Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 169Citation - Scopus: 177Thin Film Microextraction: Towards Faster and More Sensitive Microextraction(Elsevier Ltd., 2019) Ölçer, Yekta Arya; Tascon, Marcos; Eroğlu, Ahmet Emin; Boyacı, EzelThin film microextraction (TFME) is an analytical tool that has been proven to be suitable for integrated sampling and sample preparation of a wide variety of routine and on-site applications. Compared to the traditional microextraction techniques, the most important advantage of TFME is its enhanced sensitivity due to the relatively larger extractive phase spread over a larger surface area. The technique, in this way, facilitates fast extraction kinetics and high extractive capacity. Moreover, TFME offers high versatility for device development over classical SPME technologies due to the plethora of available extractive phases, coating methods and geometry options. The goal of this review is to provide a comprehensive summary of the contemporary advances in this exciting field covering novel extractive phases, technological and methodological developments, and relevant cutting-edge applications. Finally, a critical discussion of the future trends on TFME is also presented. (C) 2019 Elsevier B.V. All rights reserved.Article Citation - WoS: 41Citation - Scopus: 40Biosorption of Cu(ii) and Pb(ii) Ions From Aqueous Solution by Natural Spider Silk(Elsevier Ltd., 2011) Pelit, Levent; Ertaş, Fatma Nil; Eroğlu, Ahmet Emin; Shahwan, Talal; Tural, H.Aside from its excellent mechanical properties, spider silk (SS) would offer an active surface for heavy metal interaction due to its rich protein structure. The present study describes the potential use of natural (SS) as a sorbent of heavy metals from aqueous solutions. Single and multi-species biosorption experiments of heavy metals by natural SS were conducted using batch and column experiments. The biosorption kinetics, in general, was found to follow the second-order rate expression, and the experimental equilibrium biosorption data fitted reasonably well to Freundlich isotherm. From the Freundlich isotherm, the biosorption capacities of Cu(II) and Pb(II) ions onto SS were found as 0.20 and 0.007mmolg -1, respectively. The results showed a decrease in the extent of metal ion uptake with lowering the pH.Article Citation - WoS: 20Citation - Scopus: 24Preparation and Characterization of Sodium Dodecyl Sulfate Doped Polypyrrole Solid Phase Micro Extraction Fiber and Its Application To Endocrine Disruptor Pesticide Analysis(Elsevier Ltd., 2013) Korba, Korcan; Pelit, Levent; Okçu Pelit, Füsun; Özdokur, K. Volkan; Ertaş, Hasan; Eroğlu, Ahmet Emin; Ertaş, Fatma NilA robust in house solid-phase micro extraction (SPME) surface has been developed for the headspace (HS)-SPME determination of endocrine disruptor pesticides, namely, Chlorpyrifos, Penconazole, Procymidone, Bromopropylate and Lambda-Cyhalothrin in wine sample by using sodium dodecylsulfate doped polypyrrole SPME fiber. Pyrrole monomer was electrochemically polymerized on a stainless steel wire in laboratory conditions in virtue of diminishing the cost and enhancing the analyte retention on its surface to exert better selectivity and hence the developed polymerized surface could offer to analyst to exploit it as a fiber in headspace SPME analysis. The parameters, mainly, adsorption temperature and time, desorption temperature, stirring rate and salt amount were optimized to be as 70°C and 45min, 200°C, 600rpm and 10gL-1, respectively. Limit of detection was estimated in the range of 0.073-1.659ngmL-1 for the pesticides studied. The developed method was applied in to red wine sample with acceptable recovery values (92-107%) which were obtained for these selected pesticides.Article Citation - WoS: 67Citation - Scopus: 80Metal Ion Release From Tin Coated Cocrmo Orthopedic Implant Material(Elsevier Ltd., 2006) Türkan, Uğur; Öztürk, Orhan; Eroğlu, Ahmet EminIn this study, a medical grade CoCrMo alloy was coated with TiN by means of physical vapor deposition (PVD) technique at 550 °C for 6 h. The TiN layer microstructure and thickness were studied by X-ray diffraction (XRD) and cross-sectional scanning electron microscopy (SEM). The adhesive strength of the TiN coatings on the CoCrMo substrate was studied by a commercially available Scanning Scratch Tester. Static immersion test was conducted to investigate the effectiveness of TiN coating in preventing the dissolution of metal ions into the simulated body fluid (SBF) from the substrate by atomic absorption spectrometry (AAS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The XRD results showed that the PVD coated TiN films exhibited (111) preferred orientation, while the SEM analysis indicated quite uniform and highly dense TiN coated layer (about 3 μm thick) with a columnar growth mode reaching from substrate to coating surface. The scratch test results showed that the adhesive strength between the TiN film and the CoCrMo substrate was adequate. The AAS and ICP-OES results showed that the presence of the TiN coating prevented the release of cobalt and chromium metal ions from the substrate CoCrMo alloy whereas cobalt was preferentially dissolved from the as-polished material. Calcium phosphate precipitation was observed on the surface of the as-polished material, indicating a degree of bioactivity of the as-polished surface which is absent in the TiN coated substrate alloy.Article Citation - WoS: 82Citation - Scopus: 92Metal Ion Release From Nitrogen Ion Implanted Cocrmo Orthopedic Implant Material(Elsevier Ltd., 2006) Öztürk, Orhan; Türkan, Uğur; Eroğlu, Ahmet EminCoCrMo alloys are used as orthopedic implant materials because of their excellent mechanical and corrosion properties. However, when placed in vivo, these alloys release Co, Cr, Mo ions to host tissues, which may give rise to significant health concerns over time. Nitrogen ion implantation can be used to form protective layers on the surface of CoCrMo orthopedic alloys by modifying the near surface layers of these materials. In this study, medical grade CoCrMo alloy (IS0 5832-12) was ion implanted with 60 keV nitrogen ions to a high dose of 1.9 × 10 18 ions/cm 2 at substrate temperatures of 100, 200 and 400 °C. The N implanted layer microstructures, implanted layer phases, and thicknesses were studied by a combination of Bragg-Brentano (θ/2θ) and grazing incidence (Seeman-Bohlin) X-ray diffraction (XRD and GIXRD) and cross-sectional scanning electron microscopy (SEM). Atomic force microscopy (AFM) was used for roughness analysis of N implanted as well as as-polished surfaces. Static immersion tests were performed to investigate metal ion release into simulated body fluid (SBF) by electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma optical emission spectrometry (ICP-OES). XRD and SEM analyses indicated that the N implanted layers were ∼ 150-450 nm thick and composed of the (Co,Cr,Mo) 2+xN nitride phase and a high N concentration Co-based FCC phase, γ N depending on the substrate temperature. ETAAS analysis results showed that in vitro exposure of the N implanted surfaces resulted in higher levels of cobalt ion release into the simulated body fluid compared to the untreated, polished alloy. The higher Co release from the N implanted specimens is attributed to the nature of the implanted layer phases as well as to the rougher surfaces associated with the N implanted specimens compared to the relatively smooth surface of the untreated material. SEM analysis of N implanted and untreated specimens after immersion tests clearly indicated calcium phosphate formation on the as-polished CoCrMo alloy, indicating a degree of bioactivity of the untreated metal surface which is absent in the N implanted specimens.Article Citation - WoS: 28Citation - Scopus: 28Speciation and Preconcentration of Inorganic Antimony in Waters by Duolite Gt-73 Microcolumn and Determination by Segmented Flow Injection-Hydride Generation Atomic Absorption Spectrometry (sfi-Hgaas)(Elsevier Ltd., 2005) Erdem, Aslı; Eroğlu, Ahmet EminA selective matrix removal/separation/enrichment method, utilizing a microcolumn of a chelating resin with SH functional groups (Duolite GT-73), was proposed for the determination of Sb(III) in waters by segmented flow injection-hydride generation atomic absorption spectrometry (SFI-HGAAS). The resin was selective to Sb(III) at almost all pH and acidity values employed, whereas Sb(V) was not retained at all and could be determined after a pre-reduction step with l-cysteine. Spike recoveries were tested at various concentration levels in different water types and were found to vary between 85 and 118%. Accuracy of the proposed methodology was checked by analyzing a standard reference material and a good correlation was found between the determined (13.3 ± 1.1 μg l-1) and the certified value (13.79 ± 0.42 μg l-1). The method was applied to several bottled drinking water samples for antimony determination with and without preconcentration and none of the samples were found to contain antimony above the permissible level (5 μg l-1). The characteristic concentration (the concentration of the analyte corresponding to an absorbance of 0.0044) was 0.55 μg l-1 and the 3 s limit of detection (LOD) based on five times preconcentration was 0.06 μg l-1. The applicability of the microcolumn separation/preconcentration/matrix removal method for flow injection systems was also demonstrated.Article Citation - WoS: 87Citation - Scopus: 108Synthesis and Characterization of Bentonite/Iron Nanoparticles and Their Application as Adsorbent of Cobalt Ions(Elsevier Ltd., 2010) Shahwan, Talal; Üzüm, Çağrı; Eroğlu, Ahmet Emin; Lieberwirth, IngoThis study reports the synthesis and characterization of iron nanoparticles in the presence of K10 bentonite. Introducing K10 during synthesis of iron nanoparticles resulted in a partial decrease in the aggregation of the nanoparticles. The dispersed nanoparticles showed a typical core–shell structure and were predominantly within the 10–60 nm size range. The composite adsorbent was tested for the removal of Co2+ ions in aqueous solution at various contact times, concentrations, pH, and repetitive loadings. The rate of adsorption was evaluated using first and second order rate equations. The adsorption was described by the Freundlich model. The adsorbent showed effective removal after re-use and the adsorption increased with increasing initial pH.Article Citation - WoS: 17Citation - Scopus: 17Separation of Trace Antimony and Arsenic Prior To Hydride Generation Atomic Absorption Spectrometric Determination(Elsevier Ltd., 2005) Ural, Müşerref Yersel; Erdem, Aslı; Eroğlu, Ahmet Emin; Shahwan, TalalA separation method utilizing a synthetic zeolite (mordenite) was developed in order to eliminate the gas phase interference of Sb(III) on As(III) during quartz furnace hydride generation atomic absorption spectrometric (HGAAS) determination. The efficiency of the proposed separation method in the reduction of suppression effects of transition metal ions on As(III) signal was also investigated. Among the volatile hydride-forming elements and their different oxidation states tested (Sb(III), Sb(V), Se(IV), Se(VI), Te(IV), and Te(VI)), only Sb(III) was found to have a signal depression effect even at low (μg l−1) concentrations under the experimental conditions employed. It has been shown that mordenite adsorbs Sb(III) quantitatively, even at a concentration of 1000 μg l−1, at pHs greater than two, and also, it reduces the initial concentrations of the transition metal ions to lower levels which can be tolerated in many studies. The adsorption of Sb(III) on mordenite follows the Freundlich isotherm and is endothermic in nature.Article Citation - WoS: 83Citation - Scopus: 97Characterization of the Uptake of Aqueous Ni2+ Ions on Nanoparticles of Zero-Valent Iron (nzvi)(Elsevier Ltd., 2009) Efecan, Nazlı; Shahwan, Talal; Eroğlu, Ahmet Emin; Lieberwirth, IngoThis study investigates the fixation of aqueous Ni2+ ions by nanoparticles of zero-valent iron (nZVI) prepared using the borohydride reduction method. The uptake of Ni2+ was tested under various experimental conditions like initial concentration, time, pH, and repetitive application of nZVI. Part of the experiments was devoted to comparing the extent of uptake of Ni2+ ions with those of Cu2+, Cd2+, Zn2+, and Sr2+ ions, which belong to a wide range of standard reduction potentials. Particle size analysis of nZVI in aqueous solution indicated that the material suffered extensive aggregation, much above the extent of aggregation known for dry nZVI. Nevertheless, nZVI showed fast uptake kinetics and very high uptake capacity. The overall results demonstrated the high fixation capability of nZVI towards the studied transition metal ions in aqueous solution. The same conclusion is, however, not valid for the removal of Sr2+ ions.Article Citation - WoS: 24Fiber Optic Sensors Using Novel Substrates for Hydrogen Sulfide Determination by Solid Surface Fluorescence(Elsevier Ltd., 2000) Eroğlu, Ahmet Emin; Volkan, Mürvet; Ataman, O. YavuzTwo different fiber optic sensors were developed for the determination of hydrogen sulfide at ppb concentration levels; a probe-type fiber optic sensor coated with polyethylene oxide containing 0.5 M CdCl2 and a fiber optic sensor utilizing 0.5 M CdCl2-pretreated filter paper as solid substrate. In the first type, CdCl2–polyethyleneoxide (PEO) mixture was coated onto the tip of a fiber optic probe and the probe was exposed to H2S. The methodology is based on the measurement of CdS fluorescence on the surface. Detection limit (3s) of the PEO-coated fiber optic system was 36.0 ppb for H2S and precision at the 0.552 ppm level was 29% R.S.D. For the fiber optic system utilizing CdCl2-pretreated filter paper, two different configurations were devised and evaluated; a bifurcated fiber optic sensor and a single fiber optic sensor. Similar figures were obtained with these two systems; the detection limit (3s) was 4.0 ppb for the bifurcated fiber optic sensor and 4.3 ppb for the single fiber optic sensor, and both sensors had linear responses in the range 0.032–1.0 ppm. Their precisions at 0.299 ppm level were also very similar, 10 and 11% R.S.D., respectively, for the bifurcated and single fiber systems. In addition to the fiber optic sensors developed, various surfactants (sodiumdodecylsulfate (SDS), Aerosol OT, Aerosol A102, Aerosol 501), some cellulosic substances (sodium carboxymethylcellulose (CMC), ethylcellulose, hydroxypropylmethylcellulose, ethylhydroxyethylcellulose, α-cellulose) and several water-soluble polymers (polyacrylicacid polyethleneoxide (PEO), polyvinylalcohol (PVA)) were dissolved in proper solvents and after mixing with 0.5 M CdCl2, were spread over glass slides. These novel solid substrates were exposed to H2S and fluorescence signal on the surfaces of the glass slides was measured with a luminescence spectrometer. The new substrates were shown to be good alternatives to filter paper for the determination of H2S by room temperature solid surface fluorescence spectrometry.
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