Waveform optimization for integrated square-wave detection of biogenic amines following their liquid chromatographic separation Original Research Article

Results are described from research designed to optimize the potential–time (E–t) waveform applied in integrated square-wave detection (ISWD). More specifically, goals of this study included the minimization of background signal with maximization of the signal-to-background ratio (S/B) for application of ISWD to polyamines separated by high performance cation-exchange liquid chromatography (LC). This effort included optimization of the separation procedure because the background signal was determined to be a sensitive function of the composition of the chromatographic mobile phase. Initial estimates of potential parameters were obtained from an off-line voltammetric study of 1,3-diaminopropane at a gold rotated disk electrode (RDE). Final waveform optimization was based on data obtained during on-line application of the ISWD waveform for 1,3-diaminopropane injected at various times during execution of the mobile phase gradient. The maximum potential in the waveform (EMAX) was chosen to achieve formation of surface oxide (AuO) with concomitant oxidation of the amine without evolution of O2. The minimum potential in the waveform (EMIN) was chosen to achieve reduction of the surface oxide generated at EMAX with minimal reduction of dissolved O2.