The effect of pH on a multiprotonatable quinidine ion-selective electrode

Area of Science:

• Analytical Chemistry
• Electrochemistry

Background:

• Ion-selective electrodes (ISEs) are crucial for potentiometric measurements.
• Understanding factors influencing ISE performance, such as pH, is vital for accurate analysis.
• Quinidine's electrochemical behavior is relevant in pharmaceutical and clinical settings.

Purpose of the Study:

• To investigate the impact of pH on quinidine ion-selective electrode (ISE) performance.
• To explore how pH variations affect the electroactive material composition within the ISE membrane.
• To propose a model describing the electrode's response to pH changes.

Main Methods:

• Performance evaluation of a quinidine ISE across a range of pH values.
• Analysis of the electroactive material composition in the membrane phase.
• Development and application of a capacitor model for electrode response.

Main Results:

• Solution pH significantly affects the ion-pair composition within the ISE membrane.
• Alterations in ion-pair composition directly influence the electrode's potentiometric behavior.
• The proposed capacitor model effectively describes the observed electrode response.

Conclusions:

• pH is a critical factor influencing quinidine ISE performance.
• The membrane's ion-pair composition is sensitive to bulk solution pH.
• A capacitor model provides a framework for understanding quinidine ISE response mechanisms.