The Experts below are selected from a list of 58692 Experts worldwide ranked by ideXlab platform
M. O. F. Goulart - One of the best experts on this subject based on the ideXlab platform.
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Amperometric sensor based on carbon nanotubes and electropolymerized vanillic acid for Simultaneous Determination of ascorbic acid, dopamine, and uric acid
Journal of Solid State Electrochemistry, 2016Co-Authors: L. V. Da Silva, F. A. S. Silva, L. T. Kubota, C. B. Lopes, P. R. Lima, E. O. Costa, W. Pinho Júnior, M. O. F. GoulartAbstract:This paper describes the development of a simple and efficient nanostructured platform based on multi-walled carbon nanotubes (MWCNT) functionalized with an in situ generated vanillic acid (VA) polymer. It was used as an analytical sensor for the Simultaneous Determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA). The electropolymerization process of VA, performed on MWCNT-modified glassy carbon electrode, produces three redox systems based on quinone/hydroquinone functionality, as observed by cyclic voltammetry. The amperometric sensor has as figures of merit for the Simultaneous Determination of AA, DA, and UA the following values: for AA, a linear range of 5–120 μM and detection limit of 3.5 μM; for DA, a linear range of 5–120 μM and detection limit of 4.5 μM; and for UA, a linear range of 5–120 μM and a detection limit of 1.5 μM. From the obtained performance, the development of the platform based on MWCNT/poly-VA is justified for the Simultaneous Determination of AA, DA, and UA.
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poly xanthurenic acid modified electrodes an amperometric sensor for the Simultaneous Determination of ascorbic and uric acids
Sensors and Actuators B-chemical, 2012Co-Authors: L. T. Kubota, C. B. Lopes, P. R. Lima, M. O. F. Goulart, Francisco De Assis Dos Santos SilvaAbstract:Abstract The poly-xanthurenic acid (poly-Xa)/multi-walled carbon nanotube (MWCNT)/glassy carbon modified electrode (poly-Xa/MWCNT/GCE) was successfully applied for the Simultaneous Determination of ascorbic (AA) and uric (UA) acids. Cyclic voltammetric results show that the modified electrode displays an excellent eletrocatalytic activity toward the oxidation of AA at a low potential (0.05 V versus Ag/AgCl) and anodic peak resolution (Δ E pa ), close to 300 mV versus Ag/AgCl, in solutions containing AA and UA. Values in the order of 10 6 L mol −1 s −1 were obtained for the kinetic constant k cat for the catalytic oxidation of AA, upon evaluation by cyclic voltammetry, chronoamperometry and RDE. Furthermore, the sensor provided limits of detection of 0.19 μmol L −1 and 0.31 μmol L −1 for AA and UA, respectively. The sensor was applied for the Simultaneous Determination of AA and UA in urine samples and the average recoveries for these samples were 99.9 (±2.5)% and 99.9 (±2.6)%, respectively.
Shenming Chen - One of the best experts on this subject based on the ideXlab platform.
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Simultaneous Determination for toxic ractopamine and salbutamol in pork sample using hybrid carbon nanotubes
Sensors and Actuators B-chemical, 2013Co-Authors: Kuochiang Lin, Chuenpon Hong, Shenming ChenAbstract:Abstract Hybrid carbon nanotubes (CNTs) and Nafion (NF) composites have been successfully prepared on an electrode surface with background current ratio as 3:4:16 for single-walled CNTs (SWCNT), multi-walled CNTs (MWCNT), and hybrid single-walled and multi-walled CNTs (SMWCNT), respectively. The SMWCNT shows good electrocatalytic properties to ractopamine and salbutamol, and the 1:1 is the optimized SWCNT:MWCNT ratio for SMWCNT preparation. This synergistic effect might be caused by more compact structure between SWCNT and MWCNT resulting in higher electroactive CNTs concentration on the electrode surface. When the results of using differential pulse voltammetry (DPV) with that of UV–visible spectroscopy are compared, DPV is more suitable for Simultaneous Determination of target species. High sensitivity of 86,917 μA mM −1 cm −2 and 65,842 μA mM −1 cm −2 ; low detection limit of 0.05 μM and 0.1 μM (S/N = 3); was estimated by amperometry for ractopamine and salbutamol, respectively. Simultaneous Determination of ractopamine and salbutamol was taken in pork samples with the average recoveries of 98.7% and 97.1%, respectively. It is stable without significant change at room temperature for the observation more than 30 days.
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electrochemically synthesized pt mno2 composite particles for Simultaneous Determination of catechol and hydroquinone
Sensors and Actuators B-chemical, 2012Co-Authors: Binesh Unnikrishnan, Shenming ChenAbstract:Abstract In this work we report the Simultaneous Determination of catechol (CC) and hydroquinone (HQ) at electrodeposited Pt–MnO2 particles on glassy carbon electrode. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) results revealed that spherical Pt and MnO2 particles deposited on GCE. Electrochemical impedance spectroscopy (EIS) studies showed that Pt nanoparticles in the Pt–MnO2 composite film help the facile transfer of electrons from MnO2 to the GCE; thereby it decreases the electron transfer resistance (Ret) of the film. The application of the Pt–MnO2 film for the electrocatalysis of CC and HQ was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Well defined voltammetric peaks were obtained for a mixture of equal concentrations of HQ and CC in pH 7 with a peak potential separation of 0.12 V. The Simultaneous Determination of CC and HQ was done by DPV. The linear range of detection of CC is 15 μM to 0.447 mM and HQ is 3 μM to 0.481 mM. Simultaneous Determination of HQ and CC in tap water samples has been studied. The film also detects HQ present in skin whitening cream. This report suggests that Pt–MnO2 composite is a promising material for electrocatalytic and electroanalytical applications.
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easy modification of glassy carbon electrode for Simultaneous Determination of ascorbic acid dopamine and uric acid
Biosensors and Bioelectronics, 2009Co-Authors: Soundappan Thiagarajan, Tsunghsuan Tsai, Shenming ChenAbstract:Abstract A glassy carbon electrode (GCE) has been modified by electrochemical oxidation in mild acidic media (0.1 mol l−1 H2SO4) and could be applied for individual and Simultaneous Determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Oxidized GCE shows a single redox couple (E0′ = −2.5 mV) which is based on the formation functional groups during the electrochemical pretreatment process. Proposed GCE successfully decreases the over potentials for the oxidation process of these species (AA, DA and UA) comparing with bare GCE. The oxidized GCE has its own simplicity, stability, high sensitivity and possesses the potential for Simultaneous Determination of AA, DA and UA.
Shuhua Cheng - One of the best experts on this subject based on the ideXlab platform.
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electrochemically pretreated screen printed carbon electrodes for the Simultaneous Determination of aminophenol isomers
Journal of Electroanalytical Chemistry, 2011Co-Authors: Shengming Wang, Shuhua ChengAbstract:Abstract This study reports that disposable, electrochemically pretreated screen-printed carbon electrodes (SPCE*) can be employed for the Simultaneous Determination of aminophenol isomers in aqueous buffer solution. In sharp contrast to untreated SPCE, voltammetric studies indicate that the oxidation peak potential of each analyte in an aminophenol isomer mixture may be separated at the activated SPCE*. The individual oxidation peak currents are greatly increased by first-order derivative techniques. All experimental parameters were optimized to improve responses. The derivative oxidation peak currents is proportional to the concentration of isomer over the range from 0.2 to 100 μM for 2-aminophenol (2AP), from 3.0 to 200 μM for 3-aminophenol (3AP), and from 0.2 to 200 μM for 4-aminophenol (4AP), with detection limits of 0.07, 0.16 and 0.05 μM, respectively. The proposed methods have excellent analytical characteristics that include ease of handling, high sensitivity, wide linear dynamic range and low detection limits. The assay was applied to the Simultaneous Determination of aminophenol isomers in river water with good recovery results.
Shengming Wang - One of the best experts on this subject based on the ideXlab platform.
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electrochemically pretreated screen printed carbon electrodes for the Simultaneous Determination of aminophenol isomers
Journal of Electroanalytical Chemistry, 2011Co-Authors: Shengming Wang, Shuhua ChengAbstract:Abstract This study reports that disposable, electrochemically pretreated screen-printed carbon electrodes (SPCE*) can be employed for the Simultaneous Determination of aminophenol isomers in aqueous buffer solution. In sharp contrast to untreated SPCE, voltammetric studies indicate that the oxidation peak potential of each analyte in an aminophenol isomer mixture may be separated at the activated SPCE*. The individual oxidation peak currents are greatly increased by first-order derivative techniques. All experimental parameters were optimized to improve responses. The derivative oxidation peak currents is proportional to the concentration of isomer over the range from 0.2 to 100 μM for 2-aminophenol (2AP), from 3.0 to 200 μM for 3-aminophenol (3AP), and from 0.2 to 200 μM for 4-aminophenol (4AP), with detection limits of 0.07, 0.16 and 0.05 μM, respectively. The proposed methods have excellent analytical characteristics that include ease of handling, high sensitivity, wide linear dynamic range and low detection limits. The assay was applied to the Simultaneous Determination of aminophenol isomers in river water with good recovery results.
P. R. Lima - One of the best experts on this subject based on the ideXlab platform.
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Amperometric sensor based on carbon nanotubes and electropolymerized vanillic acid for Simultaneous Determination of ascorbic acid, dopamine, and uric acid
Journal of Solid State Electrochemistry, 2016Co-Authors: L. V. Da Silva, F. A. S. Silva, L. T. Kubota, C. B. Lopes, P. R. Lima, E. O. Costa, W. Pinho Júnior, M. O. F. GoulartAbstract:This paper describes the development of a simple and efficient nanostructured platform based on multi-walled carbon nanotubes (MWCNT) functionalized with an in situ generated vanillic acid (VA) polymer. It was used as an analytical sensor for the Simultaneous Determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA). The electropolymerization process of VA, performed on MWCNT-modified glassy carbon electrode, produces three redox systems based on quinone/hydroquinone functionality, as observed by cyclic voltammetry. The amperometric sensor has as figures of merit for the Simultaneous Determination of AA, DA, and UA the following values: for AA, a linear range of 5–120 μM and detection limit of 3.5 μM; for DA, a linear range of 5–120 μM and detection limit of 4.5 μM; and for UA, a linear range of 5–120 μM and a detection limit of 1.5 μM. From the obtained performance, the development of the platform based on MWCNT/poly-VA is justified for the Simultaneous Determination of AA, DA, and UA.
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poly xanthurenic acid modified electrodes an amperometric sensor for the Simultaneous Determination of ascorbic and uric acids
Sensors and Actuators B-chemical, 2012Co-Authors: L. T. Kubota, C. B. Lopes, P. R. Lima, M. O. F. Goulart, Francisco De Assis Dos Santos SilvaAbstract:Abstract The poly-xanthurenic acid (poly-Xa)/multi-walled carbon nanotube (MWCNT)/glassy carbon modified electrode (poly-Xa/MWCNT/GCE) was successfully applied for the Simultaneous Determination of ascorbic (AA) and uric (UA) acids. Cyclic voltammetric results show that the modified electrode displays an excellent eletrocatalytic activity toward the oxidation of AA at a low potential (0.05 V versus Ag/AgCl) and anodic peak resolution (Δ E pa ), close to 300 mV versus Ag/AgCl, in solutions containing AA and UA. Values in the order of 10 6 L mol −1 s −1 were obtained for the kinetic constant k cat for the catalytic oxidation of AA, upon evaluation by cyclic voltammetry, chronoamperometry and RDE. Furthermore, the sensor provided limits of detection of 0.19 μmol L −1 and 0.31 μmol L −1 for AA and UA, respectively. The sensor was applied for the Simultaneous Determination of AA and UA in urine samples and the average recoveries for these samples were 99.9 (±2.5)% and 99.9 (±2.6)%, respectively.
