A novel potentiometric self-plasticizing polypyrrole sensor based on a bidentate bis-NHC ligand for determination of Hg(ii) cation

Abstract

In this approach, a new potentiometric self-plasticizing polypyrrole sensor was constructed based on a bidentate bis-NHC ligand for the purpose of Hg²⁺ cation determination. An ionophore, namely bis[1-benzyl-benzimidazoliumethyl]-4-methylbenzenesulfonamide bromide (NHCL) was successfully synthesized and characterized using FT-IR, ¹H NMR, ¹³C NMR spectroscopy, CHN elemental analysis, X-ray single crystal diffraction and UV-Vis spectroscopy. The electrode with a membrane optimum composition demonstrated a good Nernstian response to Hg²⁺ cations ranging from 1.0 × 10⁻⁶ to 1.0 × 10⁻² M with a detection limit of 2.5 × 10⁻⁷ M and a Nernstian slope of 28.10 ± 0.29 mV per decade over a pH range between 4.5–7.0 with a response time of about 20 seconds at room temperature. The electrode exhibited better selectivity towards Hg²⁺ ions in comparison with some soft and hard metals; most of these metal ions do not show significant interference . The proposed electrode also has applications in the direct determination of Hg²⁺ cations in aqueous solutions with sensible accuracy and precision.