The Experts below are selected from a list of 33213 Experts worldwide ranked by ideXlab platform
Mehmet Gumustas - One of the best experts on this subject based on the ideXlab platform.
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electroanalytical characteristics of antipsychotic drug ziprasidone and its determination in pharmaceuticals and serum samples on Solid Electrodes
Talanta, 2010Co-Authors: Dilek Kul, Mehmet Gumustas, Bengi Uslu, Sibel A OzkanAbstract:Ziprasidone is a psychotropic agent used for the treatment of schizophrenia. Its oxidation was investigated electrochemically at boron-doped diamond and glassy carbon Electrodes using cyclic, differential pulse, and square wave voltammetry. The dependence of the peak current and peak potentials on pH, concentration, nature of the buffer, and scan rate were examined. The process was diffusion and adsorption controlled for boron-doped diamond and glassy carbon Electrodes, respectively. The possible mechanism of oxidation was discussed with some model compounds that have indole and piperazine oxidations. A linear response was obtained between 8 x 10(-7) and 8 x 10(-5) M for the first peak in acetate buffer (pH 5.5) and between 2 x 10(-6) and 2 x 10(-4) M for the second peak in 0.1 M H(2)SO(4) with boron-doped diamond electrode for differential pulse and square wave voltammetric techniques. The reproducibility and accuracy of the proposed methods were found between 0.31 and 1.20, 99.27 and 100.22, respectively. The recovery studies were also achieved to check selectivity and accuracy of the methods. The proposed methods were applied for the determination of ziprasidone from pharmaceutical dosage forms and human serum samples without any time-consuming extraction, separation, evaporation or adsorption steps prior to drug assay except precipitation of the proteins using acetonitrile. The results were statistically compared with those obtained through an established LC-UV technique, no significant differences were been found between the voltammetric and LC methods.
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electrochemical evaluation and determination of antiretroviral drug fosamprenavir using boron doped diamond and glassy carbon Electrodes
Analytical and Bioanalytical Chemistry, 2010Co-Authors: Mehmet Gumustas, Sibel A OzkanAbstract:Fosamprenavir is a pro-drug of the antiretroviral protease inhibitor amprenavir and is oxidizable at Solid Electrodes. The anodic oxidation behavior of fosamprenavir was investigated using cyclic and linear sweep voltammetry at boron-doped diamond and glassy carbon Electrodes. In cyclic voltammetry, depending on pH values, fosamprenavir showed one sharp irreversible oxidation peak or wave depending on the working electrode. The mechanism of the oxidation process was discussed. The voltammetric study of some model compounds allowed elucidation of the possible oxidation mechanism of fosamprenavir. The aim of this study was to determine fosamprenavir levels in pharmaceutical formulations and biological samples by means of electrochemical methods. Using the sharp oxidation response, two voltammetric methods were described for the determination of fosamprenavir by differential pulse and square-wave voltammetry at the boron-doped diamond and glassy carbon Electrodes. These two voltammetric techniques are 0.1 M H2SO4 and phosphate buffer at pH 2.0 which allow quantitation over a 4 × 10−6 to 8 × 10−5 M range using boron-doped diamond and a 1 × 10−5 to 1 × 10−4 M range using glassy carbon Electrodes, respectively, in supporting electrolyte. All necessary validation parameters were investigated and calculated. These methods were successfully applied for the analysis of fosamprenavir pharmaceutical dosage forms, human serum and urine samples. The standard addition method was used in biological media using boron-doped diamond electrode. No electroactive interferences from the tablet excipients or endogenous substances from biological material were found. The results were statistically compared with those obtained through an established HPLC-UV technique; no significant differences were found between the voltammetric and HPLC methods.
Sibel A Ozkan - One of the best experts on this subject based on the ideXlab platform.
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electroanalysis in biomedical and pharmaceutical sciences voltammetry amperometry biosensors applications
2015Co-Authors: Sibel A Ozkan, Petr Zuman, Jeanmichel Kauffmann, Ana Maria Oliveira BrettAbstract:Introduction.- Polarography in Studies of Pharmaceuticals.- Electroanalytical Techniques Most Frequently Used in Drug Analysis.- Solid Electrodes in Drug Analysis.- Screen Printed Electrodes (SPE) for Drug Compounds Determination.- Electrochemical Biosensors for Drug Analysis.- Electrochemical and hyphenated electrochemical detectors in liquid chromatography and flow injection systems for drug compound analysis.- Electroanalytical Methods Validation in Pharmaceutical Analysis and Their Applications.- Applications for Drug Assays.
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electroanalytical characteristics of antipsychotic drug ziprasidone and its determination in pharmaceuticals and serum samples on Solid Electrodes
Talanta, 2010Co-Authors: Dilek Kul, Mehmet Gumustas, Bengi Uslu, Sibel A OzkanAbstract:Ziprasidone is a psychotropic agent used for the treatment of schizophrenia. Its oxidation was investigated electrochemically at boron-doped diamond and glassy carbon Electrodes using cyclic, differential pulse, and square wave voltammetry. The dependence of the peak current and peak potentials on pH, concentration, nature of the buffer, and scan rate were examined. The process was diffusion and adsorption controlled for boron-doped diamond and glassy carbon Electrodes, respectively. The possible mechanism of oxidation was discussed with some model compounds that have indole and piperazine oxidations. A linear response was obtained between 8 x 10(-7) and 8 x 10(-5) M for the first peak in acetate buffer (pH 5.5) and between 2 x 10(-6) and 2 x 10(-4) M for the second peak in 0.1 M H(2)SO(4) with boron-doped diamond electrode for differential pulse and square wave voltammetric techniques. The reproducibility and accuracy of the proposed methods were found between 0.31 and 1.20, 99.27 and 100.22, respectively. The recovery studies were also achieved to check selectivity and accuracy of the methods. The proposed methods were applied for the determination of ziprasidone from pharmaceutical dosage forms and human serum samples without any time-consuming extraction, separation, evaporation or adsorption steps prior to drug assay except precipitation of the proteins using acetonitrile. The results were statistically compared with those obtained through an established LC-UV technique, no significant differences were been found between the voltammetric and LC methods.
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electrochemical evaluation and determination of antiretroviral drug fosamprenavir using boron doped diamond and glassy carbon Electrodes
Analytical and Bioanalytical Chemistry, 2010Co-Authors: Mehmet Gumustas, Sibel A OzkanAbstract:Fosamprenavir is a pro-drug of the antiretroviral protease inhibitor amprenavir and is oxidizable at Solid Electrodes. The anodic oxidation behavior of fosamprenavir was investigated using cyclic and linear sweep voltammetry at boron-doped diamond and glassy carbon Electrodes. In cyclic voltammetry, depending on pH values, fosamprenavir showed one sharp irreversible oxidation peak or wave depending on the working electrode. The mechanism of the oxidation process was discussed. The voltammetric study of some model compounds allowed elucidation of the possible oxidation mechanism of fosamprenavir. The aim of this study was to determine fosamprenavir levels in pharmaceutical formulations and biological samples by means of electrochemical methods. Using the sharp oxidation response, two voltammetric methods were described for the determination of fosamprenavir by differential pulse and square-wave voltammetry at the boron-doped diamond and glassy carbon Electrodes. These two voltammetric techniques are 0.1 M H2SO4 and phosphate buffer at pH 2.0 which allow quantitation over a 4 × 10−6 to 8 × 10−5 M range using boron-doped diamond and a 1 × 10−5 to 1 × 10−4 M range using glassy carbon Electrodes, respectively, in supporting electrolyte. All necessary validation parameters were investigated and calculated. These methods were successfully applied for the analysis of fosamprenavir pharmaceutical dosage forms, human serum and urine samples. The standard addition method was used in biological media using boron-doped diamond electrode. No electroactive interferences from the tablet excipients or endogenous substances from biological material were found. The results were statistically compared with those obtained through an established HPLC-UV technique; no significant differences were found between the voltammetric and HPLC methods.
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Solid Electrodes in electroanalytical chemistry: present applications and prospects for high throughput screening of drug compounds.
Combinatorial chemistry & high throughput screening, 2007Co-Authors: Bengi Uslu, Sibel A OzkanAbstract:This review summarizes recent progress in the development and application of Solid Electrodes to the screening of pharmaceutical dosage forms and biological fluids. Recent trends and advances in the electroanalytical chemistry of Solid Electrodes, microElectrodes and electrochemical sensors are reviewed. The varieties of Solid Electrodes and their basic physico-chemical properties and some specific characteristics including some supramolecular phenomena at their surface are surveyed. This review also includes some selected designs and their applications. Despite many reviews about individual Solid Electrodes in the literature, this review offers the first comprehensive report on all forms of Solid Electrodes. Special attention is paid to the possibilities of Solid Electrodes in high throughput electroanalytical investigation of drug dosage forms and biological samples using modern electroanalytical techniques. Various selected studies on these subjects since 1996 are reviewed in this paper.
Kenneth H Nealson - One of the best experts on this subject based on the ideXlab platform.
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extracellular electron transfer of shewanella oneidensis mr 1 for cathodic hydrogen evolution reaction
Electrochimica Acta, 2019Co-Authors: Yongjia Zhang, Dawei Liang, Yan Xiang, Beizhen Xie, Hong Liu, Kenneth H NealsonAbstract:Abstract Electron transfer from Solid Electrodes to microbes through reversed extracellular electron transfer (EET) has been realized in bioelectrochemical systems (BESs), which have gained much attention in the realm of bioenergy and bioremediation. In this study, Shewanella oneidensis MR-1 was found to catalyze cathodic hydrogen evolution (HEv) at a potential of −0.758 V vs. standard hydrogen electrode (SHE) in a BES. Analysis via differential pulse voltammetry analysis revealed a strong enhancement of HEv by added nicotinamide adenine dinucleotide (NAD) but no impact by the addition of either NADH or riboflavin (RF) and flavin mononucleotide (FMN). Moreover, NADH, when added in combination with flavins inhibited cathodic EET and HEv. The mechanism by which these stimulations and inhibitions are not clear at this time. In summary, this study lays the foundation for understanding both reversed EET and hydrogen evolution catalyzed by S. oneidensis MR-1.
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quantification of electron transfer rates to a Solid phase electron acceptor through the stages of biofilm formation from single cells to multicellular communities
Environmental Science & Technology, 2010Co-Authors: Jeffrey S Mclean, Greg Wanger, Yuri A Gorby, Martin E Wainstein, Jeffrey B Mcquaid, Shunichi Ishii, Orianna Bretschger, Haluk Beyenal, Kenneth H NealsonAbstract:Microbial fuel cell (MFC) technology has enabled new insights into the mechanisms of electron transfer from dissimilatory metal reducing bacteria to a Solid phase electron acceptor. Using Solid Electrodes as electron acceptors enables quantitative real-time measurements of electron transfer rates to these surfaces. We describe here an optically accessible, dual anode, continuous flow MFC that enables real-time microscopic imaging of anode populations as they develop from single attached cells to a mature biofilms. We used this system to characterize how differences in external resistance affect cellular electron transfer rates on a per cell basis and overall biofilm development in Shewanella oneidensis strain MR-1. When a low external resistance (100 Ω) was used, estimates of current per cell reached a maximum of 204 fA/cell (1.3 × 106 e− cell−1 sec−1), while when a higher (1 MΩ) resistance was used, only 75 fA/cell (0.4 × 106 e− cell−1 sec−1) was produced. The 1 MΩ anode biomass consistently developed in...
Guanglei Cui - One of the best experts on this subject based on the ideXlab platform.
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integrated interface strategy toward room temperature Solid state lithium batteries
ACS Applied Materials & Interfaces, 2018Co-Authors: Yantao Wang, Bingbing Chen, Shanmu Dong, Jingchao Chai, Longfei Cui, Guanglei CuiAbstract:Solid-state lithium batteries have drawn wide attention to address the safety issues of power batteries. However, the development of Solid-state lithium batteries is substantially limited by the poor electrochemical performances originating from the rigid interface between Solid Electrodes and Solid-state electrolytes. In this work, a composite of poly(vinyl carbonate) and Li10SnP2S12 Solid-state electrolyte is fabricated successfully via in situ polymerization to improve the rigid interface issues. The composite electrolyte presents a considerable room temperature conductivity of 0.2 mS cm–1, an electrochemical window exceeding 4.5 V, and a Li+ transport number of 0.6. It is demonstrated that Solid-state lithium metal battery of LiFe0.2Mn0.8PO4 (LFMP)/composite electrolyte/Li can deliver a high capacity of 130 mA h g–1 with considerable capacity retention of 88% and Coulombic efficiency of exceeding 99% after 140 cycles at the rate of 0.5 C at room temperature. The superior electrochemical performance ca...
O A Petrii - One of the best experts on this subject based on the ideXlab platform.
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real surface area measurements in electrochemistry
Journal of Electroanalytical Chemistry, 1992Co-Authors: S Trasatti, O A PetriiAbstract:Abstract Electrode reaction rates and most double layer parameters are extensive quantities and have to be referred to the unit area of the interface. Knowledge of the real surface area of Electrodes is therefore needed. Comparison of experimental data with theories or of experimental results for different materials and/or from different laboratories to each other is physically groundless without normalization to unit real area of the electrode surface. Different methods have been proposed to normalize experimental data specifically with Solid Electrodes. Some of them are not sufficiently justified from a physical point of view. A few of them are definitely questionable. The purpose of this document is to scrutinize the basis on which the various methods and approaches rest, in order to assess their relevance to the specific electrochemical situation and, as far as possible, their absolute reliability. Methods and approaches are applicable to (a) liquid Electrodes, (b) polycrystalline and single crystal face Solids, (c) supported, compressed and disperse powders. The applicability of the various techniques to each specific case is to be verified. After an introductory discussion of the “concept” of real surface area, fifteen methods, eleven applied in situ and four ex situ, are scrutinized. For each of them, after a description of the principles on which it is based, limitations are discussed and recommendations are given.