Determination of serum albumin using bromocresol purple as electrochemical probe

An electrochemical quantitative method of protein is developed based on the interaction between bromocresol purple(BP) and proteins. In pH 4.5 Britton-Robinson(B-R) buffer solution, BP has a sensitive reductive peak at -0.518 V(vs. SCE) on the hanging mercury drop electrode. After adding human serum albumin (HSA) to the above solution, the reduction peak current of. BP decreased apparently without the shift of the peak potential. The decrease of the reductive peak current of BP is proportional to HSA concentration in the range of 1.0-20.0 mg/L and 20.0-200. 0 mg/L with the regression equation DeltaI(P)(n)= 90.87 +150-53c(r=0. 997) and DeltaI(P)(n)=3 063. 70+9. 05c(r=0.992), respectively. The binding ratio of HSA with BP is 1 : 2 and the binding constant beta(s) = 1.32 X 10(9). The proposed method was applied to determine the content of HSA in blood samples and the results are in accordance with the traditional Coomassie Brilliant Blue G-250 spectrophotometric assay. This method was further applied to the determination of bovine serum albumin, bovine hemoglobine egg albumin etc. with satisfactory results.