Linear sweep voltammetric determination of protein based on its interaction with Alizarin Red S

In this paper, the electrochemical behavior of the interaction of Alizarin Red S (ARS) with bovine serum albumin (BSA) was investigated on the hanging mercury drop electrode (HMDE). In the acidic solution (pH 4.2), ARS can be easily reduced on the HMDE and it has a well-defined polarographic wave at −0.29 V (SCE). On addition of BSA or human serum albumin (HAS) into the ARS solution, the reduction peak current of ARS decreases without the movement of the peak potential and the appearance of new peaks. The study shows that a new electrochemically non-active complex is formed via intercalation of ARS with BSA or HSA, which can not be reduced on the Hg electrode. The decrease of reductive peak current of ARS is proportional to BSA and HSA concentration in the range of 2.0–60 and 2.0–40 mg l−1, respectively. The detection limit of BSA and HSA is 1.0-mg l−1. The analytical results of human serum and urine samples by this method were in good agreement with the Coomassie brilliant blue G-250 assay. The binding number and the binding interaction mechanism are also discussed.