[Determination of dextran sulfate sodium with ethyl violet by resonance Rayleigh scattering]

In the Britton Robinson buffer medium (pH 9.0-10.5), either dextran sulfate sodium (DSS) or ethyl violet (EV) showed very faint resonance Rayleigh scattering (RRS) spectra. However, when DSS and EV were mixed together, the interaction between DSS and EV by virtue of electrostatic and hydrophobic forces occurred, which greatly enhanced the RRS intensity and a new RRS spectrum for the DSS-EV system appeared with three obvious scattering wavelengths at 348.0, 509.8 and 680.0 nm, respectively. All these RRS peaks increased with the increase in DSS concentration. The maximum scattering wavelength appeared at 509.8 nm; and therefore was selected as the determination wavelength for the system. The RRS intensity was directly proportional to the concentration of DSS in the range of 0.005-2.4 microg x mL(-1), and the detection limit was 3.25 ng x mL(-1). The characteristics of RRS and absorption spectra of the DSS-EV system, the influencing factors, such as solution pH, EV concentration, reaction time, temperature, and ion strength, and the optimum conditions for the reaction were investigated. The influence of foreign substances on the DSS-EV system was also studied. The method was sensitive and selective, and has been applied to the determination of DSS in synthetic samples with satisfactory results. A new method for the determination of trace amounts of DSS based on the RRS method has been developed.