Scientific article
Open access

Rapid Constant Potential Capacitive Measurements with Solid-Contact Ion-Selective Electrodes Coupled to Electronic Capacitor

Published inAnalytical Chemistry, vol. 92, no. 20, p. 14174-14180
Publication date2020

A constant potential capacitive readout of solid-contact ion-selective electrodes (SC-ISE) allows one to obtain easily identifiable current transients that can be integrated to obtain a charge vs logarithmic activity relationship. The resulting readout can therefore be much more sensitive than traditional open-circuit potentiometry. Unfortunately, however, comparatively long measurement times and significant baseline current drifts make it currently difficult to fully realize the promise of this technique. We show here that this challenge is overcome by placing the SC-ISE in series with an electronic capacitor, with pH probes as examples. Kirchhoff's law is shown to be useful to choose an adequate range of added capacitances so that it dominates the overall cell value. Two different ion-to-electron transducing materials, functionalized single-wall carbon nanotubes (f-SWCNTs) and poly(3-octylthiophene) (POT), were explored as solid-contact transducing layers. The established SC-ISE-based f-SWCNT transducer is found to be compatible with a wide range of external capacitances up to 100 μF, while POT layers require a narrower range of 1–4.7 μF. Importantly, the time for a charging transient to reach equilibrium was found to be less than 10 s, which is dramatically faster than without added electronic component. Owing to the ideal behavior of capacitor, the response current decays rapidly to zero, making the determination of the integrated charge practically applicable.

Research group
  • Swiss National Science Foundation - FN 200021_175622
  • Autre - Developmentand Promotion of Science and Technology Talents Project(DPST) of Thailand
Citation (ISO format)
KRAIKAEW, Pitchnaree, SAILAPU, Sunil Kumar, BAKKER, Eric. Rapid Constant Potential Capacitive Measurements with Solid-Contact Ion-Selective Electrodes Coupled to Electronic Capacitor. In: Analytical Chemistry, 2020, vol. 92, n° 20, p. 14174–14180. doi: 10.1021/acs.analchem.0c03254
Main files (1)
Article (Published version)
ISSN of the journal0003-2700

Technical informations

Creation01/07/2021 3:01:00 PM
First validation01/07/2021 3:01:00 PM
Update time03/15/2023 11:51:29 PM
Status update03/15/2023 11:51:28 PM
Last indexation01/17/2024 12:09:28 PM
All rights reserved by Archive ouverte UNIGE and the University of GenevaunigeBlack