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
${\rm Zn}^{2+}$
,
${\rm Ni}^{2+}$
ions and a little less for
${\rm Cd}^{2+}$
. The electrode indicates a good linear response for the three metals over a wide concentration range from
$1.0\times 10^{-9}$
to
$1.0\times 10^{-4}\ {\rm M}$
, with a detection limit of
$1.0\times 10^{-9}\ {\rm M}$
.