New thiocyanate potentiometric sensors based on sulfadimidine metal complexes: experimental and theoretical studies.

Three sulfadimidine metal complexes (M=Fe(III), Cu(II), and Ag(I)) were prepared, characterized, and examined as neutral carriers for the determination of SCN(-) using modified carbon paste electrode. These sensors were successfully applied in the pure samples, and biological fluids. The electrode mechanism was investigated by UV-vis and FT IR. The experimental studies were complemented by quantum chemical calculations at DFT/B3LYP level of theory. The best performance was observed for Cu(II) electrode (C) containing 7.0% complex, 53.0% o-nitrophenyloctyl ether, 37.0% graphite and 3.0% cetylpyridinium chloride, and also for Fe(III)-electrode (A) having 6.0% complex, 52.0% o-nitro phenyloctyl ether, 40.5% graphite and 2.5% cetylpyridinium chloride.