Microdetermination of proteins by Rayleigh light scattering technique with acid green 25

Based on the enhancement of Rayleigh light scattering (RLS) of acid green 25 (Ag25) by proteins, a new quantitative determination method for proteins in aqueous solutions has been developed. This assay is very sensitive (0.136-10.20 μg/ml), rapid (<2 min) and simple (one-step assay and common fluorimeter). Differences between the various proteins can be related to their isoelectric points. There is little or no interference from amino acids, most of the metal ions or complexing agents (e.g. EDTA). Interferences by some metal ions, detergents and salts can be minimized by dilution.