Abstract: In Britton-Robinson buffer of pH2.36, the binding reaction of methyl blue with proteins enhances remarkably theresonance Rayleigh light-scattering (RLS) signal at maximum wavelength of 350 nm and forms complexes. It is found that theenhanced RLS intensities are in proportion to the concentrations of protein. Based on this, a new method for the determinationof proteins using methyl blue as indicator has been developed. Bovine serum albumin and human serum albumin could be determinedunder optimum conditions。The linear ranges of the calibration curves were 0～2.4mg/L for human serum albumin and 0～2.8mg/L for bovine serum albumin, and the detection limits were 39.3 and 43.4μg/L, respectively. The method had the advantagesof simplicity and high sensitivity. It has been used to determine total proteins in milk, soybean milk, human serum albumin andhuman urine. The results by this method are consistent with those obtained by the Coomassie brilliant blue G-250 assay。

Key words: methyl blue, lesonance light scatting, protein