The sensitive chitosan (CTS) detection methods based on the resonance Rayleigh scattering (RRS) quenching method and fluorescence quenching of Eosin Y were put forward. In the HAC-NaAC buffer solution, Eosin Y interacted with Triton X-100 to generate the binary complex which served as the RRS spectral probe. When CTS was interacted with the binary complex, the RRS intensity decreased with the increase of CTS. At the same time, the fluorescence intensity of Eosin Y decreased in the presence of Triton X-100, and the fluorescence intensity of "Eosin Y+Triton X-100" system further decreased when CTS was added. So it was further proved that there was a forming complex in "Eosin Y+Triton X100+CTS" system. The interaction was characterized by zeta potential, RRS, fluorescence spectrum, and UV-Vis spectroscopy. Under optimal conditions, there was a good linear relationship between the RRS decreased intensity (ΔI) and the concentration of CTS in the range of 0.05-1.30 μg/mL, with a regression equation of ΔI = 1325c + 73.66 and correlation coefficient (R2) of 0.9907. The detection limit was 0.0777 μg/mL. Likewise, the linear range of the fluorescence quenching was 0.03-1.30 μg/mL; the regression equation was ΔF = 1926c + 294.0 with R2 = 0.9800 under fluorescence quenching. The detection limit was 0.0601 μg/mL. Therefore, the dual-channel sensor for the determination of CTS was applied to the health products, and the results were satisfactory. The t test result showed that there was no statistical difference between the two methods.
Keywords: Chitosan; Eosin Y; Fluorescence quenching; Resonance Rayleigh scattering quenching method.