Solid-state ion-selective electrodes for the potentiometric determination of phosphate

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Materials Science

Background:

• Potentiometric determination of phosphate is crucial in various fields.
• Existing ion-selective electrodes for phosphate often face limitations in sensitivity or interference.
• Development of robust and reliable solid-state sensors is an ongoing challenge.

Purpose of the Study:

• To develop and investigate novel solid-state ion-selective electrodes for the potentiometric determination of phosphate.
• To evaluate the performance characteristics of the developed electrodes, including response, sensitivity, and interference.

Main Methods:

• Fabrication of solid-state ion-selective electrodes with membranes composed of silver sulfide, lead sulfide, and lead hydrogen phosphate.
• Investigation of electrode properties using potentiometric measurements.
• Testing response to orthophosphate ions at varying concentrations and pH.
• Assessment of interference from common anions like sulfate, bicarbonate, nitrate, and chloride.
• Application of the electrode in potentiometric precipitation titration of phosphate with lanthanum.

Main Results:

• The most successful electrode exhibited a theoretical Nernstian response to orthophosphate ions down to 5 µg/ml total phosphate at pH 8.3.
• The electrode demonstrated a slow response time and a changing standard potential over time.
• Sulfate, bicarbonate, and nitrate ions showed no significant interference.
• Chloride interference was transient and less severe compared to other phosphate electrodes.
• The electrode performed effectively as an indicator in potentiometric precipitation titrations.

Conclusions:

• A novel solid-state ion-selective electrode based on silver sulfide, lead sulfide, and lead hydrogen phosphate shows potential for phosphate determination.
• The electrode offers good selectivity against common anions, with manageable transient chloride interference.
• Further optimization may be needed to address response time and standard potential stability for broader applications.