Anodic Stripping with Collection at Interdigitated Carbon Film Microelectrode Arrays

Abstract

Interdigitated arrays of microband electrodes are used for highly sensitive anodic stripping with collection experiments. Compared to analogous experiments at rotating ring-disk electrodes, the interdigitated microelectrode array offers high collection efficiencies and the use of quiescent solutions. New lithographically fabricated carbon band microelectrodes, made by pyrolysis of 3,4,9,10-perylenetetracarboxylic dianhydride, are employed for supporting the mercury film. Metal cations stripped from one microband electrode diffuse across the narrow gap and are redeposited (collected) at the second electrode, kept at a suitable negative potential. The elimination of the charging current (accrued from the fixed collection potential) results in well-defined peaks, superimposed on a constant background, and hence in a greatly improved detectability. Experimental variables affecting the collection efficiency and the response, including the gap and scan rate, are examined.

Microelectrode Arrays and Microfabricated Devices in Electrochemical Stripping Analysis

“…2E). This layout has found limited application in stripping analysis [32]. Due to the characteristics of photolithographic fabrication procedures, all the MEAs fabricated with these techniques are recessed (Fig.…”

“…An alternative fabrication protocol, in this case adopted for interdigitated microelectrode arrays, was proposed by Tabei et al [68] and afterwards applied by Wang et al [32] in the detection of heavy metals. This consisted of the pyrolytic deposition of a thin film of conductive carbon onto a Pt coated Si wafer.…”

“…Several plating solution compositions have been proposed, such as (i) Hg(CH 3 COO) 2 [19]. Several electrode materials have been proposed as possible supporting substrates for the Hg electrode, including Pt [19], diamond-like carbon [26], ITO [70], carbon [32,[65][66][67], rhodium and iridium/rhodium (Ir 0.9 Rh 0.1 ) alloys [40] and Ir [36]. …”

“…Wang et al developed a Hg-coated carbon-based interdigitated array (IDA) for anodic stripping voltammetry with collection (ASVWC) [32]. ASVWC at the IDA consists of performing an anodic stripping voltammetric experiment at one of the electrodes in the array while maintaining the second electrode (the collector) at a constant potential suitable for redeposition of the metal stripped from the first.…”

“…By using an IDA with a small gap (2 to 5 μm), concentrations of Cd and Pb in the low ppb range were detected. A similar approach was also used for the detection of Hg at low ppb levels, in this case using a Au IDA [32].…”