Robust, Bridge‐less Ion‐selective Electrodes with Significantly Reduced Need for Pre‐ and Post‐application Handling

Abstract

We are demonstrating robust, single‐layer ion‐selective electrode (ISE) utilizing simple Ag/AgCl electrode as solid support without the need for intermediate polymer layer. We have created and chemically linked a family of imidazolium ionic liquids (ILs) with poly (vinyl chloride) (PVC) using click chemistry, resulting in hybrid materials with tunable characteristics. The resultant material inherently contains chloride ion thus offering the ability to stabilize interfacial potential. This allowed us to construct very simple, single‐layer membranes with significantly reduced need for conditioning as an added bonus compared to traditional sensors. Chemical immobilization of ISE membrane components also led to extended lifetime as the potential for material loss is reduced and detection limits are lowered. In our characterization we focused on perchlorate as a model ion. It's levels of around 10−7 M could be repeatedly quantified over a 100 day period despite constant exposure of ISEs to aqueous solution over this time. Most importantly, the electrodes exhibited stable and reproducible signal with significantly simplified pre‐ and post‐operation handling protocols. This offers potential for in situ applications as well as to advanced fabrication techniques and miniaturization. Simplicity of construction and operation, and low cost of the solid substrate allows for disposable ISE formats.

Potentiometric Sensing

“…Deviations of the observed selectivity coefficients from the well-known Hofmeister series were found, suggesting binding functionalities of the IL . Schazmann et al reported on a solid-contact anion-SE based on the family of imidazolium salts covalently linked to PVC . Here, the IL, with chloride as a counterion, served as an anion exchanger and a salt bridge, stabilizing the interfacial potential between the Ag/AgCl electrode substrate and the membrane.…”

“…88 Schazmann et al reported on a solid-contact anion-SE based on the family of imidazolium salts covalently linked to PVC. 89 Here, the IL, with chloride as a counterion, served as an anion exchanger and a salt bridge, stabilizing the interfacial potential between the Ag/AgCl electrode substrate and the membrane. The resulting electrodes exhibited close to Nernstian slopes and stable and reproducible signals to different inorganic anions.…”

Simultaneous Detection of Ammonium and Nitrate in Environmental Samples Using on Ion-Selective Electrode and Comparison with Portable Colorimetric Assays

“…Practitioners intending to apply ISEs in the field are typically critical of ISEs’ robustness and precision [ 11 ]. A significant amount of work has been done in recent years to address some of the common criticism [ 12 , 13 , 14 , 15 , 16 ]. Reducing the complexness of operation with ISEs with the view of reducing farmers’ distrust of analytical instrumentation is in a focus of our group.…”