design and construction of cerium selective electrode based on qspr model and experimental evaluation

Abstract: the increased use of ion sensors in different fields leads to many intensive studies to introduce sensing materials in the construction of ion-selective electrodes, particularly lanthanide sensors. since the selectivity of ion-selective sensors, directly depends on the stability constants of ion-ionophore complexes, we predicted the stability constants of cerium ions with different ionophores by the qspr model, previously [1]. although the stability constant of the complex between the ion and the ionophore is required to be high enough to produce a noticeable selectivity, this constant must not be so large that ions are tightly bound, making the complexation process kinetically irreversible, so the sensor exhibits long response time [2]. based on previous studies, the useful range of ionophore complex formation constants in an ise is usually about 104 –107.in this work, we designed and synthesized a new ligand as the selectophore, 3-(2, 3-dihydro-2-methylbenzo[d]thiazol-2-yl)-7-hydroxy-2h-chromen-2-one for cerium ion based on the predictive ga-mlr model and compared the theoretical and practical results. at the first, the stability constant of the cerium-selectophore complex was calculated using the proposed mlr model. then the stability constant of the complex was determined by the conductometric method in acetonitrile solvent and the kinfit program. the obtained results, 3/91 and 4/26 by theoretically and experimentally method, respectively, were satisfactory. potential responses of cerium selective electrode based on the ligand as a selectophore was evaluated by varying the amount of ionophore, plasticizer, and ionic additive. the electrode prepared with 4% ionophore, 61% nitrobenzene, 2% natpb as an additive, and 33% pvc has shown a nernstian slope of 19.18 mv per decade to activities of ce 3+ ions with a short response time of 10 s. the sensor has shown an appreciable selectivity for ce3+ ions in the presence of other lanthanide ions.