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

A polymeric membrane based on a N,N'-bis(salicylidene)ethylenediaminocobalt(ii) complex as a cobalt ionophore (CI) was fabricated and optimized for nitrite ion sensing application. The membrane contained CI, 2-nitrophenyl octyl ether (2-NPOE) as a plasticizer and hexadecyl trimethyl ammonium bromide (HTAB) as a cationic additive in a polyvinyl chloride (PVC) matrix. The Nernstian slope (-0.020 mV per decade), detection limit (1 × 10^-7 M to 3 M), and response (107 milliseconds) and recovery (22 milliseconds) times were recorded for optimum membrane composition. The ionophore functionality in the polymer matrix and their interaction were studied 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 analyses.