Yazar "Erdogdu, Gamze" seçeneğine göre listele

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    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, Turgay
    Terpyridine 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.
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    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, Gamze
    Sixteen 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.
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    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, Gamze
    Poly(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.
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    Electrochemical Determination of Norepinephrine at Poly (p-aminobenzenesulfonic Acid) Modified Sensor
    (Bentham Science Publ Ltd, 2020) Yagci, Sevket Zisan; Savan, Ebru Kuyumcu; Erdogdu, Gamze
    Objective: 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.
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    Investigation of them voltammetric characteristics of poly (1,4-diaminobenzene) film as a dopamine-selective polymer electrode
    (Tubitak Scientific & Technological Research Council Turkey, 2007) Erdogdu, Gamze; Karagozler, A. Ersin
    Electrochemical polymerization of 1,4-diaminobenze tie in the KCl aqueons electrolyte at a potential of 0.600 V versus Ag/AgCl produces adherent poly(1,4-diaminobenzene) film on a gold electrode. The electrochemical behavior of dopamine and ascorbic acid at the polymer electrode prepared in this manner was examined by cyclic and differential pulse voltammetry. Voltammetry studies showed that polymeric film with a thickness corresponding to a 7-mC charge exhibited selective. permeation for dopamine while retaining ascorbic acid. All the polymerization parameters affecting the permselective characteristics were systematically investigated and the optimum values were determined. The results showed that a polymeric membrane, owing to its permselective character, could be used as a dopamine-selective membrane.
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    Selective detection of dopamine with poly(diphenylamine sulfonic acid) modified electrode in the presence of ascorbic acid
    (Maik Nauka/Interperiodica/Springer, 2011) Mutlu, Mehmet Mutluhan; Erdogdu, Gamze
    A glassy carbon electrode was modified with electropolymerized film of diphenylamine sulfonic acid (DPASA). Electropolymerization was performed by cyclic voltammetry in 0.1 M KCl solution. The modified electrode showed an excellent electrocatalytic effect towards oxidation of dopamine (DA) and ascorbic acid (AA). Electrostatic interaction between the negatively charged poly(DPASA) film and either cationic DA species or anionic AA species favorably contributed to the redox response of DA and AA. Anodic peaks of DA and AA in their mixture were well separated by ca 168 and -11.8 mV. The proposed modified electrode was utilized for selective determination of dopamine in the concentration range of 5.0 x 10(t7)-2.0 x 10(-5) M in the presence of high concentration of ascorbic acid. Detection limit was 6.5 x 10(-9) M.
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    Voltammetric Determination of 5-Hydroxyindoleacetic Acid at Poly (p-amino benzene sulfonic acid) Modified Sensor
    (Univ Tehran, Fac Chemistry, Center Excellence Electrochemistry, 2022) Yilmaz, Abidin; Savan, Ebru Kuyumcu; Erdogdu, Gamze
    In this study, the quantitative amount of 5-hydroxyindoleacetic acid (5-HIAA) was determined at poly (p-amino benzene sulfonic acid) (p-ABSA) modified glassy carbon electrode. The redox property of 5-HIAA was investigated by cyclic voltammetry. The cyclic voltammograms showed that the redox reaction of 5-HIAA was irreversible. Scan rate study showed that the redox reaction of 5-HIAA was controlled by both diffusion and adsorption on the poly (p-ABSA) modified sensor. Differential pulse voltammetry technique was used for the quantitative analysis of 5-HIAA in phosphate buffer solution at pH 7.00. The linear working range of the calibration graphs was determined as 1x10(-5)-9x10(-5) M (R-2, 0.9912), and the detection limit was determined as 5.3x10(-7) M. Recovery values in the analysis of urine samples were between 99.4% and 103.0%. The results showed that the modified sensor can be applied to the determination of 5-HIAA in the presence of ascorbic acid. The proposed sensor is promising for routine analysis due to its high selectivity, reproducibility, long-term stability, and high recovery values in biological samples.