A fast response cadmium-selective polymeric membrane electrode based on N,N′-(4-methyl-1,2-phenylene)diquinoline-2-carboxamide as a new neutral carrier

A new polyvinylchloride membrane sensor for Cd2+ ions based on N,N′-(4-methyl-1,2-phenylene)diquinoline-2-carboxamide (Mebqb) as a new and excellent neutral ionophore has been prepared. The sensor shows a Nernestian response for cadmium ions over a wide concentration range (1.0 × 10−6 to 1.0 × 10−1 M) with the determination coefficient of 0.9964 and slope of 29.9 ± 0.5 mV decade−1. The limit of detection is 8 × 10−7 M. It has a fast response time of 3-8 s and can be used for at least 8 weeks without any divergence in potential. The electrode can be used in the pH range from 4.0 to 9.0. The proposed sensor shows a very good discriminating ability towards Cd2+ ion in comparison to some alkali, alkaline earth, transition and heavy metal ions. It was successfully applied for the direct determination of Cd2+in standard and real sample solutions.