Simplistic approach to formulate an ionophore-based membrane and its study for nitrite ion sensing

Area of Science:

• Electrochemistry
• Materials Science
• Analytical Chemistry

Background:

• Polymeric membranes are crucial for ion-selective electrodes.
• Cobalt complexes show promise as ionophores for sensing applications.
• Accurate nitrite ion detection is vital for environmental and biological monitoring.

Purpose of the Study:

• To develop and optimize a polymeric membrane sensor for nitrite ion detection.
• To investigate the performance characteristics of the fabricated sensor.
• To analyze the structural and chemical properties of the membrane components.

Main Methods:

• Fabrication of a polyvinyl chloride (PVC) based membrane incorporating a cobalt(II) complex as a cobalt ionophore (CI).
• Optimization of membrane composition using 2-nitrophenyl octyl ether (2-NPOE) as a plasticizer and hexadecyl trimethyl ammonium bromide (HTAB) as a cationic additive.
• Characterization of membrane properties using Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), environmental scanning electron microscopy (ESEM), energy-dispersive X-ray spectroscopy (EDS), and optical microscopy.

Main Results:

• The optimized membrane exhibited a Nernstian slope of -0.020 mV per decade.
• A wide detection limit ranging from 1 × 10^-7 M to 3 M was achieved.
• Rapid response (107 ms) and recovery (22 ms) times were recorded for the sensor.

Conclusions:

• The developed polymeric membrane sensor based on a cobalt complex is highly effective for nitrite ion sensing.
• The sensor demonstrates excellent analytical performance, including a broad linear range and fast response.
• Material characterization confirmed the ionophore functionality and interactions within the polymer matrix.