A New N-Heterocyclic Carbene Ionophore in Plasticizer-free Polypyrrole Membrane for Determining Ag+ in Tap Water

A bis[1-benzyl-benzimidazoliumethyl]-4-methylbenzenesufonamide bromide ligand (NHCL) as a new type of ionophore was successfully synthesized for the first time and used for the fabrication of Ag+ ion selective electrode as a new type of ionophore, based on the self-plasticizing method. The ionophore was characterized using CHN elemental analysis, FT-IR, 1H NMR, 13C NMR, UV-vis spectroscopic techniques and X-ray single crystal diffraction. The interection between NHCL and Ag+ cation was studied spectrophotometerically and the stoichiometry of the complex (1:2) NHCL:Ag+ in DMSO solvent was determined. The potentiometric response of the electrode toward Ag+ cation was linear from 2.5 × 10−6 to 1.0 × 10−1 M with detection limit of 2.00 × 10−6 M and a Nernstian slope of 58.48 ± 0.75 mV decade−1. The sensor exhibited a response time of about 20 seconds at room temperature and working pH range between 3.5-9.0. The electrode showed a good selectivity towards Ag+ cations in comparison with other soft and hard metals, while most of these metal ions did not show significant interference (KAg+,Mpot). The proposed electrode also applied in the direct determination of Ag+ cations in tap water and standard samples with sensible accuracy and precision.