Resonance Rayleigh method for the determination of proteins with Orange G

In pH 0.6 - 2.0 HCl-sodium acetate buffer solution, proteins react with an acidic monoazo dye such as Orange G, Methyl Orange, Methyl Red and Orange I V to form a combination product. This results in a significant enhancement of resonance Rayleigh scattering (RRS) and a new RRS spectrum appears. Owin g to the fact that Orange G-protein system is the most sensitive, it was ta ken as an example to study. The RRS spectral characteristics of its combina tion product and the optimum condition for the reaction were investigated. The intensity of RRS is directly proportional to the concentration of prote in in the range of 0 - 5.0 mug/mL. The method has high sensitivity; its det ection limits are 2.6 ng/mL for BSA, 3.4 ng/mL for HAS and 7.1 ng/mL for al pha -chymotrypsin, respectively. A new method for the determination of trac e amounts of proteins on the basis of RRS spectra has been developed.