Computerized Dynamic Voltammetric Detection in High Performance Liquid Chromatography

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Abstract
An automatic and reliable electrochemical detection system is described for on-line qualitative and quantitative determination of electro-active compounds in effluents from high-performance liquid chromatographic systems. Determination is performed by application of electrochemical detection at constant potential, cyclic voltammetry and square-wave voltammetry. In the square-wave mode, the current and time-comparing mode for qualitative compound detection has been discussed. The system has been tested for the identification of etoposide at a glassy-carbon electrode (g.c.e.). Using a static mercury drop electrode (s.m.d.e.), such parameters of the nitro-imidazole derivatives Ro 07-0582, Ro 05-9963, Ro 07-0913 and Ro 03-8799 have been investigated. Applying square-wave voltammetry owns benefits like increased sensitivity and producing peaks at half-wave potential, enabling fast and easy identification of compounds. For square-wave voltammetry of etoposide at de g.c.e., a 10-fold improvement of the detection limit has been achieved with respect to cyclic voltammetry: 10 μ1 2.55E-4 M. Using a s.m.d.e. the detection limit of Ro 05-9963 (desmethylmisonidazole) is 10 μ1 2.67E-5 M.