Development of nano material based sensors for determination of some-cation/anion in groundwater and complementary usage of ion chromatography

In this thesis, novel materials using electrospun nano-scale polymeric fibers has been proposed as a promising material for sensing trace amounts of cations in water and groundwater systems. The offered sensors operate by detecting fluorescence intensity changes of fluoroionophore embedded in polymer matrices. The spectral characterization and sensor properties of seven different ionophores were described. Some of the exploited dyes were newly synthesized and used for the first time for sensing purposes. Highly sensitive emission based nano-scale sensors for Copper (II), Mercury (II), Iron (III) and Tin (II) were fabricated. We performed spectral characterizations of the ionophores in conventional solvents and in solid matrices. Then, we investigated the selectivity and following the sensor performances of the ionophores into detail in terms of sensitivity, selectivity, working range, short-term stability and response time. We checked accuracies of the offered sensors exploiting recovery tests and used them in real groundwater samples. A great effort has also been made for development of a sensor to detect the conventional anions throughout the studies. We observed a significant response only for bicarbonate and hydroxyl ions with ODC-3 and ODC-5 dyes. The observed response was not a selective response for bicarbonate but rather, a response to pH in the alkaline range of the pH scale. Throughout the thesis, for each fluoroionophore, we compared results of thin films and electrospun nanofibers and revealed the advantages of the nano-scale materials over existing thin films. Here, we performed coupling of electrospun nanomaterials with fluorescence based measurement techniques without scattering and other side effects. By this way, we attained detection limits extending to sub-picomolar levels. Further efforts will focus on exploring new sensing materials and polymer compositions, controlling the nanoscale size of the electrospun membranes, and optimizing the sensitivities for the detection of a variety of analyses. Keywords: Sensor, nanosensor, optical chemical sensor, fluorescence, Hg (II),