Microdetermination of proteins with the arsenazo-DBN-Al(III) complex by Rayleigh light-scattering technique and application of the method.

The determination of proteins with arsenazo-DBN and Al3+ by Rayleigh light-scattering (RLS) is described. The weak RLS of arsenazo-DBN and BSA can be enhanced greatly by addition of Al3+ in the pH range 5.3-7.0; this resulted in two enhanced RLS signals at 420-440 nm and 460-480 nm. The reaction between arsenazo-DBN, Al3+, and proteins was studied and a new method was developed for quantitative determination of proteins. This method is very sensitive (0.34-41.71 microg mL(-1) for bovine serum albumin, BSA, and 0.29-53.41 microg mL(-1) for human serum albumin, HSA), rapid (< 2 min), simple (one step), and tolerant of most interfering substances. The effects of different surfactants were also examined. When these proteins were determined in four human serum samples the maximum relative error was not more than 2% and the recovery was between 97 and 103%.