Pulsed coulometric detection with automatic rejection of background signal in surface-oxide catalyzed anodic detections at gold electrodes in flow-through cells
A variation of Pulsed Coulometric Detection (PCD) is described in which the detection potential is scanned in a cyclic fashion during current integration to achieve automatic and virtual elimination of baseline drift caused by surface roughening and changes in pH. The technique is examined at a Au electrode for flow-injection determination if thiourea which is typical of numerous sulfur compounds whose anodic reactions are catalyzed by formation of surface oxide. The baseline decays quickly to a near-zero equilibrium value following start-up and is unchanged for a pH step of ca. 2 units. The technique is concluded to be compatible with pH-gradient chromatography.