Spectrophotometric Method for the Determination of Proteins with Aluminum-Chrome Azurol S-Triton X-100 Complex

In pH 3.0-4.3 weak acid medium, aluminum-chrome azurol S-Triton X-100 Complex reacts rapidly with proteins to form complexes, which causes the change of absorption spectra, the increase of absorbance near 220 nm and 636 nm, and all ΔA(=A_0-A) values are proportional to the concentration of proteins, Beer's law is obeyed in the range between 0-50 mg/L or 10-80 mg/L for the different proteins. Their molar absorptivities of reactions are 4.23×10~5-2.01×10~6(near 220 nm) and 2.64×10~5-1.64×10~6(near 636 nm) seperately. Based on these, we developed a new spectrophotometric method for the determination of proteins. The method is simple, rapid, and of good selectivity, and has been used for the determination of total amounts of proteins in human serum and urine samples with satisfactory results.