Development of optical sensors for toxic metals

The first chapter of the thesis gives general information about molecular luminescence spectrometry. This begins with information about the definition of sensors and their application areas, then the classification of the sensors were made and their advantages and disadvantages were compared. Furthermore, the plasticizers, indicators and polymeric supports used in the preparation of optodes were explained in detail. Also, the immobilization techniques used in the development of optical sensors and the recent developments of optical sensors research were provided. Finally, the general knowledge of the toxic metals used in this thesis was given. The second part of the thesis explains the experimental process. Reagents and devices used in this thesis have been written. Cocktail preparation protocols have been explained. In the third chapter of this study, a highly sensitive determination of Cd2+ was accomplished by using new sensors prepared by newly synthesized Chloro-acetic acid N-[4-3-methyl-3-phenyl-cyclobutyl)-thiazol-2-yl]-N'-pyridin-2-ylmethylene-hydrazide (CTH) ligand into PVC films. The photophysical and photochemical characteristics of this ligand in different solvents and in a plasticized PVC matrix were determined. The sensor performance characteristics such as pH effects, ion sensitivity, selectivity over a number of anions and cations, photostability and regeneration studies were reported. The membrane was sensitive to Cd2+ in the 1.0 x 10-10 – 1.0 x 10-5 M range and the response has become stable after 25 minutes. No significant effect of interferents studied was observed at the working wavelength. The sensor can be regenerated by treatment with 0.1 M EDTA. The sensor was applied to the determination of cadmium in real samples. In the fourth chapter of this study, a highly sensitive determination of Pb2+ was accomplished by using new sensors prepared by newly synthesized 3,5-dimethoxy-2-((2-(4-(3-methyl-3-phenylcyclobutyl)thiazol-2-yl)hydrazono)methyl)phenol (DHM) ligand into PVC films. The membrane response was sensitive to Pb2+ in the 4.82 x 10-10 – 4.82 x 10-4 M range and the response has become stable after 50 minutes. No significant effect of interferents was observed at the working wavelength. The sensor can be regenerated by treatment with 0.2 M EDTA. The sensor was applied to the determination of lead in real samples. In the last chapter of this study, a highly sensitive determination of Hg2+ was accomplished by using newly prepared sensor based on newly synthesized 2-(2-(hydroxyimino)-2-(3-methyl-3-phenylcyclobutyl)ethyl) isoindoline-1,3-dione (HID) ligand in PVC films. The membrane response was sensitive to Hg2+ in the 5.0 x 10-10 – 5.0 x 10-5 M range and the respond has become stable after 16 minutes. No significant effect of interferents was observed at the working wavelength. The sensor can be regenerated by treatment with 0.2 M EDTA. The sensor was applied to the determination of mercury in real samples.