AN IMPROVED HOLDER FOR THE ELECTROCHEMICAL QUARTZ CRYSTAL MICROBALANCE AND ITS CYCLIC VOLTAMMETRY CHARACTERISTICS

The design and characteristics of a stationary, compact holder for an electrochemical quartz crystal microbalance (EQCM) are presented. A Au/quartz crystal oscillator is vertically mounted in a polytetrafluoroethylene body of the holder. The crystal is sealed with an O-ring and is easily accessible for change. The performance of the holder was tested under cyclic voltammetry (CV) conditions with the Ag+/Ag and Cu+/Cu electrodeposition/electrodissolution processes. Frequency changes due to mass changes of the Au/quartz electrode were correlated with CV parameters. The holder was calibrated for a 5 MHz crystal oscillator by means of CV anodic stripping of silver. The mass sensitivity was 19.5 +/- 0.1 ng Hz-1 cm-2. The concentration sensitivity was 14.2 +/- 0.2 muM Hz-1 cm-2 at a potential scan rate of 0.01 V s-1 and 23.7 +/- 0.3 muM Hz-1 cm-2 at a scan rate of 0.02 V s-1 for a potential of scan reversal which was 250 mV more negative than the electrodeposition peak potential.