Author

Eric Tague

Date of Graduation

Summer 2013

Degree

Master of Science in Chemistry

Department

Chemistry

Committee Chair

Erich Steinle

Keywords

erbium, tetraphenylporphyrin, ion-selective electrodes, benzoate, anion, polymeric membrane, carboxylate, metalloporphyrin

Subject Categories

Chemistry

Abstract

Ion selective electrodes have been used as analytical instruments to accurately measure the concentration of ionic analytes in aqueous solutions since the early 1900's. Over time, the evolution of ion selective electrodes has focused on developing devices that are selective for common anions. To achieve this selectivity, a compound that has specific binding to the anion of choice is utilized, a metalloporphyrin. Metalloporphyrins are ring structured compounds that have a metal bound in the ring's center. Previous work has demonstrated that metalloporphyrin based electrodes have shown to be selective towards a wide variety of anions and is highly dependent on the metal that is used. In attempts to develop a broader range of ion selective electrodes, lanthanide metal-based metalloporphyrins have been investigated as ionophores recently. When an erbium (III) porphyrin is the active ionophore, there is a heightened response to compounds that contained a carboxylate group, such benzoate and salicylate. This project investigates how adding electron withdrawing or donating groups to the aromatic ring of the benzoate anion changes the analytical response (sensitivity and selectivity) of the erbium (III) porphyrin based electrode. Results have shown that adding activating groups enhances response when compared to the reference but response is diminished when compared to the parent compound, benzoate. This provides data for future optimization of ion selective electrodes for carboxylate based analytes.

Copyright

© Eric Tague

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