A resonance Rayleigh scattering method for sensitive detection of chitosan based on supramolecular complex and mechanism study.

A convenient and sensitive resonance Rayleigh scattering (RRS) method for the detection of chitosan (CTS) has been developed via forming Cu-Zn supramolecular complex by complexation reaction, hydrophobic force and electrostatic attraction. The microstructure of the complex was characterized by FT-IR, zeta potential, scanning electron microscope (SEM), UV-vis and RRS. Furthermore, the interaction mechanism among Cu(II), Zn(II), CTS and sodium dodecyl benzene sulfonate (SDBS) was studied. The results revealed that CTS and Cu(II) or Zn(II) formed a supramolecular complex with RRS enhancement in weak acid condition. In the presence of SDBS, the RRS intensity of CTS-Cu(II)-SDBS or CTS-Zn(II)-SDBS was significantly higher than that of the binary system without SDBS at the same CTS concentration. The RRS intensity of CTS-Cu(II)-Zn(II)-SDBS was higher than that of CTS-Cu(II)-SDBS and CTS-Zn(II)-SDBS. The RRS intensity increased linearly with the increase of CTS concentration made it possible to determine CTS quantitatively. In the range extending from 0.10 to 5.00 μg/mL, the equation of linear regression was ΔI=1848.8c-138.3 with a correlation coefficient 0.9996, and the detection limit was estimated to be 37.96 ng/mL. The study was successfully applied for the determination of CTS in health food samples, suggesting its great potential toward CTS analysis.