Study of the interaction of protein and dibromomethyl-Arsenazo-Al(III) by Rayleigh lightscattering technique

Based on the weak Rayleigh light scattering (RLS) of the complex of dibromomethyl (DBM)Arsenazo-Al(III) which can be enhanced by the addition of protein in weak acidic solutions, a novel method for the determination of protein concentrations has been proposed by using a commonly used spectrofluorimeter. Four proteins, including bovine serum albumin (BSA), human serum albumin (HSA), lysozyme and egg albumin were tested. The dynamic range, for example HSA is 2.5-50.0µgml-1 and the 10sigma determination limit is 83ngml-1. This method has been applied to the determination of proteins in human serum samples, and the results are very close to those provided by clinical physicians. There is very little interference from amino acids, metal ions and other coexisting compounds. The assay is convenient, rapid, inexpensive and simple.