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In this study, a highly sensitive PVC-membrane sensor based on 4-methoxyphenylcyanamide (4-MeOpcyd) as a neutral carrier was prepared and the specific interaction between Gd 3 + ions and ionophore at the surface of selective polymeric membrane was calculated using the PM6/SPARKLE semiempirical method. The results of the Mopac2009 calculations show selective complexation of Gd 3 + by 4-MeOpcyd ligand that correlate quite well with experimental data. This membrane sensor has a linear response in the range of 1.0 10 À6 -1.0 10 À2 M Gd 3 + with detection limit of 6.2 10 À7 M. This electrode was applied in potentiometric titration for determination of gadolinium and also for fluoride ions in the mouthwash samples with satisfactory results.

Functionalized‐multiwall carbon nanotubes decorated with redox active copper nanoparticles have been fabricated for sensitive enzyme‐less H2O2 detection. The new nanocomposite was characterized by Transmission electron microscopy, energy dispersive X‐ray analysis and cyclic voltammetry. The response of the modified electrode to H2O2 was examined using amperometry at −0.45 V vs. Ag/AgCl in a buffer solution at pH 10.0. The developed sensor displayed linear concentration ranges of 0.5–10.0 and 10.0–10000.0 µmol L−1 with a detection limit of 0.3 µmol L−1. The proposed sensor displayed good selectivity for H2O2 detection in the presence of common interferences such as ascorbic acid.