naphthalene ring of ROH and the hydrophobic hydrocarbon chain of SLS were included into the β-CD's cavity to form a ROH:SLS:β-CD ternary inclusion complex with stoichiometry of 1:1:1 at room temperature, which provided effective protection for the excited state of ROH. At λex/λem = 273/360 nm, the fluorescence intensity was linear over a tolnaftate concentration range of 2.46 × 10−9 to 2.10 × 10−6 mol L−1. The detection limit and relative standard deviation was 7.50 × 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.