Potentiometric Chromate Anion Detection Based on Co(SALEN)₂Ionophore in a PVC-Membrane Sensor

Abstract

Fabrication of a polymeric membrane sensor based on N,N' Bis(salicylidene) ethylenediamino cobalt(II) hydrate (Co(SALEN)2) as an ionophore was focused upon for the purpose of optimizing a PVC matrix. The membrane contained Co(SALEN)2, PVC matrix, 2-Nitrophenyl octyl ether (oNPOE) as a plasticizer, and tetradodecylammonium chloride (TDDACl) as a lipophilic ionic additive with the composition of 5:30:62:3 (w/w), and underwent optimization. The Nernstian slope, detection limit, and response time were −28.33 ± 0.10 mV/decade, 7.9 × 10−7 M, and <10 s respectively. The direct determination of 2 to 48.5 μg/ml of chromate standard solution showed an average recovery of 96.03% and a mean relative standard deviation of 1.6% at 100.0 μg/ml for Co(SALEN)2 sensors. The ionophore functionality in the polymeric membrane and the strengths of anion-carrier interaction were studied by UV–Vis, Fourier transform infrared spectroscopy (FT–IR), and scanning electron microscopy (SEM) analysis.