Composite Solid Electrodes - Tool for Organic Electrochemistry

The manuscript reviews the recent trends and advances regarding utilization of composite solid materials, above all, of their application for construction of composite solid electrodes (CSEs). These electrodes have been used in electrochemical studies and determinations of micromolar and submicromolar (in some cases even subnanomolar) concentrations of various environmentally important biologically active, mostly organic substances. They have been relatively frequently used in scientific as well as in commercial laboratories for last two decades. The review is focused predominantly on electrodes belonging to the group of composite electrodes with random ensembles of dispersed particles with final solid form. The composite electrode material contains, according to their principal definition, at least one conductor (metal - silver, gold, amalgam etc.), nonmetallic conductor (e.g., graphite powder) or their mixture and at least one insulator (a polymer or a monomer), which are mixed together. Some specific properties, required for determination of chosen analytes in specified matrices, can be reached by addition of proper modifiers into the electrode bulk and/or on the electrode surface, e.g., a catalyst or an enzyme. CSEs can be applied either in batch analyses or in flow liquid systems (especially HPLC or FIA with electrochemical detection). CSEs proved experimentally to be a suitable, reliable, and environmentally friendly substitutes for the hanging mercury drop electrode (HMDE) in electrochemical analyses. The review is focused on the organic applications of CSEs, nevertheless, their utilization in the field of inorganic analysis is mentioned too.