[Study on determination of protein with Arsenazo I using resonance light scattering technique]

A new RLS (Resonance light scattering) probe is presented in this paper. In the Britton-Robinson buffer at pH 3.29, Arsenazo I combines with proteins by intermolecular forces, resulted in an enhanced Rayleigh light scattering. The RLS intensity reaches maximum at 400 nm and is proportional to the concentration of protein. A novel method for the determination of micro-amount of protein is developed. The assay is simple, rapid and sensitive with a detection limit at 60 ng.mL-1 and a linear range up to 18 micrograms.mL-1. This method is applied to the determination of human serum protein, and the results, compared to Bradford method, is satisfactory. The interaction of Arsenazo I with BSA, gamma-G, oval albumin, lysozyme, pepsin are investigated and the mechanism of RLS is also discussed.