Biomedical subjects

Amanda Sherburn

Publications and source records attributed to Amanda Sherburn.

2 recordsLinked to original sources

PubMed2005

Electrochemically modulated liquid-liquid extraction of ions.

The development of ion extraction methods under electrochemical control via electrochemistry at the interface between two immiscible electrolyte solutions is discussed. A hydrodynamic flow injection system was used for the potentiostatic extraction of non-redox-active species from a flowing aqueous phase into a stationary organogel phase. The ions tetraethylammonium, 4-octylbenzenesulfonate (4-OBSA-), and p-toluenesulfonate (p-TSA-) were studied as model analytes. The extraction study comprised examination of the influence of extraction potentials, aqueous-phase flow rate, and target species concentration. The extraction process can be monitored in situ by means of the ion-transfer current, which has opposing signs for anions and cations. Hydrodynamic voltammograms were obtained from these experiments. The selective extraction of 4-OBSA-, from its mixture with p-TSA-, as well as coextraction of both anions is shown. The results demonstrate the utility of electrochemical modulation for the controlled extraction of ions from an aqueous phase into an organogel electrolyte phase. This offers potential benefits for various analytical processes including sample preparation and cleanup.

Journal Article↗

PubMed2003

Selective silver ion transfer voltammetry at the polarised liquid/liquid interface.

Transfer of silver ions across the water/1,2-dichloroethane interface was studied by cyclic voltammetry (CV). In the absence of added neutral ionophore, Ag+ transferred across the interface when the organic phase contained either tetraphenylborate or tetrakis(4-chloro)phenylborate anions, but this transfer was not possible in the presence of organic phase hexafluorophosphate or perchlorate anions. The ion transfer processes observed were independent of the nature of the organic phase cation. The CV in the presence of tetraphenylborate exhibited a shape consistent with an ion transfer followed by chemical reaction; the rate constant for the following chemical reaction was 0.016 s(-1). In the presence of tetrakis(4-chloro)phenylborate, a return peak equivalent in magnitude to the forward peak was observed, indicative of a simple ion transfer reaction uncomplicated by accompanying chemical reactions. The selectivity of the transfer was assessed with respect to other metal cations: no transfers for copper, cadmium, lead, bismuth, cobalt, nickel, palladium or zinc were observed. The selectivity of the transfer suggests this can form the basis of a selective voltammetric methodology for the determination of silver ions.

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