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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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    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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    ICP-OES Method for the Determination of Fe, Co, Mn, Cu, Pb, and Zn in Ore Samples From the Keban Region Using Experimental Design and Optimization Methodology
    (Atomic Spectroscopy Press Ltd, 2016) Orala, Elif Varhan; Ziyadanogullari, Berrin; Aydin, Firat; Dinc, Erdal; Ziyadanogullari, Recep
    A new approach based on the use of inductively coupled plasma optical emission spectrometry (ICP-OES) is presented for the quantitative determination of Fe, Co, Mn, Cu, Pb, and Zn in ore samples obtained from the Keban Region, Turkey. A 33 full factorial design with 27 sample runs was used to find the optimal sequential extraction conditions for the analysis of these samples. Under optimized conditions for each step of the sequential extraction procedure, calibration curves for the respective metals were obtained by measuring the absorbance values at 238.2 nm for Fe, 228.6 nm for Co, 257.6 nm for Mn, 327.4 nm for Cu, 220.4 nm for Pb, and 206.2 nm for Zn. The proposed ICP-OES method was successfully applied to the quantitative analysis of real ore samples containing Fe, Co, Mn, Cu, Pb, and Zn. Good agreement was found for the analytical results of these metals.
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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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    A New UPLC Approach for the Simultaneous Quantitative Estimation of Four Compounds in a Cough Syrup Formulation
    (Oxford Univ Press Inc, 2016) Turak, Fatma; Guzel, Remziye; Dinc, Erdal
    A new ultra-performance liquid chromatographic (UPLC) method was developed for the simultaneous estimation of potassium guaiacolsulfonate (PGS), guaifenesin (GUA), diphenhydramine HCl (DIP) and carbepentane citrate (CAR) in a commercial cough syrup. The chromatographic separation of four compounds PGS, GUA, DIP and CAR was performed on a BEH phenyl column (100 x 2.1 mm, 1.7 mu m i.d.) using a mobile phase consisting of acetonitrile and 0.1 MHCl (50 : 50, v/v). In addition, the optimized conditions of the chromatographic analysis were found with the flow rate of 0.38 mL/min, the column temperature of 30 degrees C and the injection volume of 1.2 mu L with the photodiode array detection of 220 nm. Calibration curves in the concentration ranges of 10-98 mu g/mL for PGS, 5-80 mu g/mL for GUA, 5-25 mu g/mL for DIP and CAR were computed by the regression of the analyte concentration on the chromatographic peak area. The newly developed UPLC method was validated by analyzing the quaternary mixtures of the related compounds, intraday and interday experiment and standard addition samples. After method validation, the proposed UPLC approach was successfully applied for the analysis of the commercial syrup formulation containing PGS, GUA, DIP and CAR compounds.
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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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    Simultaneous determination of ascorbic acid and caffeine in commercial soft drinks using reversed-phase ultraperformance liquid chromatography
    (Food & Drug Adminstration, 2017) Turak, Fatma; Guzel, Remziye; Dinc, Erdal
    A new reversed-phase ultraperformance liquid chromatography method with a photodiode array detector was developed for the quantification of ascorbic acid (AA) and caffeine (CAF) in 11 different commercial drinks consisting of one energy drink and 10 ice tea drinks. Separation of the analyzed AA and CAF with an internal standard, caffeic acid, was performed on a Waters BEH C-18 column (100 mm x 2.1 mm, 1.7 mu m i.d.), using a mobile phase consisting of acetonitrile and 0.2M H3PO4 (11: 89, v/v) with a flow rate of 0.25 mL/min and an injection volume of 1.0 mu L. Calibration graphs for AA and CAF were computed from the peak area ratio of AA/internal standard and CAF/internal standard detected at 244.0 nm and 273.6 nm, respectively. The developed reversed-phase ultraperformance liquid chromatography method was validated by analyzing standard addition samples. The proposed reversed-phase ultraperformance liquid chromatography method gave us successful results for the quantitative analysis of commercial drinks containing AA and CAF substances. Copyright (C) 2016, Food and Drug Administration, Taiwan. Published by Elsevier Taiwan LLC.