Chemically modified electrode based on poly[tetra(4-aminophenyl)porphyrin] as a pH sensor

Area of Science:

• Electrochemistry
• Materials Science
• Analytical Chemistry

Background:

• Development of advanced electrochemical sensors is crucial for accurate chemical analysis.
• Platinum electrodes modified with organic polymers offer unique sensing properties.

Purpose of the Study:

• To develop and characterize a novel potentiometric pH sensor using a chemically modified platinum electrode.
• To evaluate the sensor's performance, including its response range, stability, and interference resistance.

Main Methods:

• Chemically modifying a platinum electrode by coating it with poly[tetra(4-aminophenyl)porphyrin].
• Potentiometric measurements to determine the sensor's pH response.
• Assessing resistance to hydrofluoric acid and redox couple interference.
• Studying the a.c. impedance of the polymer membrane.

Main Results:

• The modified electrode exhibited a linear potentiometric response over a broad pH range (1.5-13.7).
• A consistent slope of 55 mV/pH was observed at 20°C.
• The sensor demonstrated fair resistance to hydrofluoric acid erosion and redox interference.
• Effective application in potentiometric titration of hydrofluoric acid.

Conclusions:

• The poly[tetra(4-aminophenyl)porphyrin]-coated platinum electrode is a promising candidate for a robust potentiometric pH sensor.
• Its wide linear range and stability make it suitable for direct pH determination and titration applications.