Optimizing Salt Lipophilicity for Reference Electrodes Based on Organic Electrolytes.
- 1Department of Inorganic and Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland.
- 2Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand.
Abstract
Reference electrodes (REs) based on membranes doped with organic electrolytes offer an attractive route toward versatile, miniaturized, and maintenance-free sensing platforms. Nevertheless, the choice of the reference electrolyte remains a critical design parameter that determines the performance of the corresponding REs. Different ranges of ionic liquid and solid organic salt lipophilicity have previously been explored for RE design, each characterized by different intrinsic limitations. Although the increased partitioning of less lipophilic electrolytes from the reference membrane to the sample establishes stable RE potentials, it also results in rapid electrolyte loss and sample contamination. This might in principle be mitigated with highly lipophilic organic electrolytes, but even minor deviations from the ideal stoichiometric composition of such salts induce parasitic responses of the RE to sample species. To combine the advantages of both characteristics, we investigate here the intermediate electrolyte lipophilicity range that has largely remained underexplored for RE design. Ionic liquids with lipophilicities exceeding that of commercial analogues based on the bis-(trifluoromethanesulfonyl)-imide ([C₁C₁N⁻]) anion were prepared via potentiometric titrations by systematically varying the lipophilicity of the tetraalkylammonium used as countercation. The best-performing composition, based on tetrahexylammonium ([THA⁺]-[C₁C₁N⁻]), provided reproducible and stable reference electrode potentials in both bulk solutions and under flow conditions, giving a potential variation of only 0.16 mV for solutions bracketing the physiological electrolyte range. This stability was accompanied by dramatically reduced leaching of the salt from the membrane, which was confirmed via quartz crystal microbalance measurements and the absence of chemical poisoning of ion-selective membranes placed in the same solution.
Related
- Real-Time Neurotransmitter Sensing in Midbrain Organoids Using 3D Carbon Cup Electrodes
- A novel method for obtaining epileptic brain tissue for omic analyses using electrodes from a clinical stereoelectroencephalography study
- Progress in flame-retardant solid-state electrolytes for battery safety and sustainability
- Injectable Nanoparticles Assemble In Situ into Modular, Functionally Segmented Brain Electrodes
- Multi-day recalibration-free electrophysiology interface based on carbon nanotube thin film dry electrodes
BibTeX
@article{tiuftiakov2026optimizing,
title = {{Optimizing Salt Lipophilicity for Reference Electrodes Based on Organic Electrolytes.}},
author = {Nikolai Yu Tiuftiakov and Supakron Kittikomoldej and Eric Bakker},
journal = {ACS measurement science au},
year = {2026},
month = aug,
doi = {10.1021/acsmeasuresciau.6c00145},
url = {https://europepmc.org/article/MED/42921444},
note = {CC BY},
}
RIS
TY - JOUR
TI - Optimizing Salt Lipophilicity for Reference Electrodes Based on Organic Electrolytes.
AU - Nikolai Yu Tiuftiakov
AU - Supakron Kittikomoldej
AU - Eric Bakker
PY - 2026
DA - 2026/08/03
JO - ACS measurement science au
DO - 10.1021/acsmeasuresciau.6c00145
UR - https://europepmc.org/article/MED/42921444
AB - Reference electrodes (REs) based on membranes doped with organic electrolytes offer an attractive route toward versatile, miniaturized, and maintenance-free sensing platforms. Nevertheless, the choice of the reference electrolyte remains a critical design parameter that determines the performance of the corresponding REs. Different ranges of ionic liquid and solid organic salt lipophilicity have previously been explored for RE design, each characterized by different intrinsic limitations. Although the increased partitioning of less lipophilic electrolytes from the reference membrane to the sample establishes stable RE potentials, it also results in rapid electrolyte loss and sample contamination. This might in principle be mitigated with highly lipophilic organic electrolytes, but even minor deviations from the ideal stoichiometric composition of such salts induce parasitic responses of the RE to sample species. To combine the advantages of both characteristics, we investigate here the intermediate electrolyte lipophilicity range that has largely remained underexplored for RE design. Ionic liquids with lipophilicities exceeding that of commercial analogues based on the bis-(trifluoromethanesulfonyl)-imide ([C₁C₁N⁻]) anion were prepared via potentiometric titrations by systematically varying the lipophilicity of the tetraalkylammonium used as countercation. The best-performing composition, based on tetrahexylammonium ([THA⁺]-[C₁C₁N⁻]), provided reproducible and stable reference electrode potentials in both bulk solutions and under flow conditions, giving a potential variation of only 0.16 mV for solutions bracketing the physiological electrolyte range. This stability was accompanied by dramatically reduced leaching of the salt from the membrane, which was confirmed via quartz crystal microbalance measurements and the absence of chemical poisoning of ion-selective membranes placed in the same solution.
SN - 2694-250X
ER -