SDS could be spontaneously adsorbed on the CPE surface and formed a bilayer through hydrophobic interactions between the hydrophobic long chain of SDS
molecules and the paraffin oil in the carbon paste and sulfate terminal group oriented outside. The adsorbed SDS organized in a dense monolayer on surface would accumulate BPR by electrostatic interaction between positively charged BPR and negatively-charged sulfate group of SDS. Consequently BPR's concentration increases on the electrode surface. However, SDS can improve the electrochemical process of BPR and significantly increase the oxidation peak current.