Date of Graduation

Spring 2014

Degree

Master of Science in Chemistry

Department

Chemistry

Committee Chair

Erich Steinle

Keywords

ion-selective electrode, ionophore, tetraphenylporphyrin, erbium, carboxylate, salicylate, selectivity coefficient, dysprosium, thulium, detection limit

Subject Categories

Chemistry

Abstract

Research has shown that ion selective electrodes (ISEs) with non-Hofmeister selectivity patterns can be created using lanthanide metalloporphyrins as ionophores in polymeric membranes. It was previously determined that erbium(III) tetraphenylporphyrin-based electrodes show enhanced selectivity toward carboxylate-containing anions such as benzoate and salicylate. In this work, the effects of various amounts of cationic additive were examined on polymer membranes made from these ionophores. Potentiometric selectivity coefficients of these ISEs were also determined by comparing the electromotive force (emf) responses of a primary anion versus common interfering anions. Results show that a membrane consisting of approximately 20% cationic additive to ionophore molar ratio provided the greatest selectivity of these sensors towards salicylate. Due to the success found with previous lanthanide metalloporphyrins as ionophores in ISEs, research was extended into the previously unexamined dysprosium(III) and thulium(III) tetraphenylporphyrins. Based on earlier results, the initial calibration studies were completed using polymeric membranes of these ionophores with 20% cationic additive. Preliminary evaluations of these ISEs were conducted using the Hofmeister anions to create several calibration curves. These plots have shown affinity of several anions towards both of these new membranes.

Copyright

© Jennifer Ann Schott

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