Study on the interaction between verapamil hydrochloride and eosin Y by absorption, fluorescence and resonance...

In pH 2.8~3.6 HCl-NaAc buffer solution, eosin Y (EY) can react with verapamil hydrochloride(VP) to form a 1:1 ion-association complex, which not only causes the change of absorption spectra and the quenching of fluorescence, but also results in the great enhancement of resonance Rayleigh scattering (RRS). Furthermore, a new RRS spectrum with the maximum wavelength at 324 nm will appear. In this work, the spectral characteristics of absorption, fluorescence and resonance Rayleigh scattering spectra, the optimum conditions for the reaction, the influencing factors and the analytical properties have been investigated. Thereby, a sensitive, simple, rapid and new method for the determination of VP by using eosin Y as a probe has been developed. The detection limit is 0.95 ng/mL for RRS method, 6.4 ng/mL for fluorophotometry and 0.18 μg/mL for spectrophotometric method. The absorbance, RRS and fluorescence intensity is proportional to the concentration of VP in the range of 0.6036~4.0 μg/mL, 0.0032~4.5 μg/mL and 0.0213~4.0 μg/mL, respectively. The effects of the reaction of verapamil hydrochloride and eosin Y on the absorption, fluorescence and resonance Rayleigh scattering spectra have been investigated. Meanwhile, the influences of coexisting substances are tested by RRS method and the results show that this method can be satisfactorily applied to the determination of VP in tablet and human serum samples. The composition and structure of the ion-association complex and the reaction mechanism are discussed. Moreover, the energy transfer among absorption, fluorescence and RRS was investigated briefly in this work.