Use of self-plasticizing EVA membrane for potentiometric anion detection

Area of Science:

• Electrochemistry
• Materials Science
• Analytical Chemistry

Background:

• Development of selective membranes is crucial for accurate ion determination.
• Anion-selective electrodes offer a pathway for sensitive and specific analyte quantification.
• Previous methods often rely on plasticizers, which can leach and affect sensor performance.

Purpose of the Study:

• To develop and characterize novel anion-selective electrode membranes.
• To evaluate the performance of these membranes for anion determination in steady-state and flow injection analysis (FIA) systems.
• To assess the applicability of the developed sensors for analyzing pharmaceutical samples.

Main Methods:

• Fabrication of five distinct membranes using tri-caprylyl-trimethyl-ammonium chloride (Aliquat-336S) and poly(ethylene-co-vinyl-acetate) (EVA) copolymer.
• Preparation of sensors by solubilizing EVA and Aliquat-336S in chloroform without plasticizers.
• Evaluation of membrane performance in steady-state conditions and in a flow injection analysis (FIA) system with a tubular electrode.
• Determination of salicylate and iodide concentrations in pharmaceutical samples.

Main Results:

• The developed ion-selective electrodes demonstrated utility for anion determination in the concentration range of 10(-5) to 10(-1) mol L(-1).
• In the FIA system, the electrode showed a Nernstian response for salicylate (2.5x10(-3) to 1.0x10(-1) mol L(-1)) and iodide (5.0x10(-4) to 1.0x10(-1) mol L(-1)).
• The sensors achieved a relative deviation of 1.6% when compared to a reference method for salicylate and iodide determination in pharmaceutical samples.

Conclusions:

• Plasticizer-free membranes based on Aliquat-336S and EVA are effective for anion-selective electrodes.
• The developed sensors exhibit good performance in both steady-state and FIA systems.
• The sensors are suitable for the accurate determination of salicylate and iodide in pharmaceutical formulations.