Hydrogen ion-selective poly(vinyl chloride) membrane electrode based on a calix[4]arene

Area of Science:

• Electrochemistry
• Analytical Chemistry
• Materials Science

Background:

• Development of ion-selective electrodes is crucial for accurate chemical analysis.
• Poly(vinyl chloride) (PVC) based membranes offer versatile platforms for sensor construction.
• Calixarene derivatives are explored for their ion recognition properties.

Purpose of the Study:

• To construct and characterize a novel hydrogen ion-selective electrode.
• To evaluate the performance of a calixarene derivative as a neutral carrier in a PVC membrane electrode.
• To assess the electrode's applicability in specific chemical environments, such as hydrofluoric acid solutions.

Main Methods:

• Fabrication of a poly(vinyl chloride) (PVC) membrane electrode incorporating 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetracyanomethoxycalix[4]arene as a neutral ion carrier.
• Potentiometric measurements to determine the electrode's response across a defined pH range.
• Selectivity testing against common alkali metal ions (Li+, Na+, K+).
• Evaluation of response time and stability in solution.

Main Results:

• The constructed electrode exhibited an apparent Nernstian response over a pH range of 2-11.5.
• A consistent slope of 54.0 +/- 0.2 mV/pH was observed at 20 degrees C.
• The electrode demonstrated rapid response times and high selectivity for hydrogen ions over lithium, sodium, and potassium ions.
• Performance characteristics were found to be comparable to conventional pH glass membrane electrodes.

Conclusions:

• The calixarene-based PVC membrane electrode is a viable and effective sensor for hydrogen ion detection.
• The electrode's high selectivity and rapid response make it suitable for potentiometric applications, including in hydrofluoric acid solutions.
• Further studies considered the influence of various anions on electrode performance.