Spectrophotometric determination of proteins by using nitrosulfophenol C

In this paper, it is found firstly that the nitrosulfophenol C can react wi th proteins to form a pure blue complex in Britton-Robinson buffer solution at pH 3.4 and room temperature, which gives maximum absorption peak at 675 nm with 100 nm to red shift compared to that of nitrosulfophenol C, Accord ing to studies on optimum conditions, a new spectrophotometric method for d etermination of proteins was established, The standard working curves of ei ght kinds of proteins with larger linear ranges and higher sensitivity were determined. The new method was successfully applied to the determination o f protein in human serum samples with satisfactory results in agreement wit h those of the classical coomassie brilliant blue G-250 (CBB G-250) method.