New sensors for determination of tellurite Ion in environmental and biological samples / Nahla Bayoumi Abdelmoniem Mohamed ; Supervised Y. M. Issa , H. M. Abdelfattah , Ola R. Shehab

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

This work has been carried out to present and characterize new selective sensors for determination of tellurite ion. Chemically modified carbon paste sensors sensitive for tellurite were constructed. The performance characteristics of these sensors were studied including slope, linear Nernstain range, detection limit, usable pH, life span, temperature and response time. The tellurit sensors are based on new synthetic complexes (FephenD and FebipyD) that formed from 2 2 the reaction between iron phenanthrolin [Fe(phen)] 2+ and iron bipyridyl 3 [Fe(bipy)] 2+ with diclofenac anion. The prepared sensors were used in the 3 potentiometric determination of tellurite ions in pure solutions, environmental and biological samples. The solubility, solubility products, enthalpy, entropy and free energy change of sparingly soluble tellurite salts were determined successfully using the proposed tellurite sensors. The composition and morphology of the proposed sensors were studied using several microscopic analysis techniques (e.g. scanning electron microscopy (SEM), optical and atomic force microscopy (AFM)). The combination of these techniques provides valuable information on the physical, mechanical and chemical properties of the electrode which proved to be very helpful in understanding its behavior under different chemical conditions

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