Mercury(II) ion-selective electrodes based on heterocyclic systems

Area of Science:

• Electroanalytical Chemistry
• Chemical Sensors
• Materials Science

Background:

• Mercury ion detection is crucial due to its toxicity.
• Development of selective and sensitive sensors is an ongoing challenge.
• Polymeric membrane ion-selective electrodes (ISEs) offer a promising approach.

Purpose of the Study:

• To develop novel mercury ion-selective electrodes (ISEs) using specific heterocyclic ionophores.
• To evaluate the potentiometric performance, selectivity, and detection limits of the prepared ISEs for Hg2+.
• To assess the suitability of these ISEs for potentiometric titrations.

Main Methods:

• Preparation of polymeric membrane ISEs incorporating two novel heterocyclic imidazole derivatives as ionophores.
• Conditioning and testing of ISEs for potentiometric response to various common ions.
• Determination of response range, slope, detection limit, and working pH range for Hg2+.
• Evaluation of selectivity against alkali, alkaline-earth, and heavy metal ions.
• Application of ISEs as indicator electrodes in potentiometric titration of Hg2+ with iodide.

Main Results:

• The developed ISEs exhibited a good potentiometric response for Hg2+ over a wide concentration range (5.0 x 10(-5) - 1.0 x 10(-1)M) with near-Nernstian slopes.
• Stable potentiometric signals were achieved rapidly (within 20 s).
• The electrodes demonstrated a low detection limit (1.0 x 10(-5) M) and a working pH range of 1.6-4.4.
• Excellent selectivity for Hg2+ over other tested ions was observed.
• Sharp endpoints were obtained during potentiometric titration of Hg2+ with iodide.

Conclusions:

• The novel heterocyclic imidazole-based ionophores are effective for the development of selective mercury(II) ion-selective electrodes.
• These ISEs offer rapid response, good sensitivity, wide applicability, and excellent selectivity for Hg2+ detection.
• The sensors are suitable for direct potentiometric determination and titration of mercury ions.