CHEMICALLY MODIFIED ELECTRODES IN LIQUID-CHROMATOGRAPHY DETECTION - A REVIEW

Recent trends in the use of chemically modified electrodes (CMEs) in electrochemical detection systems used in flow-injection analysis or high-performance liquid chromatography are reviewed, with the objective of indicating the most promising approaches for practical CME applications. Four specific application areas of CMEs are identified: (1) those using perm-selective coatings to enhance selectivity and inhibit surface fouling, (2) those using immobilized electron-transfer mediators to catalyse slow electrode reactions, (3) those using enzymes as modifiers to provide biological activity on the electrode surface and (4) those using ion-exchange coatings for the electrochemical detection of non-electroactive anions and cations. By virtue of these approaches, the judicious use of CMEs has already had a significant impact on the performance and scope of electrochemical detection in flow systems. The most important improvements have been in CME selectivity, which produces simpler assay procedures with less need for sample treatment, and increased usefulness for complex samples, and in CME reactivity, which expands the range of analytes amenable to electrochemical monitoring.