Galvanostatic control of ion selective electrodes with the solvent polymeric membrane

Graduation date: 2010Detection technique that proposed utilizing electrochemically controlled, reversible ion extraction into polymeric membrane in an alternating galvanostatic/ potentiostatic mode was introduced. This method is studied in detail to comprehend the advantages of the novel sensor (pulstrode) compared to the potentiometric ion selective electrode (ISE), studies included possible applications and limitations. \ud Solvent polymeric membrane of the pulstrode contains a highly lipophilic electrolyte and, therefore does not possess spontaneous ion exchange properties. As a consequence pulstrodes have the ability to determine unbiased selectivity coefficients without the careful counterbalancing of transmembrane ionic fluxes. In contrast to classical ISEs they work under asymmetric conditions. Therefore pulstrodes offer simplicity in the determination of selectivity and the results obtained are prone to less error. Further studies with K⁺, Ag⁺ and Ca²⁺ selective electrodes reveal that pulstrodes yield the same or slightly favorable unbiased selectivity coefficients than the previously reported literature values. Since pulstrodes were demonstrated as reliable sensor to determine unbiased selectivity of neutral carriers, they were used to screen potential anion carriers. Selectivity coefficients for [12]-Mercuracarborand-4 was determined using pulstrodes as well as classical ISEs indicating that it has high selectivity towards I⁻. MC4 may be the most selective I⁻ carrier known to date. \ud Ultimately various aspects of the development of reliable, robust and comparatively maintenance free solid contact sensors using conducting polymer as the transduction layer were considered on a model system. Sodium selective pulstrodes based on poly(3,4-ethylendioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) was identified as the best performing sensor and a protamine selective solid contact pulstrode was fabricated using PEDOT:PSS as the transduction layer. This solid contact pulstrode exhibit a substantial improvement of the low detection limit (0.03 mg/L)