Potentiometric flow injection system for determination of reductants using a polymeric membrane permanganate ion-selective electrode based on current-controlled reagent delivery

Abstract

a b s t r a c tA polymeric membrane permanganate-selective electrode has been developed as a current-controlled reagent release system for potentiometric detection of reductants in flow injection analysis. By applying an external current, diffusion of permanganate ions across the polymeric membrane can be controlled precisely. The permanganate ions released at the sample-membrane interface from the inner filling solution of the electrode are consumed by reaction with a reductant in the sample solution thus changing the measured membrane potential, by which the reductant can be sensed potentiometrically. Ascorbate, dopamine and norepinephrine have been employed as the model reductants. Under the optimized conditions, the potential peak heights are proportional to the reductant concentrations in the ranges of 1.0 × 10 −5 to 2.5 × 10 −7 M for ascorbate, of 1.0 × 10 −5 to 5.0 × 10 −7 M for dopamine, and of 1.0 × 10 −5 to 5.0 × 10 −7 M for norepinephrine, respectively with the corresponding detection limits of 7.8 × 10 −8 , 1.0 × 10 −7 and 1.0 × 10 −7 M. The proposed system has been successfully applied to the determination of reductants in pharmaceutical preparations and vegetables, and the results agree well with those of iodimetric analysis.

Potentiometric flow injection sensing system for determination of heparin based on current-controlled release of protamine

“…This effect may be due to the fact that the protamine molecules with high molecular weights need a rather long time to cross the membrane [13]. Recently, it has been found that the ion fluxes across the membrane can be modulated and controlled precisely by applying an external current [23,[30][31][32]. Previous reports have shown that ions across the polymeric membrane ion-selective electrode can be selectively and precisely delivered to the sample solution for calibration-free titrations [33].…”

Determination of the Total Phenolic Content in Wine Samples Using Potentiometric Method Based on Permanganate Ion as an Indicator

“…Currently, the potential change of the electrode is related to the concentration of the measured substance. Potentiometric analytical methods based on a permanganate release system, for example, have been developed for potentiometric detection of reductants such as dopamine and ascorbate [21,22]. Nevertheless, intense research efforts still focus on their new applications and, herein, ions for the evaluation of the total phenolic content in wine is the emphasis.…”

Modeling the response of a control-released ion-selective electrode and employing it for the study of permanganate oxidation kinetics

“…Particularly, our group has developed an ionophorefree permanganate ISE that utilizes outward ion uxes through the membrane to provide control-released substrates for monitoring the analytes of interest. 16,19 Previous studies have shown that the design based on permanganate release allows a sensitive and reproducible detection of reductants including ascorbate and dopamine. However, the application of this technique is still limited since all reductants that can efficiently react with permanganate ions may produce measured potential interference.…”