Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Analytical Chemistry

In this thesis construction and performance characteristics of three types of modified electrodes for the determination of SILC namely screen-printed (SPE), carbon paste (CPE) and the conventional PVC membrane electrodes are demonstrated. All of these electrodes were modified by adding some of SILC ion pairs or their ion pairing agents. All modified electrodes were prepared and optimized by testing the content of each modifier, temperature, pH, response times, life times and applications. SPE incorporated with sodium tetraphenylborate (NaTPB) with dibutylphthalate (DBP) as plasticizer, showed the best electroanalytical performances. SPEs work satisfactorily in the concentration range from 2 x 10⁻⁸ to 1 x 10⁻² mol L-1 with Nernstian compliance of 60.37 ± 1.95 mV decade-1 and detection limit of 2.51 x 10⁻⁸ mol L⁻¹. Fast response time of about 2 s and adequate shelf-life (12 weeks) was achieved. The developed electrodes have been successfully applied for the potentiometric determination of SILC in pharmaceutical formulation under batch and also display good selectivity for SILC drug over large number of inorganic cations, sugars and glycine commonly used in drug formulation

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