Resonance Rayleigh scattering method for the determination of chitosan using erythrosine B as a probe and PVA as sensitization.

A highly sensitive resonance Rayleigh scattering (RRS) method for the determination of chitosan (CTS) was developed. In the pH 3.8 Britton-Robinson buffer solution, CTS interacted with erythrosine B (Ery B) to form an ion-association complex of [Ery B-CTS] which increased the RRS intensity of the system. With the addition of polyvinyl alcohol (PVA), the RRS intensity was significantly enhanced, and the RRS intensity of the reagent blank(I0) dramatically decreased. The enhanced RRS intensity (ΔI) was linearly proportional to the concentration of chitosan. Taking the medium molecular weight chitosan as the representative, the linear range of the method was 5.0-100.0ng/mL and the detection limit (DL) was 0.47ng/mL. The effect of the molecular weight of CTS on its accurate quantification was studied. Furthermore the dispersion and stability mechanism of PVA was discussed. Accordingly this assay was applied to detect the concentration of CTS in health products with satisfactory results.