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    Analysis of the Nano-Surface of a Modified Glassy Carbon Electrode by Pseudo Phase Plane Method
    (Amer Scientific Publishers, 2011) Tenreiro Machado, J. A.; Baleanu, Dumitru; Dinc, Erdal; Solak, Ali Osman; Eksi, Haslet; Guzel, Remziye
    This paper presents the Pseudo phase plane (PPP) method for detecting the existence of a nanofilm on the nitroazobenzene-modified glassy carbon electrode (NAB-GC) system. This modified electrode systems and nitroazobenze-nanofilnn were prepared by the electrochemical reduction of diazonium salt of NAB at the glassy carbon electrodes (GCE) in nonaqueous media. The IR spectra of the bare glassy carbon electrodes (GCE), the NAB-GC electrode system and the organic NAB film were recorded. The IR data of the bare GC, NAB-GC and NAB film were categorized into five series consisting of FILM1, GC-NAB1, GC1; FILM2, GC-NAB2, GC2; FILM3, GC-NAB3, GC3 and FILM4, GC-NAB4, GC4 respectively. The PPP approach was applied to each group of the data of unmodified and modified electrode systems with nanofilm. The results provided by PPP method show the existence of the NAB film on the modified GC electrode.
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    Characterization Approach to Modified Glassy Carbon Electrode-Nanofilm System Within Multidimensional Scaling
    (Amer Scientific Publishers, 2011) Tenreiro Machado, J. A.; Baleanu, Dumitru; Dinc, Erdal; Solak, All Osman; Eksi, Haslet; Guzel, Remziye
    The aim of this work is to characterize the nanofilm consisting of the benzoic acid-modified glassy carbon (GC) electrode system through multidimensional scaling space analysis. The surface modification is based on the electrochemical reaction between the GC electrode and benzoic acid-diazonium salt (BA-DAS). As a result, the nonofilms regarding the benzoic acid-glassy carbon (BA-GC) electrode surface was obtained. For the analysis of the naonfilm of BC-GC electrode system, the IR spectra of the modified BA-GC electrode surface, GC surface and BA-DAS were recorded in the spectral range of 599.84 - 3996.34 [cm(-1)]. The IR data vectors of the above three forms were processed by the using the multidimensional scaling space approach to demonstrate the existence of a nanofilm on the modified BA-GC electrode system. Two- and three-dimensional MDS profiles obtained by application of multidimensional scaling approach to the data sets {CG1, ... ,CG10}, {BA-GC1, ... ,BA-GC10} and {FILM1, ... ,FILM10} allow a good recognition of the nanofilm on the modified glassy carbon (GC) electrode system.
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    Determination of Acetaminophen in Commercial Formulations Using Silver Nanostructured Aniline Modified Pencil Graphite Electrode
    (Electrochemical Soc Inc, 2013) Guzel, Remziye; Eksi, Haslet; Dinc, Erdal; Solak, Ali Osman
    A nanostructured silver-aniline modified pencil electrode obtained by applying experimental design and optimization was developed for the differential pulse stripping voltammetric quantification of acetaminophen in the pharmaceutical products, tablet and syrup. The electrode development process was performed by the modification of PGE with aniline using CV procedure and the reduction of silver nanoparticle on the polyaniline modified PGE. As a result, a new electrode system consisting of a nanostructured silver-polyaniline modified pencil graphite electrode (AgNS-PA-PGE) was obtained to reach a well-defined and higher peak current for the analysis of the related drug. The calibration curve was found linear in the range of 5 x 10(-8)-8 x 10(-7) M for acetaminophen. The validity and applicability of the proposed voltammetric method was tested by analyzing independent validation samples. It was observed that the proposed voltammetric approach for the real tablet and syrup samples gave successful analysis results. (C) 2013 The Electrochemical Society. All rights reserved.
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    Effect of Au and Au@Ag core-shell nanoparticles on the SERS of bridging organic molecules
    (Academic Press Inc Elsevier Science, 2010) Guzel, Remziye; Ustundag, Zafer; Eksi, Haslet; Keskin, Selda; Taner, Bilge; Durgun, Zeynep Gulsah; Turan, Aybuke A. Isbir
    Gold nanoparticles (AuNPs) with about 6 nm size were produced and stabilized with mercaptopropionic acid (MPA) film to produce a monolayer protected cluster (MPC) of AuS(CH2)(2)COOH. 4-Aminothiophenol (ATP) molecules were introduced to the activated carboxylic acid ends of the film surrounding the AuNPs to produce AuS(CH2)(2)CONHPhSH MPC. These modified AuNPs were again self-assembled with Au@Ag core-shell bimetallic nanoparticles via the -SH groups to produce an organic bridge between Au and Au@Ag metallic nanoparticles. An unusually strong enhancement of the Raman signals was observed and assigned to the plasmon coupling between the AuNPs and Au@Ag NPs bridged assembly. Formation of AuS(CH2)(2)COOH and AuS(CH2)(2)CONHPhSH clusters and AuS(CH2)(2)CONHPhS(Au@Ag) assembly is confirmed by UV-Vis, reflection-absorption IR spectroscopy (RAIRS) and X-ray photoelectron spectroscopy (XPS), as well as by TEM analysis. The SERS activity of the AuNPs and Au@Ag NPs was tested using the HS(CH2)(2)CONHPhSH molecule as a probe to compare the effectiveness of monometallic and bimetallic systems. SERS spectra show that Au@Ag bimetallic nanoparticles are very effective SERS-active substrates. (C) 2010 Elsevier Inc. All rights reserved.
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    Factor Analysis for the Characterization of the Nano-Surface of the Nitroazobenzene-Modified Glassy Carbon Electrode
    (Amer Scientific Publishers, 2012) Dinc, Erdal; Baleanu, Dumitru; Solak, Ali Osman; Eksi, Haslet; Guzel, Remziye
    Factor analysis with orthogonal varimax rotation was applied to determine the existence of a nano-structure on the nitroazobenze-modified glassy carbon electrode (NAB-GC) system. The NAB-GC electrode systems and benzoic acid-nanofilm (NAB-FILM) were obtained by using the electrochemical surface modification experiments. The IR spectra of the bare glassy carbon electrodes (GC), the NAB-GC electrode system and NAB-FILM were recorded. The IR data of the bare GC, BA-GC and BA-FILM were categorized into five series consisting of FILM1, GC-NAB1, GC1; FILM2, GC-NAB2, GC2; FILM3, GC-NAB3, GC3; FILM4, GC-NAB4, GC4; FILM5, GC-NAB5, GC5, respectively. The factor loadings were extracted by making use of the factor analysis approach applied to each group. The orthogonal varimax rotation technique was used to obtain the rotated factor loadings corresponding to the first two factors. After the estimation of the relationship among and within groups, the results predict the existence of the NAB-FILM on the NAB modified glassy carbon electrodes.
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    A new approach to the characterization of the nano-surface structure by using factor analysis
    (Elsevier, 2012) Dinc, Erdal; Baleanu, Dumitru; Solak, Ali Osman; Eksi, Haslet; Guzel, Remziye
    The study provides a new approach to explore the existence of a nanostructure on the benzoic acid-modified glassy carbon electrode (BA-GC) system by applying factor analysis with varimax rotation of factors. The infrared spectra (IR) spectra of the bare glassy carbon electrodes (GC) and the BA-GC electrode systems with benzoic acid-nanofilm (BA-FILM) were obtained by using 10 different surface modification experiments. The IR data of the bare GC, BA-GC and BA-FILM were categorized into three series corresponding to the GC, BA-GC and BA-FILM. The factor analysis method was separately applied to each group to extract the factor loadings. By making use of these loadings, the rotated factor loadings corresponding to the first two factors were computed to estimate the relationship among and within groups. The results provided by the factor analysis method indicate the existence of the BA-FILM on the BA modified glassy carbon electrode. (C) 2011 Elsevier B.V. All rights reserved.
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    New Voltammetric Approach to the Quantitation of Paracetamol in Tablets and Syrup using Chemometric Optimization Technique
    (Pleiades Publishing Inc, 2019) Guzel, Remziye; Eksi, Haslet; Dinc, Erdal; Solak, Ali Osman
    A new voltammetric approach was developed for the determination of paracetamol in tablet and syrup samples using chemometric optimization. The method is based on the use of the gold nanoparticles-polyaniline (AuNPs-PA) modified pencil graphite electrode (PGE). Electrode system was fabricated by using the electrochemical reduction of gold on aniline modified pencil electrode to give gold nanoparticles. A 3(3) full factorial design was used to find optimal oxidation conditions of paracetamol on the AuNPs-PA-PGE. The optimal oxidation conditions of drug substance were found as -524 mV for the accumulation potential, 295 s for the accumulation time and pH 8.69 (for the phosphate buffer solution, 0.1 M). The determination of paracetamol was linear in the range of 2.0 x 10(-7)-6.0 x 10(-6) M with a detection limit of 5 x 10(-8) M. As a result, the proposed voltammetric approach gave satisfactory results for the determination of the related drug substance in tablets and syrup.
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    Spectroscopic and Electrochemical Characterization of Benzoylglycine-Modified Glassy Carbon Electrode: Electrocatalytic Effect Towards Dioxygen Reduction in Aqueous Media
    (Taylor & Francis Inc, 2011) Isbir-Turan, Aybuke A.; Ustundag, Zafer; Eksi, Haslet; Guzel, Remziye; Solak, Ali Osman
    Present work aims to create a benzoylglycine (BG)-modified glassy carbon (GC) substrate exploiting the electroreduction of diazonium salts. Dopamine was used to confirm the attachment of benzoylglycine molecules onto the glassy carbon surface by observing the blockage of the electron transfer using cyclic voltammetry (CV). BG-modified GC surface (BG-GC) was also characterized by Raman spectroscopy and electrochemical impedance spectroscopy (EIS) techniques. The ellipsometric thickness of the BG film was measured as approximately 14nm for seven CV cycles. The electrocatalytic effect of BG-GC electrode surface against dioxygen reduction was investigated. The catalytic effect for dioxygen reduction of the BG-GC surface was compared with that of 2-benzo[c]cinnoline, 2-benzo[c]cinnoline 6-oxide- and diethylene glycol bis(2-aminophenyl)ether-modified GC surfaces to clarify the mechanism of catalysis of the surfaces in terms of molecular structure.