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Öğe Electrochemical determination of ceftriaxone using polyurethane-modified electrode containing caffeic acid and chitosan(Taylor & Francis Inc, 2022) Hassine, Chedia Ben Ali; Gungor, Oznur; Burc, Muammer; Ozcan, Imren; Koytepe, Suleyman; Duran, Serap TitretirThe aim of this work was to develop an electrochemical sensor based on caffeic acid and chitosan-containing polyurethane (CAC-PU) films modified platinum electrode for ceftriaxone (CFX) determination. For this aim, firstly the CAC-PU structures were synthesized from three different diisocyanates and these structures were characterized with spectroscopic, thermal and surface analysis techniques. Then, these CAC-PU structures were coated on bare Pt electrode surface for the preparation of CFX selective sensors. Throughout this study several analytical parameters, such as film thickness, electrolyte type, pH effect, and scan rate were investigated by using differential pulse voltammetry (DPV) method. Under the optimized conditions, the voltammetric test results showed best analytical performances for CFX detection with a linear range from 0.1 to 1.5 mM. Limit of detection (LOD) and correlation coefficient (R-2) were obtained 52 mu M and 0.9991 using CAC-PU modified electrode, respectively. Stability of the modified electrode was found to be 96.78% by using reproducibility experiments (n = 10). Applicable of the presented sensor was tested in two synthetic urine samples and recoveries values were obtained 98.7% and 110%, respectively. The prepared modified electrode exhibits high repeatability, fast response, and high sensitivity, which makes it suitable for the detection of CFX in urine samples.Öğe A new voltammetric sensor for penicillin G using poly (3-methylthiophene)-citric acid modified glassy carbon electrode(Elsevier Science Sa, 2022) Gungor, Oznur; Burc, Muammer; Hassine, Chedia Ben Ali; Koytepe, Suleyman; Duran, Serap TitretirIn this study, an effective voltammetric sensor was developed for determination of penicillin G by electro-polymerization of 3-methylthiophene with citric acid on glassy carbon electrode. Penicillin G selective electrode was prepared in water:acetonitrile (1:1) mixture containing 0.1 M sodium perchlorate as electrolyte medium with cyclic voltammetry. Then, the electrochemical behavior of penicillin G on poly(3-methylthiophene) based membrane modified electrode was investigated by cyclic voltammetry, differential pulse voltammetry and differential pulse stripping voltammetry techniques. When the penicillin G responses of the modified glassy carbon electrode were compared with the bare glassy carbon electrode responses, it was seen that the selectivity and sensitivity of the penicillin G responses of the modified electrode significantly increased. A linear calibration graph for penicillin G was obtained in the concentration range of 0.07 to 4.0 mM with the prepared electrode. The R2 value was calculated as 0.9999 from the linear calibration curve. The limit of detection and limit of quantitation of the poly(3-methylthiophene)-citric acid modified glassy carbon electrode for penicillin G were calculated as 8 mu M and 28 mu M, respectively. In addition, the developed electrode for the detection of PeG was applied to milk samples. The recovery efficiency of the poly(3-methylthiophene)-citric acid modified glassy carbon electrode was obtained in the range of 93 % and 103 % for three different milk samples. As a result; the modified electrode can be used for residue penicillin detection in food and biological samples.Öğe Preparation of Molecularly Imprinted Metoprolol Sensor from Poly(aniline-co-p-toluene sulfonic acid)(Univ Tehran, Fac Chemistry, Center Excellence Electrochemistry, 2022) Gungor, Oznur; Hassine, Chedia Ben Ali; Burc, Muammer; Koytepe, Suleyman; Duran, Serap TitretirIn this study, the metoprolol (MTP), which is a beta-blocker class molecule used in hypertension treatment, was determined by modifying the glassy carbon electrode (GCE) with a molecular imprinting technique. Firstly, p-toluene sulfonic acid (PTSA) and aniline (AN) were co-electropolymerized in the presence of MTP as a template molecule on GCE and MTP contained poly(aniline-co-p-toluene sulfonic acid) (p(AN-co-PTSA)) film was obtained. Then, the template metoprolol molecule was desorbed from the conductive p(AN-co-PTSA) film structure on the GCE surface using hydrochloric acid. Obtained molecularly imprinted electrodes were used to determine MTP by the square wave voltammetry (SWV) method. The modified electrodes obtained showed a correlation coefficient (R-2) of 0.9995 in the 40-1500 mu M MTP concentration range. The limit of detection (LOD) and the limit of quantification (LOQ) of the p(AN-co-PTSA) film modified MTP electrodes were 37.9 mu M and 126.3 mu M, respectively. A standard deviation of 1.33% was observed for the first three replicates with the same modified electrode. For the time reproduced electrodes, stable reproducibility was achieved between the first electrode result and the tenth electrode result. For the modified MTP electrode, the relative standard deviation (RSD%) value was calculated to be 2.53%. As result, the molecularly imprinted electrodes prepared with p(AN-co-PTSA) film have low response time, high reproducibility, good stability, and high selectivity for the determination of MTP.Öğe Voltammetric Determination of ?-Lipoic Acid using Poly(Vanillin) Modified Platinum Electrode(Univ Tehran, Fac Chemistry, Center Excellence Electrochemistry, 2020) Duran, Serap Titretir; Hassine, Chedia Ben Ali; Burc, Muammer; Gungor, OznurIn the present study electrochemical detection of alpha-lipoic acid (alpha-LA) was carried out with a poly(Vanillin) modified platinum electrode p(VA)/PtE in Brinton Robinson buffer (BR) solution. The platinum electrode surface's was modified with cyclic voltammetry method. The prepared Pt electrode was characterized by cyclic voltammetry in ferrocyanide and scanning electron microscopy (SEM) images. The number of cycles and scan rate effects were studied using square wave voltammetry (SWV) in BR buffer containing 1 mM alpha-LA. The electrochemical oxidation of alpha-lipoic acid on the modified Pt electrode is influenced by the pH and it is an irreversible reaction in which one electron and one proton are transferred. Electrolyte type and pH effect were studied. The anodic peak current shows a linear increase with alpha-LA concentrations ranging from 0.03 mM to 2.00 mM at pH 5, the detection limit being of 0.025 mM. The alpha-lipoic acid quantification in synthetic urine samples was made by SWV with the modified Pt electrode.Öğe VOLTAMMETRIC DETERMINATION OF RESVERATROL USING POLY(L-PHENYLALANINE)-MODIFIED GOLD ELECTRODE(Soc Chemists Technologists Madeconia, 2020) Gungor, Oznur; Hassine, Chedia Ben Ali; Burc, Muammer; Duran, Serap TitretirIn this study, we investigated the electrochemical modification of a gold electrode using poly(L-phenylalanine) and its applicability for the quantification of resveratrol (RESV). The gold electrode was modified with L-phenylalanine employing cyclic voltammetry (CV) in aqueous solution. The detection of RESV with the modified electrode was investigated by square wave voltammetry (SWV) in a phosphate buffer solution (PBS) (pH = 1.2). The analytical calibration curve for RESV showed a linear response with concentration in the oxidation peak current range from 50 to 1000 mu M, with a limit of detection (LOD) of 35.16 mu M and limit of quantitation (LOQ) of 105.5 mu M. The application of the prepared electrochemical sensor was carried out with a standard addition method in red wine samples.
