Molecularly Imprinted Polymer-Based Sensors for Amperometric Determination of Nonelectroactive Substances

Amperometric sensors for nonelectroactive substances have been obtained by contacting glassy carbon or graphite electrodes with molecularly imprinted polymeric (MIP) membranes, 300-0.6 mu m thick. The thicker membranes were self standing membranes while the thinner ones were prepared by drop coating on a graphite electrode. Cyanuric acid and atrazine were the target compounds. Determinations were carried out at - 850 mV (vs. Ag/AgCl(sat)) in aqueous solution at pH 1.5, followed by a step at +500. The current linearly depends on the concentration of the template molecule in aqueous solution up to 10(-4) M. For atrazine the current increases with the concentration, while for cyanuric acid the current intensity decreases. Not any current variation was observed on bare carbon electrodes, nor on electrodes covered with a nonimprinted membrane. The detection limit was 9 x 10(-7) M for atrazine and 2 x 10(-5) M for cyanuric acid. The sensors response was very fast and selective for the corresponding template.