Preparation and analytical application of new Cr3+-selective membrane electrodes based on acylhydrazone-containing benzimidazole derivatives

New Cr3+-selective poly(vinyl) chloride (PVC) membrane electrodes based on five acylhydrazone-containing benzimidazole derivatives (L1–L5) were developed. Effect of the species and ratios of ionophore, plasticizer, PVC, and lipophilic additive on the potentiometric response of electrodes were investigated in order to determine the electrode specifications. Obtained results showed that the electrodes have the detection limit of 2.0 × 10−7, 3.2 × 10−7, 3.8 × 10−7, 4.6 × 10−7, and 4.0 × 10−7, and have linear response slopes of 19.3, 21.4, 19.6, 22.9, and 21.9 mV/decade in a wide concentration range of Cr3+ ions. According to durability studies, the electrodes can be used for 5 weeks without any considerable divergence in potential values. The proposed sensors revealed acceptable selectivity for Cr3+ over a wide variety of other metal ions. Analytical applications of the electrodes were performed and it was found that developed electrodes can successfully be used as indicator electrodes for the potentiometric titration of Cr3+ ion with EDTA solution and vice versa, as well as in the determination of Cr3+ in alloy, tea leaf, and many water samples. Effect of ligand structure on electrode’s response was also discussed by the data from quantum-chemical calculation.