Paper-supported thin-layer ion transfer voltammetry for ion detection

Abstract

We report here on paper-supported thin sample layer voltammetry for the determination of ions. To achieve this goal, a simple setup for the coupling of a commercially available electrode to a silver rod electrode was designed and evaluated for paper-supported thin-layer voltammetry. Linear scan ion transfer voltammetry was explored here for ion-selective membranes doped with an ionophore. The ion-transfer processes and electrochemical behaviors of the system are here evaluated and confirmed by numerical simulation. In the proof-of-concept experiments described, the ions tetrabutylammonium chloride (TBA +) and potassium (K +) were studied as model analytes at membranes without and with ionophore, respectively. A linear relationship from 0.1 mM to 1.0 mM K + was obtained between the charge and ion concentration. The coexistence of background sodium ions did not give appreciable interference, but the background wave was not completely isolated from the analyte wave, as also confirmed by the model. The methodology was successfully demonstrated for determination of K + in mineral water. It is anticipated that this paper-supported thin-layer detection approach may provide an attractive readout protocol for disposable paper-based analytical devices as the methodology does not place strict demands on reference electrode performance.

Potentiometric Sensing

“…Ding et al proposed the interrogation of a paper-supported thin-layer sample by ion-transfer voltammetry. 35 In this setup, a traditional ISE with an inner reference solution was separated from a Ag/AgCl rod with a filter paper strip impregnated with the sample. The Ag/AgCl rod served as a reference/counter electrode.…”

From Molecular and Emulsified Ion Sensors to Membrane Electrodes: Molecular and Mechanistic Sensor Design

“…40 The successful coulometric determination of potassium, 40−43 calcium, 44 and nitrite 45 with ionophore-based ISEs was demonstrated. Different approaches have been proposed to decrease the sample phase dimensions, such as sampling with a paper support 43 or microfluidic devices with a tubular shaped ISE membrane. 42,44,45 Alternatively, membranes thinner than 1 μm have allowed for the establishment of ion transfer voltammetry as an alternative readout of ionophore-based ISEs.…”

Translating potentiometric detection into non-enzymatic amperometric measurement of H2O2

“…In recent years, with the introduction of the new sensing concepts and the instrumental control [2], ISEs have been expanded to be measured under the control of the applied current or potential through a three-electrode system [3], such as thin-layer coulometry [4], chronopotentiometry/galvanostatic polarization [5][6][7][8][9], thin-layer ion transfer voltammetry [10,11], and constant potential coulometry [12]. Meanwhile, the corresponding signal readout strategies, such as coulometric charge [13,14], transition time [15], and voltammetic current [16,17], have been proposed based on the ISEs as the working electrodes.…”