Abstract:

In a pH 2.5~4.0 Britton-Robinson(BR) buffer medium, some proteins such as bovine serum albumin(BSA), Chymotrypsin(Chy) and α-amylase(α-Amy) can react with chondroitin sulfate A(CS) via electrostatic force, hydrogen bond force or/and hydrophobic force to form binding products. As a result, the resonance Rayleigh scattering(RRS), secondorder scattering(SOS) and frequency doubling scattering(FDS) were enhanced greatly with new scattering spectra appeared. The increments of scattering intensity(ΔI) were proportional to the concentration of CS in certain ranges. The detection limits(3σ) of CS in Chy, BSA and α-Amy systems were 1.4, 2.0 and 1.8 μg/L(RRS method), 2.3, 2.9 and 2.5 μg/L(SOS method), 5.8,13.2 and 9.6 μg/L(FDS method), respectively. Among them, the RRS method exhibited the highest sensitivity and the Chy-CS system was more sensitive than others. The characteristics of the spectra and optimal conditions of RRS method were investigated. The effects of external substances were tested. The established methods have a good selectivity and can be applied to the determination of CS in eye drops with satisfactory results.

Key words: proteins, chondroitin sulfate A, resonance Rayleigh scattering, second-order scattering, frequency doubling scattering