Resonance Rayleigh scattering spectra study on the interactions of chito-oligosaccharides with acid blue 119 and their analytical applications

In the weakly citric acid-Na2HPO4 buffer solution, chito-oligosaccharides (COS) interacted with acid blue 119 to form an ion-association complex of COS-acid blue 119, which increased the resonance Rayleigh scattering (RRS) intensities at 349 nm. Moreover, with the addition of Triton X-114 (TX114), the RRS intensities of the system increased and the changes of the intensities were linear to the concentration of COS in the range of 0.125-3.00 mu g/mL with the limit of detection (LOD) of 37 ng/mL. The regression equation was Delta I = 1348.6c + 6.1063 with the correlation coefficient of 0.9984. The experimental conditions were optimized, the effects of the coexisting substances were evaluated and excellent selectivity was exhibited. The reaction mechanism and causes of the RRS intensity enhancement were also discussed. At the same time, the method was demonstrated with the determination of COS in health products with satisfactory results. Therefore, the proposed method was proved as a simple, low cost, high sensitive and selective method.