A High Sensitivity Impedimetric Biosensor Using the Tannin From Quercusmacrolepis as Biorecognition Element for Heavy Metals Detection

A new poly(vinylchloride) (PVC) membrane electrode based on tannin from the bark of Quercusmacrolepis (acorn) as the ionophore was prepared and modified onto the surface of a gold electrode. The electrochemical impedance spectroscopy (EIS) technique was used to study the sensitivity of the electrode that was modified with a thin layer of polymeric biomembrane, in order to detect heavy metals ions in solution. The device shows a good sensitivity for Zn²⁺, Ni²⁺ ions and a little less for Cd²⁺. The electrode indicates a good linear response for the three metals over a wide concentration range from 1.0×10^-9 to 1.0×10^-4 M, with a detection limit of 1.0×10^-9 M.