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Öğe A deep eutectic solvent based liquid phase microextraction for the determination of caffeine in Turkish coffee samples by HPLC-UV(Taylor & Francis Ltd, 2020) Sivrikaya, SezenA novel liquid-phase microextraction procedure for the determination and extraction of caffeine using a deep eutectic solvent based liquid-phase microextraction method (DES-LPME) was developed. A deep eutectic solvent consisting of choline chloride-phenol (1:3) and tetrahydrofuran as a dilution solvent were used for the extraction of caffeine from Turkish coffee samples. The quantitative recoveries were obtained when the DES volume was 400 mu L, and the volume of tetrahydrofuran that was used as an emulsifier solvent was 800 mu L. The limit of detection and the limit of quantification were found to be 0.12 and 0.40 mu g mL(-1), respectively. Linear dynamic range was 0.5-100 mu g mL(-1), and coefficient of determination (R-2) was 0.9998. The relative standard deviation (RSD) was 2.20% when the standard solution concentration was 1.0 mu g mL(-1). The fact that the determination coefficient obtained from the calibration curve was greater than 0.9998 gives information about the accuracy of the method. Also, in order to determine the accuracy of the developed method, selected coffee samples were spiked with 25 and 50 mu g mL(-1) caffeine.Öğe Novel Functionalized Silica Gel for On-line Preconcentration of Cadmium(II), Copper(II), and Cobalt(II) with Determination by Flame Atomic Absorption Spectrometry(Taylor & Francis Inc, 2016) Sivrikaya, Sezen; İmamoğlu, Mustafa; Yıldız, Salih Zeki; Kara, DeryaSilica gel functionalized with 2-[N,N'-bis(2,3-dihydroxybenzaldimin)] aminoethylamine was employed as a novel sorbent for preconcentration of copper(II), cobalt(II), and cadmium(II) by flow injection-solid phase extraction. The pH of the analyte solution, sample and eluent flow rate, eluent volume, and the presence of concomitant ions were optimized. The limits of detection were 0.65, 0.52, and 1.42 mu g/L and preconcentration factors were 12.3, 21.5, and 7.31 for cadmium(II), copper(II), and cobalt(II), respectively. The adsorption capacities of the functionalized silica gel for cadmium(II), copper(II), and cobalt(II) ions were 41.1, 31.7, and 26.5mg/g. The preconcentration method was validated by determination of cadmium(II), copper(II), and cobalt(II) levels in Virginia Tobacco Leaves (CTA-VTL-2) and Water-Trace Elements (NWTM-15.2) certified reference materials. The method was also used to analyze water and food samples, and offers simplicity, reproducibility, high recovery, rapid and automated analysis, favorable ease of use, and low detection limits.Öğe A novel vortex-assisted liquid phase microextraction method for parabens in cosmetic oil products using deep eutectic solvent(Taylor & Francis Ltd, 2019) Sivrikaya, SezenThe parabens, which are harmful to our bodies, are primarily utilized as preservatives in medicine, personal care products and cosmetics. A novel, more efficient, fast and cheap vortex-assisted liquid phase microextraction method based on deep eutectic solvents (DESs) was developed for the determination of parabens. The microextraction conditions were optimized using these solvents and the analytical parameters of the method were determined under optimal microextraction conditions. After extraction, the chromatographic separation of parabens was undertaken using high-performance liquid chromatography-UV detection. Experimental parameters, such as DES type, DES volume, dilution solvent volume and vortex extraction time were optimized. DES6 [ChCl-Ethylene glycol (1/2)] was the most suitable DES to work in this study. Detection limits for this method of 0.053 mu g mL(-1) for methylparaben, 0.061 mu g mL(-1) for ethylparaben, 0.049 mu g mL(-1) for propylparaben and 0.052 mu g mL(-1) for butylparaben were obtained. Correlation coefficients (R-2) for a concentration range of 0.1-100 mu g mL(-1) were higher than 0.9992 and relative standard deviation (RSD) values below 2.91% at parabens concentration of 2.5 mu g mL(-1) were obtained. The results of spike/recovery values of real samples were greater than 84%. When compared with other methods, the main advantages include lower LOD, short extraction time, rapidity, repeatability and simplicity.Öğe On-line Preconcentration of Pd(II) Using Polyamine Silica Gel Filled Mini Column for Flame Atomic Absorption Spectrometric Determination(Springer International Publishing Ag, 2017) Sivrikaya, Sezen; Karslı, Bülent; İmamoğlu, MustafaIn this study, a novel method for determination of Pd(II) ions at trace level was developed using on-line preconcentration onto polyamine group bonded silica (PA-SG) with flame atomic absorption spectrometric determination. Pd(II) uptake dynamics of PA-SG was studied batchwise by investigating acidity and chloride concentration of aqueous phase, contact time and initial concentration of Pd(II) ions. The Pd(II) adsorption capacity of PA-SG was found to be 158.7 mg g(-1) from aqueous phase containing 0.1 M HCl. The on-line preconcentration procedure of Pd(II) was optimized with main analytical parameters including sample and eluent flow rate, eluent type and volume and matrix ions. The optimum eluent type and flow rate of sample and eluent were found to be 1.0% thiourea in 1.0 mol L-1 HCl and 7.5 mL min(-1), respectively. The preconcentration factor and sampling frequency were calculated to be 23.9 and 20 h(-1), respectively. The calibration graph was linear over the range 10-200 mu g L-1. The limits of detection (3 sigma) and quantification (10 sigma) values were computed to be 3 mu g L-1 and 10 mu g L-1, respectively. The RSD, % was found to be 4.6% for five measurement of 25 mu g L-1 of Pd(II) ions. The accuracy of the developed method was successfully checked by determination of Pd(II) level of certified reference material platinum ore (SARM 7B). The proposed method was successfully applied for Pd(II) determination in various environmental water samples such as river, lake, sea and tap water, and spent auto catalyst.Öğe Online Solid-Phase Extraction of Cd(II), Cu(II), and Co(II) Using Covalently Attached Bis(salicylaldimine) to Silica Gel for Determination in Food and Water by Flame Atomic Absorption Spectrometry(Taylor & Francis Inc, 2018) Sivrikaya, Sezen; İmamoğlu, MustafaIn this study, a novel sorbent material bearing a bis(aldimine) group was designed and successfully synthesized by covalently bonding a 2-[N,N-bis(salicylaldimine)]aminoethyl amine ligand to the silica gel surface that was characterized by carbon, hydrogen, and nitrogen elemental analysis, thermogravimetric analysis, and the Fourier transform infrared spectroscopy technique. The sorbent was used for the online solid-phase extraction (SPE) of Cd(II), Cu(II), and Co(II) ions for their determination at trace concentration levels by flame atomic absorption spectrometry. The effective factors for the online SPE such as the pH and the flow rate of the sample solution, and type, volume, and flow rate of eluent were investigated. The concentration levels of Cd(II), Cu(II), and Co(II) were measured in certified reference materials including Virginia tobacco leaves (CTA-VTL-2) and water-trace elements (NWTM-15.2) to validate this method. The metal levels in environmental water were determined by this method, and the values were checked by spiking and recovery experiments and independent analysis by inductively coupled plasma-mass spectrometry. The adsorption capacities of the sorbent were found to be 41.2, 31.6, and 25.6mg/g for Cd(II), Cu(II), and Co(II), respectively. This method was also successfully used for the determination of Cd(II), Cu(II), and Co(II) concentrations in rice and molasses.Öğe Preparation of Cerium Oxide Nanoparticles: An Efficient Catalyst to the Synthesis of Dimeric Disulphide Schiff Bases(2017) Durmuş, Sefa; Dalmaz, Aslıhan; Özdinçer, Mesut; Sivrikaya, SezenDimeric disulphide Schiff bases were synthesized via reactions of 2,2’-diaminodiphenyl disulphide with various aromatic aldehydes under reflux and prepared nano?sized cerium oxide as catalyst. It was observed that, when nanocatalyst was used, the catalyst could be reduced the reaction time and increased yields compared with the none-catalyst conditions. Moreover, the CeO2 nanocatalyst was easy preparation, non-hazardous, ecofriendliness and low cost. The morphological features of CeO2 nanocatalyst were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX). The structures of ligands were illuminated some techniques such as fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR) spectroscopy and thermogravimetric analysis (TGA) / differential thermal analysis (DTA)Öğe Synthesis of Nano Poly(2-thiophenecarboxaldehyde) and Characterization of Structure(2018) Sivrikaya, Sezen; Dalmaz, Aslıhan; Durmuş, SefaThis article describes a chemical oxidative polymerization for the preparation of nano polymeric thiopheneby using FeCl3 as oxidant. 2-thiophenecarboxaldehyde (2-THCA) compound was used as a monomer atthis polymerization process. The structure of synthesized nano polymeric thiophene was confirmed byscanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), thermogravimetricanalysis (TGA), raman spectroscopy, and elemental analysis of C, H, O and S. SEM images showed thatthe poly(2-thiophenecarboxaldehyde) (PTHCA) was synthesized in nanoscale and had a homogeneous andsmooth structure. The size of the synthesized nano particles was not more than 35 nm. Thermal analysis ofnano polymeric thiophene showed that the polymer is thermally stable up to 450-460 oC. When elementalanalysis results of PTHCA were examined, it was seen that the obtained data after the synthesis of nanopolymeric thiophene and the theoretically determined data were agree with each other.Öğe Use of ion chromatography method on the determination of some anions in the water collected from Sakarya, Turkey(Acg Publications, 2019) Altundağ, Hüseyin; Ağar, Şerife; Altıntığ, Esra; Ateş, Asude; Sivrikaya, SezenIn this study simultaneous analysis of seven different anions (Fluoride, Chloride, Bromide, Nitrite, Nitrate, Phosphate, and Sulfate) in13 different water samples collected from Sakarya/Turkey and it was conducted with ion chromatography method. Analyzes were performed simultaneously using the ion chromatography method. Some validation tests and the optimum conditions for the determination of anions were studied. The analysis of anions was accomplished by the dilution of the sample injection device. Samples were used to adjust the terms of the device and the results were recorded. Ion chromatography (IC) is now considered as an excellent technique for the analysis of ions in many samples.
