| Recently, resonance light scattering (RLS) technique has been extensively and successfully utilized in various fields because of its simple manipulation, high sensitivity and convenient experimental conditions. For example, RLS technique has been applied to the characterization of supermolecular assemblies, the research of interaction of dye and biomacromolecule such as protein, nucleic acid. RLS technique has become a powerful and routine assay method in analytical chemistry area.A new resonance light scattering method for the determination of trace proteins was developed. The interaction of HSA with SDS and rhodamine B is characterized by the enhanced RLS spectra. At pH 4.35, the RLS intensities of SDS are weak, and it increases when added protein, the RLS intensities increase greatly when added rhodamine B. Atλ= 332.0 nm, the RLS intensities achieves its maximum, and it is found that the enhanced RLS intensities are in proportion to the concentrations of HSA with the limit of determination of 1.9ng/mL. The present method is successfully applied to the determination of human blood plasma samples with the recovery of 94.0%～105.5%.The interaction of sodium dodecylsulfonate (SDS) and cationic dyes (Methylene blue, Azure A, and Azure B) with proteins was characterized by enhanced resonance light scattering (RLS) measurements using a common spectrofluorometer. At pH 4.10, the RLS intensity of SDS is weak, and it can be enhanced a little when protein is presented, but the RLS intensity increased obviously by adding a sort of cationic dye. It was found that the enhanced RLS intensities were in proportion to the concentrations of proteins. From this result, we can assume that when pH is under the isoelectric points (pI0) of HSA (pI0 = 4.7-4.9), HSA shows positive charges, it can bind with SDS via electrostatic attraction and form dualistic complex, and then, the cationic dyes can interact with HSA-SDS and form a triple complex, leading to the formation of much bigger particles. Therefore, the RLS intensities greatly increase. The present method is successfully applied to determine total proteins in human serum samples with the recovery of 93.0%～104.0%.In the alkaline condition, the interaction of barbital with copper-pyridine was characterized by the enhanced resonance light scattering (RLS) signals from 300.0-700.0 nm. In the optimal interaction condition, it was found that the enhanced RLS intensities were in proportion to the concentrations of barbital with the limit of determination of 4.3μg/L. The present method was successfully applied to the determination of barbital sodium in synthetic samples with the recovery of95.7%～103.5%. |
