Microwave Activated Voltammetry: The Thermally Enhanced Anodic Stripping Detection of Cadmium

Abstract

In situ microwave activation of electrochemical processes in a novel electrochemical cell, in which intense microwave radiation is focused locally into the region at the electrode surface±solution interface, is shown to allow high-temperature voltammetry experiments at 100 mm Pt disk electrodes. Factors such as the cell geometry and the deposition of a thin ®lm of mercury are shown to in¯uence the microwave effect. The detection of trace metals or impurities by anodic stripping voltammetry is a routinely applied procedure with applications especially in rapid online monitoring, in remote place analysis, or for extremely dilute samples. For cadmium detection by anodic stripping voltammetry microwave radiation is demonstrated to strongly affect the accumulation process but not the stripping process. Calibration of the effects induced by microwave radiation on the experimentally observed voltammetric data, based on the equilibrium potentials for the FeCN 4Àa3À 6 and the RuNH 3 3a2 6 redox systems, demonstrates that the data obtained are consistent with a thermally enhanced process. The temperature achievable at the electrode±solution interface before boiling and cavitation occurs, is shown to be strongly dependent on the type of electrode material and surface morphology. At a mercury ®lm electrode deposited on platinum temperatures in excess of 150C can be applied in voltammetric experiments in a constant heating mode.

Microwave-enhanced voltammetric detection of copper(II) at gold nanoparticles-modified platinum microelectrodes

“…It has been shown that current enhancement was strongly dependent on the type of electrode material and surface morphology in microwave field [7]. Most studies to date explored the microwave effect at bare platinum electrodes [8][9][10][11][12]. The properties of carbon and boron-doped diamond electrodes in the microwave field have also been reported [13][14][15].…”

“…The effect of the cell fill height and electrode position were found to be crucial and optimized by maximizing the electrochemically detected thermal effect. The cell and electrode geometry have a considerable effect on the intensity of the microwave radiation focused into the region close to the electrode surface [10].…”

Miniaturization of electroanalytical systems

“…Promising studies on the electrochemical analysis of nucleic acids by the use of heated electrodes have opened a particularly interesting field of application [4]. Recent work by other groups [5,6] stimulated the search for alternative experimental strategies for thermal activation of microelectrodes.…”

Microwave enhanced electrochemistry: mass transport effects and steady state voltammetry in the sub-millisecond time domain

“…doi:10.1016/j.jelechem.2004.06.032 self-focused into a region within the diffusion layer at the electrode surface|solution (electrolyte) interface [11,20]. By acting as an ÔantennaÕ, the metal working electrode is considerably enhancing the microwave effect directly in the vicinity of the electrode surface.…”