A polypyrrole-coated, piezoelectric sensor for Cr-VI. Preliminary results

The piezoresonators of a quartz-crystal microbalance mere surface-coated wi th electropolymerised polypyrrole films. After potentiostatic reduction at -0.9 V, the reduced PPy-coated resonators were allowed to react with soluti ons containing different concentrations of Cr-VI. Mass changes of the polym er film, originated by ionic transfer during the oxidation reaction of PPy by hexavalent chromium, produced frequency shifts proportional to the conce ntration of Cr-VI. Also, frequency shifts were obtained by reaction of some antioxidants at oxidised PPy-coated resonators. The observed responses dep end on several experimental parameters.