Editorial [ Hot Topic:Electrochemical Stripping Analysis (Guest Editor: Anastasios Economou) ]

Electrochemical Stripping Analysis has always been the electroanalytical technique of choice for trace and ultra-trace determination of metals and organics. It is based on a preconcentration step of the target analytes on a suitable working electrode followed by a conventional voltammetric or chronopotentiometric scan. Trace metals can be determined at μg L-1 or sub-μg L-1 levels after electrolytic preconcentration while those not amenable to electrolysis can be monitored after adsorptive accumula tion of their complexes with appropriate surface-active ligands. Similarly, numerous organic compounds can be determined at race levels after spontaneous adsorptive preconcentration. Application areas include environmental analysis, clinical and biochemical analysis, food control and industrial monitoring. This volume hosts a number of authoritative reviews on the main advances in Stripping Analysis over the last decade, authored by outstanding scientists in the field of electrochemistry. One major area that has attracted much research is the development of new electrode materials. Mercury electrodes, that have dominated Stripping Analysis since the invention of polarography, are no longer desirable due to the toxicity of mercury and, therefore, new types of alternative more environment-friendly electrodes are sought. The first review by Professor R.G. Compton's group focuses on the utility and the applications of boron-doped diamond (BDD) electrodes in Stripping Analysis. BDD consists of a diamond lattice p-type doped with boron to a level that ensures good conductivity and electrochemical properties. These electrodes offer a wide useful potential window, exhibit low background currents (and therefore low limits of detection), provide good stability and reproducibility while their hard and chemically inert surface is less prone to fouling. A notable additional feature of BDD electrodes is that they can be successfully coupled to ultrasound or microwave radiation for signal enhancement (the review by Professor P. Grundler discusses in detail these techniques). Nanoparticle-modified electrodes are another alternative and are dealt with in the second review by Professor R.G. Compton's group. Nanoparticle-modified electrodes are fabricated by covering the surface of a (usually carbonaceous) substrate with randomly distributed metal (e.g. gold, silver, platinum and bismuth) nanoparticles. The electrodes are characterised by a high effective surface area, catalytic activity, enhanced mass transport properties and reduced cost and can act as disposable sensors in Stripping Analysis. Dr. A. Economou's group review the field of bismuth and bismuth-modified electrodes. Bismuth electrodes have attracted much attention since their introduction in 2000 since they have negligible toxicity and their analytical features are analogous to their mercury counterparts. In addition, the fact that metallic bismuth is solid at room temperature offers wide scope for the fabrication of bismuth-modified sensors. The paper by Professor A. Bobrowski reviews the combination of metal film electrodes with Catalytic Adsorptive Stripping Analysis. This Variant of Adsorptive Stripping Analysis exploits catalytic effects to further enhance the sensitivity, leading to the lowest limits of detection yet obtained by any electroanalytical technique. Replacing the pure liquid mercury electrodes traditionally used in Catalytic Adsorptive Stripping Analysis with solid metal (mercury, bismuth or lead) film electrodes reduces mercury waste and provides more robust sensors. Amalgam and alloy electrodes for environmental analysis is the subject of the review by Professor O. Mikkelsen and his group. Alloy electrodes are made of noble metals (mainly silver) in which a second metal (which possesses a high hydrogen overvoltage, such as mercury or bismuth) is added in small amounts. These electrodes are easy to fabricate and maintain, have a wide cathodic potential window, exhibit low toxicity and can be used for on-site monitoring of trace metals by Stripping Analysis. In their paper, Professor C.M.A. Brett's group present an overview of polymer modified electrodes in Stripping Analysis. These electrodes are prepared by modifying the surface of a solid electrode with an ion-exchange, size-exclusion or conductive polymer film. The main utility of such coatings is to improve the selectivity of the determination by preventing fouling of the electrode surface by surface-active macromeolecules. However, polymeric coatings may additionally improve the sensitivity and long-term stability of the underlying electrodes. The general trend towards miniaturization has also affected research in Stripping Analysis. Microlectrodes, nanoelectrodes and arrays of microelectrodes are comprehensively reviewed in the papers authored by the teams of Professor S. Daniele and Dr. D. Arrigan.