Detection behavior of phenolic compounds in a dual-electrode system assembled from track-etched membrane electrodes

Electrochemical detection behavior of phenolic compounds in a series dual-electrode detector constructed from track-etched membrane electrodes (TEMEs) was investigated using microbore high-performance liquid chromatography. This detector featured complete electrolysis provided by the electrode structure, which consisted of cylindrical pores with a uniform diameter. The collection efficiency, which was defined as the ratio of peak areas observed at the first and second working electrodes, ranged from negative values up to 1.0. Because it reflected the electrochemical reaction's reversibility and the reaction products' stability, the substance-inherent collection efficiency varied over a much broader range of values than that obtained with conventional electrochemical detectors. The collection efficiencies of catechol and hydroquinone were up to 1.0. Resorcinol produced an anodic peak at both the first and second working electrodes despite a lower potential for polarization of the second electrode than the first electrode. In this case, the collection efficiency was negative. The results showed that the resulting product was oxidized in a low potential region. Catechin compounds, which have both catechol and resorcinol moieties, displayed the characteristics of both catechol and resorcinol simultaneously. Gallic acid, which produced an irreversible cyclic voltammogram, showed a quasi-reversible property produced by a relatively short transition time in the dual-electrode detector. The reported data will be valuable for peak identification and estimation of peak purities in complex chromatograms.