Highly selective thiocyanate poly(vinyl chloride) membrane electrode based on a cadmium-Schiff's base complex.

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Materials Science

Background:

• The development of selective ion-selective electrodes (ISEs) is crucial for accurate chemical analysis.
• Poly(vinyl chloride) (PVC) membrane electrodes offer versatility in sensor design.
• Cadmium-salen complexes show potential as ionophores for anion recognition.

Purpose of the Study:

• To develop and characterize a novel PVC membrane electrode for thiocyanate (SCN-) anion detection.
• To evaluate the electrode's selectivity, response linearity, and detection limits.
• To assess the practical applicability of the sensor in real-world samples.

Main Methods:

• Fabrication of a PVC membrane electrode incorporating a cadmium-salen complex as the anion carrier.
• Electrochemical measurements to determine the electrode's response characteristics (slope, linear range, detection limit).
• Selectivity studies using the matched potential method to assess interference from other anions.
• Application of the electrode for thiocyanate determination in a milk sample.

Main Results:

• The electrode exhibited an anti-Hofmeister selectivity sequence, preferring thiocyanate over common anions.
• A linear potentiometric response to thiocyanate was observed from 1.0 x 10(-6) to 1.0 x 10(-1) mol L(-1) with a slope of 59.1 mV/decade.
• A low detection limit of 7 x 10(-7) mol L(-1) and a fast response time of approximately 15 seconds were achieved.
• The electrode successfully determined thiocyanate in a milk sample, demonstrating its practical utility.

Conclusions:

• The cadmium-salen complex-based PVC membrane electrode is a highly selective and sensitive sensor for thiocyanate.
• The sensor demonstrates excellent performance over a wide pH range (1.5-11.0).
• The developed electrode provides a reliable method for thiocyanate determination in complex matrices such as milk.