Phd Degree / Doktora
Permanent URI for this collectionhttps://hdl.handle.net/11147/2869
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Doctoral Thesis Minor Components of Olive Oils as Indicators for the Authenticity of Virgin Olive Oils(Izmir Institute of Technology, 2021) Uncu, Oğuz; Özen, Fatma BanuAdulteration of olive oil is a major problem of olive oil industry and may result in health problems as well as unfair earnings. Especially after the update in EU regulations about the labelling of olive oils, a need is arisen to detect the mixtures of old and fresh olive oils. Improvements in detection methods could fall behind of the inventiveness of the fraudsters. Detecting and preventing adulteration could be a challenging task; therefore, new methods and solutions are always in demand to solve this problem. First purpose of this theses is to characterize Aegean region olive oils with respect to their quality parameters such as fatty acid alkyl esters, diacylglycerols, and pigment compositions and to investigate differentiation power of these parameters on harvest year and geographical origin in comparison with spectroscopic methods. It is also aimed to predict these quality parameters by the fast and environmentally friendly ultraviolet-visible (UV-vis) and mid-infrared (mid-IR) spectroscopic techniques in combination with multivariate statistical methods. Finally, the applicability of spectroscopic methods (UV-vis, mid-IR, fluorescent) to detect adulteration of fresh olive oil with old olive oil is investigated. Olive oils were successfully differentiated with respect to geographical location by spectroscopic methods, fatty acid alkyl esters and pigments. In general, prediction of investigated chemical parameters was achieved robustly with mid-IR spectral data except pigments which were estimated better with UV-vis spectral data. Fluorescence and mid-IR + UV-vis spectroscopies were successful in detecting old olive oils in fresh olive oils.Doctoral Thesis Development of Novel Sorbents for the Determination of Mercury in Waters by Cold Vaporatomic Absorption Spectrometry(Izmir Institute of Technology, 2011) Erdem, Arzu; Eroğlu, Ahmet EminMercury is one of the most toxic heavy metal ions to all living organisms. A novel solid support with selective functional groups was developed for mercury sorption from waters prior to its determination by cold vapor atomic absorption spectrometry. The support was prepared by immobilization of several functional groups (amino, mercapto, etc.) on silica. Among the sorbents developed, 3-MPTMS-silica has been shown to be an efficient material for the sorption of mercury species due to its selectivity. Sorption experiments were performed to optimize the necessary parameters and conclusively, sorption pH of 7.0, reaction temperature of 25 oC, sorbent amount of 10.0 mg and shaking time of 30 min were applied throughout the study. Various mineral acids, organic acids, oxidizing agents and sulfur- or nitrogen-containing ligands were tried for the elution of mercury species and 2.0 M TGA was found to offer the maximum desorption. The validity of the method was checked via spike sorption experiments with four different types of water; namely, ultra pure, bottled drinking, tap and sea water. The method worked efficiently (>95%) for all types of water. Permeable reactive barriers, such as zero-valent iron and zero-valent copper were also applied for the removal of mercury species. Similar optimization parameters with 3-MPTMS-silica were also obtained for both sorbents. The method validation was also performed and although sea water is a heavy matrix, high uptake results were achieved for both sorbents.