Selective electrochemical detection using a split disk array electrode in a thin-layer radial flow system

An eight-sector array (split disk) electrode was designed for a low flow rate (<100 μL/min) amperometric detector. This electrode was fabricated photolithographically for dimensional accuracy and reproducibility. This array of a pie-shaped electrode was combined with a thin-layer radial flow cell, and a conversion efficiency of 94% was achieved at the lowest flow rate tested (0.01 mL/min). Each electrode worked free from the effects of electrochemical reactions of the other electrodes. A coulometric hydrodynamic voltammogram of reversible redox species obtained using this system exhibited a Nernstian curve. These properties enabled this electrochemical detector to be used for determining the ratio of two redox species (redox potential difference ≈ 100 mV) with small injection volume (5 μL).