A new polarography was studied with dropping carbon fluid electrode (DCFE), composed of graphite powder and low-viscosity liquid paraffin. By using a stainless steel capillary with 0.37 mm inner diameter and a very dense electrolyte solution of saturated CsCl (~ 10 M), nearly spherical carbon drops of about 2 mm at the maximum size were obtained reproducibly. Well-defined polarograms of ferrocenecarboxylate (FcCOO−) with clear limiting currents were observed at this dropping electrode. The slope of the log plot of the polarogram was 66.6 mV, which was close to the theoretical value of reversible wave (59.2 mV at 25 °C). By achieving the nearly reversible polarographic wave, limiting currents could be observed more clearly than our previous study, in which broadened polarograms had been obtained due to a considerable IR drop at high concentrations. Potential of zero charge of DCFE was also measured and discussed.Download high-res image (172KB)Download full-size image

The transfer of the cationic forms of tryptamine and serotonin across the nitrobenzene (NB)/water (W) interface was studied by cyclic voltammetry. Well-defined voltammetric waves were observed within the potential window. The standard potentials of the transfer were determined from the midpoint potentials of the voltammograms. The transfer of the cationic form of tryptophan across the NB/W interface was also observed using an acidic aqueous solution.Highlights► The transfer of cationic forms of tryptamine, serotonin, and tryptophan. ► That happened at a liquid–liquid interface by cyclic voltammetry. ► It is successfully determined the hydrophobicity parameters of these ions. ► This is the first report of the ion transfer voltammetry of them.