A polypyrrole-coated, piezoelectric sensor for CrVI. Preliminary results

Abstract

The piezoresonators of a quartz-crystal microbalance were surface-coated with electropolymerised polypyrrole films. After potentiostatic reduction at –0.9 V, the reduced PPy-coated resonators were allowed to react with solutions containing different concentrations of CrVI. Mass changes of the polymer film, originated by ionic transfer during the oxidation reaction of PPy by hexavalent chromium, produced frequency shifts proportional to the concentration of CrVI. Also, frequency shifts were obtained by reaction of some antioxidants at oxidised PPy-coated resonators. The observed responses depend on several experimental parameters.