In 0.0035～0.0045 mol/L H2SO4 solution, proteins such as bovine serum albumin (BSA), human serum albumin (HSA), ovalbumin (OVA) and haemoglobin (HGB) could react with [HgI4]2－ by virtue of electrostatic attraction and hydrophobic force to form ion-association complexes. As a result, the resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) intensities were enhanced greatly and the new scattering spectra appeared. The maximum scattering peak at 390 nm is for RRS, 760 nm for SOS and 390 nm for FDS, respectively. The enhanced RRS, SOS and FDS intensities are directly proportional to the concentrations of proteins. The detection limits for the different proteins are 5.7～15.9 ng/mL for the RRS method, 8.2～15.4 ng/mL for the SOS method and 11.2～22.1 ng/mL for the FDS method, respectively. These methods can be used for the determination of trace amounts of proteins. In this work, the effects of interaction of [HgI4]2－with proteins on RRS, SOS and FDS spectral characteristics, intensities and the optimum conditions have been investigated. Meanwhile, the influences of coexisting substances were tested and the results show that the method exhibits a good selectivity. Based on the above researches, a highly sensitive, simple and rapid method for the determination of trace amounts of proteins by resonance light scattering technique has been developed, which can be applied to the determination of proteins in human urine and serum samples with satisfactory results.

Key words: protein, resonance rayleigh scattering, resonance nonlinear scattering, [HgI4]2－