Single-Electrode Flow Cell for Electrochemiluminescent Flow Analysis

Flow injection analysis and liquid chromatography are frequently combined with electrochemiluminescence (ECL) for flow analysis. Almost all electrochemistry flow analyses employ traditional three-electrode electrochemical flow cells which have working electrode, counter electrode, and reference electrode; however, it is expensive and difficult to fabricate a traditional three-electrode electrochemical flow cell and inconvenient to renew the electrode. In this study, we have developed a single-electrode flow cell using commercially available conductive polyethylene film as the only electrode through potential differences induced by the electrode resistance for the first time. The single-electrode flow cell features a simple structure, easy renewal of the electrode, and low cost compared to the traditional three-electrode electrochemical flow cells. Taking the typical Ru(bpy)₃²⁺/oxalate ECL system as the analytical model, flow analysis of clinically important oxalate was achieved using single-electrode flow cell. A regression linear equation was obtained over the oxalate concentration ranges from 1 to 200 μM, with a detection limit of 0.92 μM. The single-electrode flow cell is promising for ECL flow analysis.