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

The piezoresonators of a quartz-crystal microbalance mere 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 Cr-VI. 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 Cr-VI. Also, frequency shifts were obtained by reaction of some antioxidants at oxidised PPy-coated resonators. The observed responses depend on several experimental parameters.