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Öğe A2BO4±? as New Materials for Electrocatalytic Detection of Paracetamol and Diclofenac Drugs(Springer, 2022) Zine, Amel; Ferkhi, Mosbah; Khaled, Ammar; Savan, Ebru KuyumcuIn this study, the electrochemical detection of drugs in the human body such as paracetamol and diclofenac was performed using the La2NiO4/carbon black and Pr2NiO4/carbon black electrocatalysts as sensor. The oxide materials were synthesized by the citrate method. The crystallinity of materials was determined by X-ray diffraction; the cell parameters and the crystallite size were calculated using the Debye-Scherrer formula. Morphology and grain size were determined by scanning electron microscope and the pore size was determined by the BET analysis. X-ray photoelectron spectroscopy analysis was used to evaluate the surface state of the synthesized oxide powders. Electrochemical characterization of the drugs on the electrocatalysts was carried out by cyclic voltammetry at different scanning speeds in a range of drug concentrations between 3 and 200 mu mol in a phosphate-buffered saline solution at pH 7. The square wave method was used to determine the detection limits. The synthesized nano-particle-based electrodes demonstrated excellent sensitivity in detecting drug/biomolecules (PCM and DIC) in biological fluids with the minimum detection limit 1.99 mu M and 2.32 mu M, respectively, at La2NiO4/carbon black electrode and 2.04 mu M and 2.37 mu M, respectively, at Pr2NiO4/carbon black electrode. The peak currents relative to the detection of the paracetamol and diclofenac drugs are respectively 800 and 1000 on La2NiO4/carbon black and 1000 and 500 mu A on Pr2NiO4/carbon black. This remarkable behavior enables us to propose these materials as alternative electrocatalysts that act as selective sensors for drug detection in the human body.Öğe Amperometric Simultaneous Measurement of Copper and Cobalt Ions with Polythiophene Incorporating Pendant Terpyridine Groups(Taylor & Francis Inc, 2014) Savan, Ebru Kuyumcu; Koytepe, Suleyman; Pasahan, Aziz; Erdogdu, Gamze; Seckin, TurgayTerpyridine containing thiophene monomer was synthesized. Electrochemical behavior of the monomer was studied by cyclic voltammetry. This monomer was polymerized via electrochemical methods and the resultant polymer was characterized. The stepwise fabrication process of the polymeric film electrode and its electrochemical sensing performance towards simultaneously Co and Cu ions were evaluated. The sensing parameters of the polymer electrode were investigated in detail, and the determination conditions were optimized. Under the optimal conditions, sensor response peak is linear to the Co ion concentration in the range of 1.0-50.0 mu M and the Cu ion concentration in the range of 1.0-20.0 mu M. Detection limit of terpyridine-based polythiophene film electrode for Co and Cu is respectively 100 nM and 0.05 nM.Öğe Antidepressant effect of Gentiana olivieri Griseb. in male rats exposed to chronic mild stress(Taylor & Francis Ltd, 2020) Berk, Ahmet; Yllmaz, Ismet; Abacioglu, Nurettin; Kaymaz, Mustafa Bahadir; Karaaslan, Merve Goksin; Savan, Ebru KuyumcuBackground: The flowering parts of Gentiana olivieri, known as 'Afat' in the southeastern Anatolia region of Turkey, are used as a tonic, an appetizer, and for the treatment of several mental disorders, including depression. The purpose of this study is to investigate the antidepressant effect of G. olivieri ethanol extract (GOEE) in a chronic mild stress-induced rat model, which was used to mimic a depressive state in humans, and to compare the effect with that of imipramine. Methods: Male Sprague-Dawley rats were randomly divided into six groups: control, stress, treated with imipramine (positive control) and treated with GOEE at three different (200, 500, 1000 mg/kg) doses groups. The rats in all groups, except the control group, were exposed to chronic mild stress. At the end of the 3-week experimental period, biochemical and behavioral parameters were examined. Results: The results showed that treatment with GOEE or imipramine significantly improved rats' sucrose consumption which was diminished by chronic mild stress, restored serum levels of corticosterone and proinflammatory cytokines (interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha)), prevented the increase of liver index of rats. Moreover, in the hippocampus tissue, decreased serotonin and noradrenaline levels were significantly increased by treatment with GOEE or imipramine, and antioxidant parameters (thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), and glutathione (GSH)) were significantly improved by treatment with GOEE though not with imipramine. Conclusion: The data demonstrate that G. olivieri may exert its antidepressant activity by improving monoaminergic system disorders, and by favorably affecting the antioxidant, inflammatory and the endocrine mechanisms.Öğe Application of Single-Walled Carbon Nanotube and Poly (3-Methylthiophene) Modified Sensors for Electrochemical Determination of Levodopa and Benserazide(Univ Tehran, Fac Chemistry, Center Excellence Electrochemistry, 2019) Savan, Ebru Kuyumcu; Erdogdu, GamzeSixteen electrochemical electrodes were prepared by modifying the electro-polymerized 3-methylthiophene to the below and above of the single-walled carbon nanotubes (SWCNTs) dispersion that dripped onto glassy carbon electrode. Determination of benserazide (BS) and levodopa (LD) in the presence of ascorbic acid (AA) was performed by differential pulse voltammetry (DPV) technique to find out which of these electrodes gave the best and fastest simultaneous response. The highest resolution and current densities were achieved with the electrode that 20 mu L 1.0% SWCNT was dribbled onto the bare electrode. The morphology and structure of modified electrode were characterized by scanning electron microscopy. Under optimum conditions AA, BS and LD gave sensitive oxidation peaks at nearly 90, 210 and 320 mV, respectively. The oxidation currents increased linearly with concentration of BS (50-100 mu M) and LD (5.0-9.5 mu M) in phosphate buffer solution (pH 7.0). The detection limits obtained by DPV were 3.0 mu M for BS and 1.1 mu M for LD. Additionally, the proposed modified sensor was applied successfully to biological fluids and tablet samples. The results proved that the modified sensor showed excellent selectivity, repeatability and reproducibility with high stability and accuracy.Öğe Determination of 3,4-dihydroxyphenylacetic acid in the presence of ascorbic acid and uric acid at poly(p-aminobenzene sulfonic acid) conducting polymer electrode(Springer, 2017) Savan, Ebru Kuyumcu; Erdogdu, GamzePoly(p-aminobenzene sulfonic acid) [poly(p-ABSA)] modified glassy carbon electrode (GCE) was used for the simultaneous determination of ascorbic acid (AA), 3,4-dihydroxyphenylacetic acid (DOPAC) and uric acid (UA). The polymer film was grown on GCE by the cyclic voltammetry method in the potential range from -1.5 to +2.5 V at a scan rate of 50 mV s(-1) for 14 cycles in 0.1 M KCl solution containing 5 mM p-ABSA. The anodic peaks for AA, DOPAC and UA at the poly(p-ABSA)/GCE were resolved in phosphate buffer solution (pH 7.0). On the other hand, the electro-oxidation peak current of AA, DOPAC and UA showed linear dynamic range, good stability and sensitivity. The linear range of DOPAC is over four orders of magnitude (R (2) = 0.998). The detection limit of DOPAC is 2.96 x 10(-7) mol L-1. The proposed method and electrode have been successfully applied for the determination of DOPAC in urine and blood serum samples and pharmaceutical tablets, demonstrating the stability and reliability of the proposed method and electrode.Öğe Determination of Antioxidant Properties and beta-Carotene in Orange Fruits and Vegetables by an Oxidation Voltammetric Assay(Taylor & Francis Inc, 2022) Koc, Tugca Bilenler; Savan, Ebru Kuyumcu; Karabulut, IhsanRecently, the evaluation of antioxidant properties using voltammetric techniques based on electrooxidation has attracted considerable attention. In this study, the antioxidant capacity, total phenolic compounds, and beta-carotene content of orange-fleshed fruits and vegetables, including carrots, persimmons, and pumpkins, were evaluated by standard and electrochemical methods. The antioxidant capacity, evaluated by the ABTS and DPPH measurements, and the total phenolic compounds were determined spectrophotometrically. The results were expressed as Trolox equivalent antioxidant capacity (TEAC) and gallic acid, respectively. The beta-carotene contents of the samples were determined by high-performance liquid chromatography (HPLC). Electrochemical measurements were performed with differential pulse voltammetry at a sensor formed by attaching single-walled carbon nanotubes onto the glassy carbon electrode surface. Trolox, gallic acid, and beta-carotene were determined electrochemically with high sensitivity, repeatability, and low detection limits. Regression analysis was performed to correlate the results of the spectrophotometric assays and HPLC with those obtained electrochemically and satisfactory results were obtained.Öğe Determination of Element Concentrations in Commercial Infant Formulas Using Atomic Absorption Spectrometry(Atomic Spectroscopy Press Ltd, 2017) Unuvar, Songul; Savan, Ebru Kuyumcu; Karaaslan, Nagihan M.The presence of heavy metals, inadequate minerals and elements in infant foods is of great concern. In this study, the heavy metals aluminum (Al) and lead (Pb), essential elements such as iron (Fe) and zinc (Zn), and minerals such as calcium (Ca), potassium (K), magnesium (Mg), and sodium (Na) were determined by atomic absorption spectrometry (AAS) in five different brands of 20 infant formula samples obtained from pharmacies and supermarkets in Malatya, Turkey. The Joint FAO/WHO Expert Committee on Food Additives GECFA) has set the maximum concentration levels of heavy metals in infant formula and levels of provisional tolerable weekly intake (PTWI) of these metals by infants. The levels of Al and Pb in the analyzed samples were found to be under legal limits. The recommended daily intake (RDI) of the essential elements and minerals were found within normal and permissible ranges, showing that the formulas are safe for infants.Öğe Electroanalytical determination of reduced-glutathione in biological samples(Derman Medical Publ, 2019) Savan, Ebru KuyumcuAim: In this study, it was aimed to determine the reduced Glutathione (GSH) at the modified sensor with a simple and reliable electroanalytical method. Material and Method: Cyclic voltammetry and differential pulse voltammetry techniques were used for the determination of reduced-GSH. And the modified sensor was fabricated by dropping single-walled carbon nanotube (SWCNT) dispersion onto the surface of the glassy carbon electrode. Results: The determination of reduced-GSH was accomplished at SWCNT modified sensor. The relationship between the current responses of the sensor and the concentrations of the reduced-GSH (1.0 x 10-(8) - 5.0 x 10-(8) M) showed excellent linearity and the detection limit was calculated as 75 nM. Discussion: Determination of trace amounts of reduced-GSH in urine samples was successfully applied at the modified sensor. The results showed that modification of the glassy carbon electrode with SWCNT could provide a new strategy for determining the concentration of GSH in physiological solutions.Öğe Electrochemical and in Silico Investigations of the Interaction between Nitro Blue Tetrazolium Chloride and Bovine Serum Albumin(Eurasia Acad Publ Group (Eapg), 2022) Kazici, Dilek; Alagoz, Mehmet Abdullah; Savan, Ebru KuyumcuThe binding ability of the drug on its interaction with the protein will also significantly affect the apparent volume of distribution of the drugs and, in many cases the rate of elimination of the drugs. The interactions of proteins and other molecules are a fascinating topic applied to surface technologies and sensors. Therefore, it is aimed to determine the NBTCand to elucidate its interaction with Bovine Serum Albumin (BSA) by electrochemical and in silico studies in this paper. The reduction in BSA oxidation signals measured by differential pulse voltammetry upon incubation with different NBTC concentrations indicated that NBTC was bound to BSA. In addition, in silico (molecular modeling and molecular dynamics) studies have been conducted on the interactions of NBTC with proteins in plasma. As a result of the in silico studies investigated the interactions of NBTC with serum albumin, its binding affinity, and the dynamic process in the binding state. In silico studies showed that NBTC binds to BSA with high affinity (with-7.986 kcal/mol docking score), and this binding was stable (with a 3.0 average RMSD value). Eventually, the results of the electrochemical and modeling studies were perfectly matched.Öğe Electrochemical and in silico study of the interaction between phenazopyridine and bovine serum albumin(Springer, 2024) Kazici, Dilek; Alagoez, Mehmet Abdullah; Savan, Ebru KuyumcuIn this study, an electrochemical sensor was developed using a simple methodology to investigate for the first time the interaction of phenazopyridine with bovine serum albumin (BSA). The modified sensor was fabricated by electropolymerized diphenylamine-4-sulfonic acid barium salt onto the glassy carbon electrode surface by the cyclic voltammetry technique. Very low detection limit and quantification limit values were obtained by differential pulse voltammetry (DPV) in 0.1 M NaClO4 as 0.13 mu M and 0.43 mu M, respectively. In addition, the interference effect was studied, and recovery studies were performed in urine samples achieving dramatic recovery values. Selective and reproducible determinations of phenazopyridine were performed perfectly with the developed sensor. The reduction in BSA oxidation signals as measured by DPV upon incubation with different phenazopyridine concentrations indicated that phenazopyridine was bound to BSA. The currents of the BSA peaks decreased linearly with the phenazopyridine concentration in the linear concentration range (2.00-22.60 mu M). The results of the DPV experiments showed the formation of the BSA-Phenazopyridine complex. Binding parameters such as binding constants and binding free energy were calculated with the voltammetric data. Molecular docking and molecular dynamics simulation studies were performed to learn more about the interaction mechanism between phenazopyridine and BSA. Residues in the active gorge of BSA playing an important role in binding were determined by in silico studies. In silico studies showed that phenazopyridine binds to BSA with high affinity and this binding was stable. Eventually, the results of the electrochemical and modeling studies were perfectly matched.Öğe Electrochemical biodetection of glucose using La0.6Sr0.4Co0.8Fe0.2O3 and La1,7Sr0,3CuO4 NanoParticles modified with black carbon deposited on glassy carbon electrode(Elsevier, 2023) Mekersi, Mouna; Ferkhi, Mosbah; Savan, Ebru KuyumcuNon-enzymatic developed biosensors, especially with noble nanoparticles received tremendous attention in the field of glucose molecule sensing. Herein low-cost, highly sensitive, and more effective nano-sized materials such as La1,7Sr0,3CuO4 and La0.6Sr0.4Co0.8Fe0.2O3 were synthesized by a simple citrate method, and modified with black carbon in purpose to use as electrodes for the simultaneous detection of glucose. The crystallite size, refinement, purity, shape, and morphology of nanomaterials were characterized using X-ray diffraction and Scanning Electron Microscopy techniques. Cyclic voltammetry, Differential Potential Voltammetry, Square Wave Voltammetry, and Electrochemical Impedance Spectroscopy techniques were used as investigative techniques. The modified electrodes showed excellent response and sensitivity for glucose molecule detection compared with previous literature, with a wide linear range from 0.1 M to 0.1 nM for La0.6Sr0.4Co0.8Fe0.2O3 and 0.1 M to 0.001 nM for La1,7Sr0,3CuO4, high sensitivities of 614.7 and 876.3 mu A.mM- 1.cm 2 and low detection limits of 0.972 nM and 0.0194 nM respectively. The performance of electrodes was checked by using real samples like synthetic urine and human blood. Both of the modified electrodes demonstrated satisfactory and reproducible results in real samples.Öğe Electrochemical determination of N-acetyl cysteine in the presence of acetaminophen at multi-walled carbon nanotubes and nafion modified sensor(Elsevier Science Sa, 2019) Savan, Ebru KuyumcuIn this study, an electrochemical sensor was used for simultaneously determination of N-acetyl cysteine (NAC) and acetaminophen (AC) using differential pulse voltammetry. Modification on the surface of a glassy carbon electrode (GCE) was carried out using multi-walled carbon nanotubes (MWCNTs) and Nafion (NF). The morphology and structure of the MWCNT-NF nanocomposites were characterised by scanning electron microscopy (SEM). The modified sensor showed excellent performance for the oxidation reactions of NAC and AC. Using the modified sensor, the oxidation peak potentials of NAC and AC were separated by a potential difference of 350 mV, while they were coincident at the bare electrode. Moreover, the current densities were significantly improved using the modified sensor. The modified sensor displayed a linear response range of 20-500 mu M NAC and the detection limit was 0.43 mu M (S/N = 3). Under optimal conditions, the modified sensor exhibited excellent stability and selectivity, with high precision and accuracy. With the satisfactory results obtained from the real samples analysis, the modified sensor can be used for routine analysis. To the best of our knowledge, this is the first study in the literature that detected NAC in the presence of AC at GCE/MWCNT-NF modified sensor.Öğe Electrochemical Determination of Norepinephrine at Poly (p-aminobenzenesulfonic Acid) Modified Sensor(Bentham Science Publ Ltd, 2020) Yagci, Sevket Zisan; Savan, Ebru Kuyumcu; Erdogdu, GamzeObjective: In this study, it was aimed to prepare an electrochemical sensor capable of assigning Norepinephrine in the presence of an interference such as ascorbic acid. Methods: A sensitive modified sensor was prepared by electrodeposition of p-aminobenzenesulfonic acid (p-ABSA) to the glassy carbon electrode by cyclic voltammetry. The electrooxidation of Norepinephrine was accomplished by cyclic and differential pulse voltammetry. Results: The current values were enhanced and the peak potentials of Norepinephrine and ascorbic acid were separated at the sensor compared to the bare electrode. There was linearity between the oxidation current and concentration of Norepinephrine ranging from 0.5 to 99.8 mu M in phosphate buffer solution at pH 7.0. The limit of detection was 10.0 nM and the sensitivity was 0.455 mu A/mu M. Conclusion: The determination of Norepinephrine was successfully performed in real samples such as blood serum and urine at the poly (p-ABSA) sensor. To the best of our knowledge, this is the first study to detect Norepinephrine in the presence of ascorbic acid at poly (p-ABSA) modified sensor in the literature.Öğe Electrochemical Determination of the Antioxidant Capacity, Total Phenolics, and Ascorbic Acid in Fruit and Vegetables by Differential Pulse Voltammetry (DPV) with a p-Toluene Sulfonic Acid Modified Glassy Carbon Electrode (TSA/GCE)(Taylor & Francis Inc, 2023) Koc, Tugca Bilenler; Savan, Ebru Kuyumcu; Karabulut, IhsanThe determination of antioxidant capacity, total phenolics, and ascorbic acid using accurate, efficient, low cost, and rapid methods has great analytical importance. The antioxidant capacity, total phenolics, and ascorbic acid content of apricots, arugula, banana, cranberries, spinach, and strawberries were investigated with an electrochemical approach and examined for compatibility with conventional methods. The antioxidant activity was determined by ABTS and DPPH assays. The total phenolic content was determined by the Folin Ciocalteu method and ascorbic acid was quantified by high-performance liquid chromatography (HPLC). In order to perform sensitive and simultaneous electrochemical measurements, the surface of a glassy carbon electrode (GCE) was modified by electropolymerization with p-toluene sulfonic acid (TSA). The TSA/GCE modified sensor was used for the first time for the determination of antioxidant capacity and total phenolic content. The surface of the modified sensor was characterized by cyclic voltammetry and scanning electron microscopy. The TSA/GCE was linearly correlated with the differential pulse voltammetry (DPV) for Trolox and gallic acid in 0.1M NaNO3 and ascorbic acid in pH 7.4 phosphate buffer. Electrochemical methods offer a promising alternative for the determination of antioxidant capacity and total phenolic content due to their simplicity, rapid response, low cost, sensitivity, and reproducibility.Öğe Electrochemical simultaneous determination of nitrate ions in water using modified glassy carbon electrode based on La1.7Sr0.3CuO4 and La0.6Sr0.4Co0.8Fe0.2O3 nanomaterials and black carbon sensors(Springer Heidelberg, 2024) Mekersi, Mouna; Savan, Ebru Kuyumcu; Ferkhi, MosbahNanoparticle-based materials have played an important role in the development of new electrochemical sensors and received recently tremendous attention for the detection of toxic ions such as nitrate molecules (NO3- and NO2-). Here, we employ La1.7Sr0.3CuO4 (LSCu) and La0.6Sr0.4Co0.8Fe0.2O3 (LSCF) low-cost, highly sensitive nanoparticles modified with black carbon as sensors for the detection of nitrate ions. The modified nanooxides were synthesized by a simple citrate method then prepared with black carbon powder and nafion solution as a sensing matrix on a glassy carbon electrode for the determination of nitrates ions in water using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy as electrochemical techniques. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for structural and morphological characterization. The calculated crystallite size d, using the Debye-Scherrer equation was found to be 325,193 nm for LSCu and 208,317 nm for LSCF by XRD technique. The grain sizes are, respectively, 47.80 nm and 65.05 nm which were extracted by SEM analysis. In this work, the modified sensors based on LSCu and LSCF demonstrate satisfactory response and sensitivities toward nitrate molecules compared with previous works. They characterized with very low detection limits of 0.0014 nM and 0.02 nM, high sensitivities of 58.8 and 57.3 mu A.mu M-1, respectively, and recorded a wide linear range from 1 M to 10(-12) M for LSCF and 4 M to 10(-13) M for LSCu. Both of the modified electrodes demonstrated excellent results in real river water sample with low detection limits of 3.1 nM for LSCu and 3.5 nM for LSCF and very good recoveries of 100.6% and 101.65%, respectively.Öğe Preparation and properties of selective polyurethane films and their use for the development of biomedical dopamine sensor(Taylor & Francis As, 2016) Savan, Ebru Kuyumcu; Pasahan, Aziz; Aksoy, Busra; Gungor, Oznur; Koytepe, Suleyman; Seckin, TurgayPolyurethane films were synthesized by 3,4-divanillyltetrahydrofuran and different diisocyanates. These prepared polyurethanes were characterized by FT-IR, DSC, DTA, and TGA techniques. For the amperometric applications, synthesized polyurethanes exhibited suitable T-g (degrees C), good thermal stability and good adhesive properties. In addition, because of their interesting film properties, attempts were made to prepare dopamine-sensing electrode. For this reason, selectivity of film-coated electrodes obtained from the chemically prepared polyurethanes toward electroactive and nonelectroactive species were examined by means of DPV technique. From the electrochemical results obtained, it has been demonstrated that the PU-1-coated electrode can be used for the development of biomedical sensor.Öğe Preparation of mesoporous carbon containing Polyurethane/Clay nanocomposite membrane based sensors for sensitive and selective determination of vitamin D2 in urine samples(Elsevier Sci Ltd, 2022) Savan, Ebru Kuyumcu; Ozcan, Imren; Koytepe, SuleymanMesoporous carbon containing polyurethane/clay membrane based sensors were produced for the rapid and sensitive electroanalytical determination of fat-soluble vitamin D2. Mesoporous carbon structures were prepared by the carbonization of bee pollens which were easily available in nature. These structures were combined with clay and polyurethane structures. The determination of vitamin D2 with modified electrodes was carried out by using square wave voltammetry in acetonitrile containing 0.1 M LiClO4. According to the response of modified electrode, a linear relationship was obtained between the anodic oxidation peak currents and concentrations of vitamin D2 in the linear concentration range (23 mu M - 844 mu M) with a low detection limit (0.73 mu M) was obtained. The sensitivity (4.65 mu A cm- 2 mu M- 1) and reproducibility (RSD%, 1.87 %) of the prepared novel sensor were found to be quite satisfactory. The proposed method and applicability of the electrode were tested in urine samples, achieving dramatic recovery values (99.99 %).Öğe Preparation of pyridoxine-based polyurethane modified sensors and their use in simultaneous determination of Cu(II) - Co(II) ions(Elsevier, 2024) Savan, Ebru Kuyumcu; Kazici, Dilek; Ozcan, Imren; Bayram, Songuel; Koytepe, SueleymanIn this study, pyridoxine-based polyurethane-modified electrodes were prepared to simultaneously and sensitively measure copper (Cu(II)) and cobalt (Co(II)) ions in complex matrix samples. For the production of the electrodes, firstly, the synthesis of pyridoxine-based polyurethane structures was carried out. In these syntheses, the polymer structure was diversified by using different isocyanates. Polyethyleneglycol-200 (PEG), pyridoxine (B6), and beta- cyclodextrin ( beta- CD) groups were used as the source of polyol. The synthesized polyurethane structures were characterized by different instrumental techniques and used in gold electrode surface modification. Modified sensor surfaces were examined by scanning electron microscopy and atomic force microscopy techniques. The prepared modified sensors were used for the simultaneous detection of Cu(II) and Co(II) ions using the differential pulse voltammetry technique. The limit of detection (LOD), limit of quantitation (LOQ), and R 2 values for Cu(II) ions were calculated as 8.81 mu M, 29.4 mu M, and 0.993, respectively. LOD, LOQ, and R 2 values for Co(II) ions were calculated as 9.84 mu M, 32.8 mu M, and 0.9935, respectively. For repeatability, the relative standard deviation (RSD %) of the prepared simultaneous sensors was determined as 1.54 and 1.71 for Cu(II) and Co(II), respectively. As a result, Cu(II) and Co(II) ions were measured independently and simultaneously with high sensitivity. According to these results, it is predicted that pyridoxine-based polyurethane-modified sensors may be suitable for the simultaneous detection of Cu(II) and Co(II) in medical, food, and agricultural samples.Öğe Simultaneous Electrochemical Detection of Estradiol and Testosterone Using Nickel Ferrite Oxide Doped Mesoporous Carbon Nanocomposite Modified Sensor(Electrochemical Soc Inc, 2020) Tanrikut, Emrullah; Ozcan, Imren; Sel, Evren; Koytepe, Sueleyman; Savan, Ebru KuyumcuEstradiol levels in women are related to lung, uterine (endometrial), ovarian and breast cancers, although the exact mechanism of cancer development is not fully understood. A new cost-effective sensor was fabricated by incorporating conductive NiFe2O4 metal oxide into the electrochemical sensitive platform of mesoporous carbon (MC) derived from cotton to measure estradiol determination by electrochemical methods. A new modified GCE/NiFe2O4-MC electrode, which exhibits electrocatalytic activities, was created by dropping NiFe2O4-MC onto the glassy carbon electrode (GCE) surface using the drop casting technique to detect the electroactive estradiol molecule. Estradiol was determined electrochemically by using the square wave voltammetry technique with a detection limit of 6.88 nM in 20.0-566 nM linear range in phosphate buffer solution at pH 7.4 with this novel modified GCE/NiFe2O4-MC electrode, that has the best electron transfer rate. The simultaneous determination of estradiol in the presence of testosterone was successfully performed in 0.1 M tetrabutylammonium tetrafluoroborate supportive electrolyte solution prepared in acetonitrile, an anhydrous medium. Real sample applications were carried out to prove the applicability and precision of the novelty-produced electrode. The amount of estradiol in tablet samples was obtained satisfactorily with high recovery values by standard addition method. (C) 2020 The Electrochemical Society (ECS). Published on behalf of ECS by IOP Publishing Limited.Öğe Square Wave Voltammetric (SWV) Determination of Quercetin in Tea Samples at a Single-Walled Carbon Nanotube (SWCNT) Modified Glassy Carbon Electrode (GCE)(Taylor & Francis Inc, 2020) Savan, Ebru KuyumcuThe voltammetric determination of quercetin in tea samples was performed at a modified sensor which was fabricated by the addition of a single-walled carbon nanotube dispersion on a glassy carbon electrode. Due to the electrochemcal activity of quercetin, electroanalytical methods were used with great success for the determination of quercetin. The electrochemical properties of quercetin were investigated. Quercetin in water and methanol extracts of tea samples were determined at the modified glassy carbon electrode by using square wave voltammetry. The results were found to be 116.4 and 116.3 mu g quercetin equivalent/g dry green tea, 127.9 and 104.24 mu g quercetin equivalent/g dry basil tea 27.5 and 26.1 mu g quercetin equivalent/g dry black tea. The limit of detection and limit of quantification values for quercetin for the 0.01 to 100 mu M concentration range were 7.7 nM and 25.6 nM, respectively. Very low concentrations of quercetin were successfully determined by square wave voltammetry with sensitivity and selectivity.
