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Bishkek, Kyrgyzstan

Ustundag Z.,Dumlupinar University | Caglayan M.O.,Cumhuriyet University | Guzel R.,Dicle University | Piskin E.,Hacettepe University | And 2 more authors.

The scope of this study is to modify a Surface Plasmon Resonance (SPR) sensor slide with isophthalic acid to evaluate the possible application on the detection of copper(ii) ions in aqueous media by total internal reflection ellipsometry. A gold sensor surface was modified by an electrochemical diazonium reduction modification method. The modified surfaces are characterized with cyclic voltammetry (CV) and ellipsometry. Isophthalic acid monolayer modified gold slides were used for in situ detection of aqueous Cu2+ solution with the SPR enhanced total internal reflection ellipsometry (SPRe-TIRE) technique. Layer formation, pH dependency of adsorption, sensor response of the SPRe-TIRE and isothermal kinetic parameters were examined. A high dependency on the number of CV cycles in the monolayer-multiple layer transition was observed. The suggested sensor gave a linear response over a wide range of Cu 2+ concentrations. It was also reported that adsorption on the SPRe-TIRE sensor gave Langmuir adsorption model behavior. © The Royal Society of Chemistry 2011. Source

Mulazimolu I.E.,University of Konya | Solak A.O.,Ankara University | Solak A.O.,Kyrgyz Turk Manas University
Analytical Methods

In this study, electrochemical modification of a glassy carbon (GC) electrode with apigenin was carried out and the modified electrode was used for determination of copper(ii) (Cu(ii)) in soil samples. The GC was modified through the electrochemical polymerization of apigenin (PolyApi/GC) on the electrode surface in aqueous media. The electrode surface was modified with apigenin in phosphate buffer solution (PBS), pH 7, from 0 mV to +1400 mV potential ranges, using 100 mV s -1 sweep rate and 30 cycles by cyclic voltammetry (CV). The surface characterizations of this sensor electrode were performed by CV, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Britton-Robinson (BR) buffer solution at pH 5 was used for determination of Cu(ii) by differential pulse voltammetry (DPV). The detection limit was obtained as lower as 1.0 × 10 -11 M. By using this calibration curve, the amount of Cu(ii) was determined as 7.34 × 10 -7 M in soil samples. The results showed that pH, incubation time and interferences of some cations and anions were significant. © 2011 The Royal Society of Chemistry. Source

Oztekin Y.,Selcuk University | Oztekin Y.,Vilnius University | Ramanaviciene A.,Vilnius University | Ryskevic N.,Vilnius University | And 5 more authors.
Sensors and Actuators, B: Chemical

This study reports the electrochemical modification of glassy carbon (GC) electrode surface with the electro-polymerized form of 1,10-phenanthroline monohydrate (PMH), the characterization of this polyphenanthroline modified electrode (PPMH/GC) and the electroanalytical application suitable for the determination of Cd(II) ions. The PPMH/GC electrode was characterized by cyclic voltammetry, chronoamperometry and atomic force microscopy and formation of polyphenanthroline layer grafted to surface of GC electrode was evidenced. Selectivity of PPMH/GC electrode towards heavy metal ions was investigated by square wave voltammetry. The PPMH/GC electrode was found to be suitable for selective determination of Cd(II) in the solutions containing the mixture of heavy metal ions and showed high stability and reproducibility. The analytical methodology was successfully applied for monitoring the toxic metal ions in real samples. © 2011 Elsevier B.V. All rights reserved. Source

Gupta V.K.,Indian Institute of Technology Roorkee | Gupta V.K.,Dr Rml Avadh University Faizabad | Yola M.L.,Sinop University | Yola M.L.,Hacettepe University | And 5 more authors.
Electrochimica Acta

Sulfisoxazole (SO) was grafted to glassy carbon electrode (GCE) via the electrochemical oxidation of SO in acetonitrile solution containing 0.1 M tetrabutylammoniumtetra-fluoroborate (TBATFB). The prepared electrode was characterized by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), reflection-absorption infrared spectroscopy (RAIRS) and X-ray photoelectron spectroscopy (XPS). The ellipsometric thickness of SO nanofilm at the glassy carbon surface was obtained as 14.48 ± 0.11 nm. The stability of the SO modified GCE was studied. The SO modified GCE was also utilized for the determination of Cd(II) ions in water samples in the presence of Pb(II) and Fe(II) by adsorptive stripping voltammetry. The linearity range and the detection limit of Cd(II) ions were 1.0 × 10-10 to 5.0 × 10-8M and 3.3 × 10-11M (S/N = 3), respectively. © 2013 Elsevier Ltd. All rights reserved. Source

Gupta V.K.,Indian Institute of Technology Roorkee | Yola M.L.,Sinop University | Yola M.L.,Hacettepe University | Atar N.,Dumlupinar University | And 3 more authors.
Electrochimica Acta

Graphene oxide (GO) based glassy carbon (GC) electrode has been prepared. Firstly, p-nitrophenyl (NP) modified GC (NP/GC) electrode was prepared via the electrochemical reduction of its tetraflouroborate diazonium salt. After the formation of NP/GC electrode, the negative potential was applied to NP/GC electrode to reduce the nitro groups to amine. p-Aminophenyl (AP) modified GC (AP/GC) electrode was immersed into a graphene oxide solution containing 1-ethyl-3(3-(dimethlyamino)propyl)-carbodiimide. Hence, we constructed GO terminated AP modified GC (GO/AP/GC) electrode. NP/GC, AP/GC and GO/AP/GC electrodes were characterized sequentially using cyclic voltammetry (CV) in the presence of 1.0 mM of potassium ferricyanide in 0.1 M KCl. In addition, GO and GO/AP/GC surfaces were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The GO/AP/GC electrode was used for the analysis of Cd(II) and Cu(II) ions by adsorptive stripping voltammetry. The linearity range and the detection limit of Cd(II) and Cu(II) ions were 1.0 × 10-11-5.0 × 10 -10 M and 3.3 × 10-12 M (S/N = 3), respectively. © 2013 Elsevier Ltd. All rights reserved. Source

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