Resonance light scattering technique for the determination of proteins with resorcinol yellow and OP

A new resonance light scattering (RLS) assay of proteins is presented. In the citric acid–NaOH (pH 2.35) buffer, the RLS of Resorcinol yellow (RY)–protein system can be greatly enhanced by addition of nonionic surfactant OP, owing to the interaction between OP and RY–protein. The enhanced RLS is in proportion to the concentration of proteins in the range 0.02–4.0 μg ml−1 for both bovine serum albumin (BSA) and bovine hemoglobin (HEM), the detection limits were 10.4 ng ml−1 (S/N=3) for BSA and 11.4 ng ml−1 (S/N=3) for HEM. Samples were determined satisfactorily.