Yazar "Dursun, Zekerya" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • [ X ]
    Öğe
    Glassy carbon electrode modified with poly-Neutral Red for photoelectrocatalytic oxidation of NADH
    (Springer Wien, 2011) Dilgin, Didem Giray; Gligor, Delia; Gokcel, H. Ismet; Dursun, Zekerya; Dilgin, Yusuf
    A new approach is described for the photoelectrocatalytic oxidation of Reduced -Nicotinamide Adenine Dinucleotide (NADH). It is based on a glassy carbon electrode (GCE) modified with a film of poly-Neutral Red (poly-NR) that is obtained by electropolymerization. Electrochemical measurements revealed that the modified electrode displays electrocatalytic and photo-electrocatalytic activity towards oxidation of NADH. If irradiated with a 250-W halogen lamp, the electrode yields a strongly increased electrocatalytic current compared to the current without irradiation. Amperometric and photo-amperometric detection of NADH was performed at +150 mV vs. Ag/AgCl/KClsat and the currents obtained are linearly related to the concentration of NADH. Linear calibration plots are obtained in the concentration range from 1.0 mu M to 1.0 mM for both methods. However, the slope of the current-NADH concentration curve of the photo-electrocatalytic procedure was 2-times better than that obtained without irradiation.
  • [ X ]
    Öğe
    Photoelectrocatalytic determination of NADH in a flow injection system with electropolymerized methylene blue
    (Pergamon-Elsevier Science Ltd, 2011) Dilgin, Yusuf; Dilgin, Didem Giray; Dursun, Zekerya; Gokcel, H. Ismet; Gligor, Delia; Bayrak, Burcu; Ertek, Bensu
    It was firstly described that a glassy carbon electrode electropolymerized with methylene blue shows an efficient photoelectrocatalytic activity towards NADH oxidation in a phosphate buffer solution (pH 7.0). In order to perform the photoelectrocatalytic determination of NADH in a flow injection analysis (FIA) system, a home-made flow electrochemical cell with a suitable transparent window for the irradiation of the electrode surface was constructed. The currents obtained from the photoamperometric measurements in the FIA system at optimum conditions (flow rate of carrier solution, 1.3 mL min(-1): transmission tubing length, 10 cm; injection volume, 100 mu L; and constant applied potential, +150 mV vs. Ag/AgCl) were linearly dependent on the NADH concentration and linear calibration curves were obtained in the range of 1.0 x 10(-7)-2.0 x 10(-4) M. The detection limit was found to be 4.0 x 10(-8) M for photoamperometric determination of NADH. (C) 2010 Elsevier Ltd. All rights reserved.
  • [ X ]
    Öğe
    Photoelectrocatalytic oxidation of NADH in a flow injection analysis system using a poly-hematoxylin modified glassy carbon electrode
    (Elsevier Advanced Technology, 2010) Dilgin, Didem Giray; Gligor, Delia; Gokcel, H. Ismet; Dursun, Zekerya; Dilgin, Yusuf
    A stable electroactive thin film of poly-hematoxylin (poly-HT) was successfully prepared on a glassy carbon electrode (GCE) surface by recording successive cyclic voltammograms of 0.3 mM HT, in a phosphate buffer solution (pH 7.0) containing 0.1 M NaNO3, in the potential range of -0.5 to +2.0 V vs. Ag/AgCl. The deposition of HT on GCE surface can be explained through the electropolymerization process. This poly-HT modified electrode exhibited a good electrocatalytic activity towards the NADH oxidation in a phosphate buffer solution (pH 7.0), and led to a significant decrease in the overpotential by more than 320 mV compared with the bare GCE. In order to perform the photoelectrocatalytic determination of NADH in a flow injection analysis (FIA) system, a home-made flow electrochemical cell with a suitable transparent window for irradiation of the electrode surface was constructed. Flow rate of carrier solution, transmission tubing length, injection volume and applied potential for the amperometric and photoamperometric FIA studies were optimized as 1.3 mL min(-1),10 cm, 100 mu L and +300 mV vs. Ag/AgCl, respectively. The currents obtained from amperometric and photoamperometric measurements in FIA system at optimum conditions were linearly dependent on the NADH concentration and linear calibration curves were obtained in the range of 1.0 X 10(-7)-1.5 X 10(-4) M and in the range of 1.0 x 10(-7)-2.5 X 10(-4) M NADH, respectively. The relative standard deviation (RH)) of six replicate injections of 6.0 x 10(-5) M NADH was calculated as 2.2% and 4.3% for the amperometric and the photoamperometric method, respectively. The limit of detection was found to be 3.0 x 10(-8) M for the photoamperometric determination of NADH. (C) 2010 Elsevier B.V. All rights reserved.