Abstract:

In 0.05 mol/L（pH 1.3） HCl medium, SDBS combined with MB to form an ion association complex with the composition ratio of 2∶1 by electrostatic interaction and hydrophobicity effect. As a result, the new spectra of RRS, FDS, and SOS appeared and their intensities were enhanced greatly. The maximum wavelengths of RRS, SOS and FDS were located at 310 nm, 647 nm and 341 nm, and the scattering intensities were proportional to the concentration of MB. These three methods have very high sensitivities, and the detection limits were 1.2 ng/mL for RRS, 1.4 ng/mL for SOS and 1.7 ng/mL for FDS, respectively. At the same time, the methods have better selectivity. Based on the above researches, a new spectral method for the determination of trace amounts of MB has been developed. It can be applied to the determination of MB in human serum with a satisfactory result, and the recoveries are 94.4-103.7%. In this work, the optimum conditions of the reaction and the effects of coexisting substances were investigated. In addition, an AM1 method of quantum chemistry was used for the discussion of the reaction mechanism and the reasons of enhancement of resonance light scattering were discussed.

Key words: dodecyibenzene sulfonic acid sodiumsalt,resonance Rayleigh scattering,secondorder scattering,frequency doubling scattering,determination of methylene blue