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Potentiometric sensors based on trinuclear chromium(III) pivalates


Author: Dîru Mariana
Degree:doctor of chemistry
Speciality: 02.00.02 - Analytical chemistry
Year:2013
Scientific adviser: Mihail Revenco
doctor habilitat, professor, Moldova State University
Institution: Moldova State University
Scientific council: DH 30-02.00.02-27.03.08
Moldova State University

Status

The thesis was presented on the 7 December, 2012
Approved by NCAA on the 14 June, 2013

Abstract

Adobe PDF document0.28 Mb / in romanian

Keywords

trinuclear chromium(III) pivalates, ion-selective electrodes, potentiometric sensors, ionophores, potentiometric titration, direct potentiometric method

Summary

Potentiometric sensors based on trinuclear chromium(III) pivalatesˮ. Doctor’s thesis in Chemistry. Chisinau, 2012. Introduction, three chapters, conclusions, bibliography of 153 references, 116 pages of main text, 28 figures and 35 tables. The results are published in 17 scientific papers. Keywords: trinuclear chromium(III) pivalates, ion-selective electrodes, potentiometric sensors, ionophores, potentiometric titration, direct potentiometric method. Area of Research and Objectives. The thesis belongs to the analytical chemistry domain and was aimed at investigating the possibility of using trinuclear chromium(III) carboxylates as new effective and efficient electroactive materials for potentiometric sensor membranes, sensitive to the presence of anionic species (perchlorate, nitrate, thiocyanate, salicylate, dodecylsulfate, tetraphenylborate, perrhenate), and with chemometric parameters good enough for the analysis of these species in real objects. For solving these problems the mains objectives were: the synthesis and study of trinuclear chromium(III) pivalates, which contain as anions the above mentioned species; preparation, optimization of the composition of poly(vinylchloride) membranes and of the operation regime of the sensors; elaboration of potentiometric methods for determination of anionic species in real objects using these sensors. Scientific Novelty and Originality. New original methods for the synthesis of the compounds with above mentioned anions have been developed. These complex systems have been used for preparation of the membranes and anionic potentiometric sensors have been elaborated. The analytical and functional parameters (concentration range where the potential changes with pA linearly, the slope of the calibration curve, selectivity, response time and life time) have been determined. The interference of other species on these parameters and behavior of the electrodes in policomponent systems were studied. The tetraphenylborate-selective electrode was developed for the determination of the end point in titration of sodium tetraphenylborate solution with solutions containing potassium ions. The scientific problemsolved in the thesis is the improvement of functional parameters of sensors, based on trinuclear chromium(III) pivalates and 4,4΄-bipyridyl, by assembling in situ the electroactive materials during the formation of membranes. Theoretical and Application Value. It was demonstrated that the use of the synthesis of the electroactive material in situ during the formation of the membrane increasios the life time of the anionic potentiometric sensors, wich ones can be used for determination of the perchlorates, nitrates, thiocyanates, salicylates, dodecylsulfates and perrhenate. The application value has been supplemented by developping a new potentiometric titration method for the determination of the potassium contents. There have also been proposed potentiometric methods have been applied for analysis of the ions in real systems.