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 x 10(-7) M, and <10 s respectively. The direct determination of 2 to 48.5 mu g/ml of chromate standard solution showed an average recovery of 96.03% and a mean relative standard deviation of 1.6% at 100.0 mu g/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. (C) 2014 The Electrochemical Society. All rights reserved.