Person: KAHRAMAN, MEMET VEZİR
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KAHRAMAN
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MEMET VEZİR
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Publication Metadata only Development of photopolymerized fluorescence sensor for glucose analysis(ELSEVIER SCIENCE SA, 2013) KÖK YETİMOĞLU, ECE; Cubuk, Soner; Yetimoglu, Ece Kok; Kahraman, M. Vezir; Demirbilek, Pinar; Firlak, MelikeThe sensing membrane was prepared by photopolymerization of 4-vinylphenylboronicacid (VPBA), hydroxyethylmethacrylate (HEMA) and poly(ethylene glycol) diacrylate (PEG-DA). The membran is capable of determining glucose between 2.78 x 10(-4) mM and 5.56 x 10(-3) mM with a limit of detection of 0.89 x 10(-5) mM, and limit of quantification 3.17 x 10(-3) mM (n = 7). It can be completely regenerated by using distilled water. The sensor performance characteristics such as response time, dynamic working range and sensitivity were reported. The proposed sensor was then applied successfully for the determination of glucose in blood samples. The optical sensor was stable, cost effective, easy to prepare, rapid and simple for the determination of glucose. (C) 2013 Elsevier B.V. All rights reserved.Publication Metadata only Reusable fluorescent photocrosslinked polymeric sensor for determining lead ions in aqueous media(PERGAMON-ELSEVIER SCIENCE LTD, 2016) KÖK YETİMOĞLU, ECE; Cubuk, Soner; Tasci, Nese; Kahraman, Memet Vezir; Bayramoglu, Allay; Yetimoglu, Ece KokIn this study, l-vinylimidazole units bearing photocured films were prepared as fluorescent sensors towards Pb2+ in aqueous solutions. The influence of experimental parameters such as pH, time and foreign ion concentrations were investigated. Sensor response was linear over a concentration range of 4.83 x 10(-8) to 4.83 x 10(-7) mol L-1. The sensor was highly sensitive with a detection limit as low as 1.87 x 10(-8) mol L-1, and having a selectivity of over four thousand fold. The response time of the sensor was found to be 5 min. When stored in a desiccator at room temperature the sensor showed good stability after a 5 month period. The fluorescence sensors were successful in the determination of Pb2+ in water samples as well as in the determination of the quantitative amount of lead and the results were satisfying. Compared with previously reported literature, the prepared new sensor is highly sensitive and selective. (C) 2016 Elsevier B.V. All rights reserved.Publication Metadata only Recovery of Au(III) ions by Au(III)-imprinted hydrogel(SPRINGER INTERNATIONAL PUBLISHING AG, 2016) KÖK YETİMOĞLU, ECE; Firlak, Melike; Cubuk, Soner; Yetimoglu, Ece Kok; Kahraman, Memet V.A new Au(III)-imprinted hydrogel (Au(III)-Imp) was prepared by the photopolymerisation of 4-acryloylmorpholine (AcM), 2-hydroxyethyl acrylate (HEA), and poly(ethylene glycol) diacrylate (cross-linking monomer, PEG-DA) in the presence of gold ions. In addition, non-imprinted hydrogel (N-Imp) was similarly prepared without Au(III) ions The Au(III)-Imp hydrogel was characterised by several techniques. To achieve the optimal conditions, effect of pH, time, and initial metal ion concentrations were investigated using a batch system. The pre-concentration factor for Au(III) ions was found to be at least 100. The analytical parameters of the method were determined and the method was also successfully applied to computer circuit board scrap samples. The reusability of the Au(III)-Imp hydrogel was also determined. (C) 2016 Institute of Chemistry, Slovak Academy of SciencesPublication Metadata only Phosphonic acid based polymeric fluorescent sensor for Hg(II) analysis(ELSEVIER SCIENCE SA, 2016) KÖK YETİMOĞLU, ECE; Cubuk, Soner; Firlak, Melike; Tasci, Nese; Yetimoglu, Ece Kok; Kahraman, Memet VezirIn this study, vinyl phosphonic acid based highly selective fluorescent sensor was developed for Hg(II) detection in aqueous solution. The sensor showed preferable fluorescence response to mercury ions. Various experimental parameters, such as pH, response time were investigated. The developed sensor showed satisfactory reversibility, reproducibility and response time. The proposed sensor possesses relatively long short term stability of at least 8 h and a life time of 3 months. Working concentration range of the sensor was found to be 2.5 x 10(-8) mol L-1 to 2.5 x 10(-7) mol L-1 and detection limit for mercury ions was 1.3 x 10(-8) Mol L-1. Additionally, the proposed fluorescence sensor was successfully applied to quantitatively determine the amount of mercury in tap water and satisfactory results were obtained. (C) 2015 Elsevier B.V. All rights reserved.Publication Metadata only A novel polymer based fluorimetric sensor for fast and selective determination of chlorpyrifos(ELSEVIER, 2021) KÖK YETİMOĞLU, ECE; Cubuk, Soner; Yetimoglu, Ece Kok; Caliskan, Aynur; Kahraman, Memet VezirIn this study, a spectrofluorometric method has been developed for the determination of chlorpyrifos. For this purpose, firstly, a polymer based membrane has been prepared for chlorpyrifos determination and parameters such as pH, calibration range, sensitivity, selectivity, sensitivity, response time and reproducibility were systematically investigated following the characterization of the membrane. Chlorpyrifos, an organophosphorus pesticide, can be determined by our sensor using the maximum excitation and emission wave lengths at 376 nm and 422 nm, respectively. The measurements can be completed within 20 s and the method also has a very low detection limit of 4.44 ? 10-10 mol L-1. Moreover, the developed polymeric Chlorpyrifos sensor is also suitable for the analysis of chlorpyrifos in tap water and pollen real samples.Publication Metadata only Uptake of Pb2+ Using N-Vinyl Imidazole Based Uniform Porous Hydrogels(TAYLOR & FRANCIS INC, 2011) KÖK YETİMOĞLU, ECE; Firlak, Melike; Cubuk, Soner; Yetimoglu, Ece Kok; Kahraman, Memet VezirThe uniform porous and continuous phase lead (II) adsorbent hydrogel, was prepared by copolymerizing 2-hydroxyethyl methacrylate (HEMA), acrylic acid (AAc), and N,N'-methylenebisacrylamide (MBAAm), with n-vinyl imidazole (VIM). A series of hydrogels, including different ratios of VIM, were prepared by photopolymerization and characterized. The influence of the uptake conditions such as pH, functional monomer percent, contact time, initial feed concentration, and foreign metal ions on the metal ion binding capacity of hydrogel, were also tested. The selective chelation of heavy metal ions from synthetic wastewater was also studied. The affinity order on molar basis was observed as follows: Pb (II) > Zn (II) > Cd (II). Chelation behavior of heavy metal ions could be modelled using both the Langmuir and Freundlich isotherms and it was seen that the Langmuir isotherm model was the best fit for the adsorption of Pb (II) ions in P(VIM/AAc/HEMA) hydrogel. Moreover, the limits of detection and the quantification values were determined. Regeneration of the hydrogels was easily performed with 1M HCl and the same hydrogel can be reused five times almost without any loss of adsorption capacity. All these features make P(VIM/AAc/HEMA) hydrogels potential candidate adsorbent for heavy metal removal.Publication Metadata only UV Cured Polymeric Optical Fluorescence Sensor for the Determination of Au (III)(WILEY-V C H VERLAG GMBH, 2014) KÖK YETİMOĞLU, ECE; Cubuk, Soner; Yetimoglu, Ece Kok; Kahraman, M. Vezir; Kenan, SibelThe recognition and sensing of the biologically and environmentally important metal ions has emerged as a significant goal in the field of chemical sensors in recent years. Among the various analytical methods, fluorescence has been a powerful tool due to its simplicity, high detection limit and application to bio imaging. In this study, UV cured polymeric optical sensor for Au (III) ion based on a fluorescence membrane has been developed. The response characteristics of the sensor including dynamic range, pH effect and response time were systematically investigated. The influences of the conditions such as pH, response time on the metal ion binding capacity of membrane were also tested.Publication Metadata only Photocured thiol-ene based optical fluorescence sensor for determination of gold(III)(ELSEVIER SCIENCE BV, 2014) KÖK YETİMOĞLU, ECE; Cubuk, Soner; Kahraman, Memet Vezir; Yetimoglu, Ece Kok; Kenan, SibelThis study describes the preparation and the characterization of a new thiol-ene based polymeric fluorescence sensor by photo initiated polymerization of trimethylolpropane tris(3-mercaptopropionate), 2-hydroxyethylacrylate, and 2,4,6-triallyloxy-1,3,5-triazine which are used as monomers and also a photo initiator (2,2-dimethoxy-2-phenylacetophenone) for its usage as optical sensor for gold ions. The thiolene based polymeric membrane sensor was characterized by using attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). The response characteristics of the sensors including dynamic range, pH effect, response time, and the effect of foreign ions were investigated. Fluorescence spectra showed that the excitation/emission maxima of the membrane were at 3791425 nm, respectively (C) 2014 Elsevier B.V. All rights reserved.Publication Metadata only UV photocrosslinked polymeric fluorescent sensor for bisphenol A(ELSEVIER SCIENCE BV, 2018) KÖK YETİMOĞLU, ECE; Tasci, Nese; Cubuk, Soner; Firlak, Melike; Yetimoglu, Ece Kok; Kahraman, Memet VezirBisphenol A (BPA) is known as endocrine disrupting compound and it is widely used as an intermediate in manufacturing of polycarbonate and epoxy resins. These resins are used to manufacture inner surface of food cans or directly contact with food and can release BPA into food. It is known that BPA poses health risk, but how risky is a matter of debate. In this study, selective and sensitive fluorescent polymeric membrane sensor for detection of BPA was developed based on fluorescence quenching (lambda ex/lambda em = 272/295 nm). Working concentration range was linear between 4.4 x 10(-9) mol L-1 and 1.1 x 10(-7) mol L-1 with a detection limit of 1.58 x 10(-9) mol L-1. Optimization of sensor was done and the sensor exhibited satisfactory results for being used as a fluorescent sensor for determination of BPA. Additionally, the proposed method was successfully applied to plastic food containers real samples. The developed sensor was shown to be more sensitive than other methods currently in use, and was able to provide results in a matter of seconds, opening up the possibility of a rapid tool for BPA detection.