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Sanghamitra Chatterjee - One of the best experts on this subject based on the ideXlab platform.
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voltammetric biosensors for the determination of paracetamol at carbon nanotube modified pyrolytic Graphite Electrode
Sensors and Actuators B-chemical, 2010Co-Authors: Rajendra N. Goyal, Vinod Kumar Gupta, Sanghamitra ChatterjeeAbstract:Abstract The voltammetric oxidation of paracetamol on single-walled carbon nanotubes (SWNT) modified edge plane pyrolytic Graphite Electrode (EPPGE) was explored in phosphate buffer solution by using square wave voltammetry. Cyclic and square wave voltammetry studies indicated the oxidation of paracetamol at the Electrode surface through a two-electron reversible step and fundamentally controlled by adsorption. Besides semi-infinite planar diffusion, the role of thin layer diffusion at nanotube modified Electrodes is also suggested. The sensitivity at SWNT modified EPPGE is ∼2 times more than that at MWNT modified EPPGE. Paracetamol gave a sensitive oxidation peak at ∼187 mV at pH 7.2 (μ = 0.5 M) which was used to quantitate the drug in the range of 5–1000 nM with a detection limit of 2.9 × 10−9 M at SWNT modified EPPGE. The interfering effect of physiologically common interferents on the current response of paracetamol has been reported. The procedure was successfully applied for the assay of paracetamol in pharmaceutical formulations. The applicability of the developed method to determine the drug in human urine samples obtained after 4 h of administration of paracetamol is illustrated.
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simultaneous determination of adenosine and inosine using single wall carbon nanotubes modified pyrolytic Graphite Electrode
Talanta, 2008Co-Authors: Rajendra N. Goyal, Vinod Kumar Gupta, Sanghamitra ChatterjeeAbstract:Abstract Voltammetric determination of adenosine and inosine has been carried out at single-wall carbon nanotubes (SWNTs) modified pyrolytic Graphite Electrode (PGE) at pH 7.2 using Osteryoung square wave voltammetry (OSWV). The modified Electrode exhibits remarkable electrocatalytic properties towards adenosine and inosine oxidation with a peak potential of ∼1229 mV and 1348 mV, respectively. Linear calibration curves are obtained over the concentration range 0.5 μM to 1.0 mM in adenosine and 10 μM to 1.0 mM in inosine with sensitivity of 1.0 μA μM−1 and 1.9 μA μM−1 for adenosine and inosine respectively. The limit of detection for adenosine and inosine was found to be 0.51 × 10−7 M and 2.04 × 10−7 M, respectively. The proposed method was also used to estimate these compounds in human blood plasma and urine samples and the method was validated using HPLC.
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electrochemical oxidation of 2 3 dideoxyadenosine at pyrolytic Graphite Electrode
Electrochimica Acta, 2008Co-Authors: Rajendra N. Goyal, Vinod Kumar Gupta, Sanghamitra ChatterjeeAbstract:Abstract The oxidation chemistry of 2′,3′-dideoxyadenosine (I) has been studied at a pyrolytic Graphite Electrode (PGE) in the pH range 2.4–10.9 and a well defined oxidation peak was noticed. The peak potential of the peak was linearly dependent on pH with dEp/dpH as 42 mV/pH. Voltammetric, coulometric, spectral studies and product analysis indicate that the oxidation of (I) occurs in an EC reaction involving 6e−, 6H+ process at pH 7.2 to give allantoin, C–C dimer and dideoxyribose as the major products and a C–O–O–C linked dimer as a minor product. Tentative mechanisms for the formation of the products have also been suggested. A comparison of peak potential value of 2′,3′-dideoxyadenosine with adenosine and 2′-deoxyadensoine indicated that the difference is insignificant which has further been supported by the calculations of difference of energies of lowest unoccupied and highest occupied molecular orbitals.
Vinod Kumar Gupta - One of the best experts on this subject based on the ideXlab platform.
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voltammetric biosensors for the determination of paracetamol at carbon nanotube modified pyrolytic Graphite Electrode
Sensors and Actuators B-chemical, 2010Co-Authors: Rajendra N. Goyal, Vinod Kumar Gupta, Sanghamitra ChatterjeeAbstract:Abstract The voltammetric oxidation of paracetamol on single-walled carbon nanotubes (SWNT) modified edge plane pyrolytic Graphite Electrode (EPPGE) was explored in phosphate buffer solution by using square wave voltammetry. Cyclic and square wave voltammetry studies indicated the oxidation of paracetamol at the Electrode surface through a two-electron reversible step and fundamentally controlled by adsorption. Besides semi-infinite planar diffusion, the role of thin layer diffusion at nanotube modified Electrodes is also suggested. The sensitivity at SWNT modified EPPGE is ∼2 times more than that at MWNT modified EPPGE. Paracetamol gave a sensitive oxidation peak at ∼187 mV at pH 7.2 (μ = 0.5 M) which was used to quantitate the drug in the range of 5–1000 nM with a detection limit of 2.9 × 10−9 M at SWNT modified EPPGE. The interfering effect of physiologically common interferents on the current response of paracetamol has been reported. The procedure was successfully applied for the assay of paracetamol in pharmaceutical formulations. The applicability of the developed method to determine the drug in human urine samples obtained after 4 h of administration of paracetamol is illustrated.
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simultaneous determination of adenosine and inosine using single wall carbon nanotubes modified pyrolytic Graphite Electrode
Talanta, 2008Co-Authors: Rajendra N. Goyal, Vinod Kumar Gupta, Sanghamitra ChatterjeeAbstract:Abstract Voltammetric determination of adenosine and inosine has been carried out at single-wall carbon nanotubes (SWNTs) modified pyrolytic Graphite Electrode (PGE) at pH 7.2 using Osteryoung square wave voltammetry (OSWV). The modified Electrode exhibits remarkable electrocatalytic properties towards adenosine and inosine oxidation with a peak potential of ∼1229 mV and 1348 mV, respectively. Linear calibration curves are obtained over the concentration range 0.5 μM to 1.0 mM in adenosine and 10 μM to 1.0 mM in inosine with sensitivity of 1.0 μA μM−1 and 1.9 μA μM−1 for adenosine and inosine respectively. The limit of detection for adenosine and inosine was found to be 0.51 × 10−7 M and 2.04 × 10−7 M, respectively. The proposed method was also used to estimate these compounds in human blood plasma and urine samples and the method was validated using HPLC.
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electrochemical oxidation of 2 3 dideoxyadenosine at pyrolytic Graphite Electrode
Electrochimica Acta, 2008Co-Authors: Rajendra N. Goyal, Vinod Kumar Gupta, Sanghamitra ChatterjeeAbstract:Abstract The oxidation chemistry of 2′,3′-dideoxyadenosine (I) has been studied at a pyrolytic Graphite Electrode (PGE) in the pH range 2.4–10.9 and a well defined oxidation peak was noticed. The peak potential of the peak was linearly dependent on pH with dEp/dpH as 42 mV/pH. Voltammetric, coulometric, spectral studies and product analysis indicate that the oxidation of (I) occurs in an EC reaction involving 6e−, 6H+ process at pH 7.2 to give allantoin, C–C dimer and dideoxyribose as the major products and a C–O–O–C linked dimer as a minor product. Tentative mechanisms for the formation of the products have also been suggested. A comparison of peak potential value of 2′,3′-dideoxyadenosine with adenosine and 2′-deoxyadensoine indicated that the difference is insignificant which has further been supported by the calculations of difference of energies of lowest unoccupied and highest occupied molecular orbitals.
Rajendra N. Goyal - One of the best experts on this subject based on the ideXlab platform.
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voltammetric biosensors for the determination of paracetamol at carbon nanotube modified pyrolytic Graphite Electrode
Sensors and Actuators B-chemical, 2010Co-Authors: Rajendra N. Goyal, Vinod Kumar Gupta, Sanghamitra ChatterjeeAbstract:Abstract The voltammetric oxidation of paracetamol on single-walled carbon nanotubes (SWNT) modified edge plane pyrolytic Graphite Electrode (EPPGE) was explored in phosphate buffer solution by using square wave voltammetry. Cyclic and square wave voltammetry studies indicated the oxidation of paracetamol at the Electrode surface through a two-electron reversible step and fundamentally controlled by adsorption. Besides semi-infinite planar diffusion, the role of thin layer diffusion at nanotube modified Electrodes is also suggested. The sensitivity at SWNT modified EPPGE is ∼2 times more than that at MWNT modified EPPGE. Paracetamol gave a sensitive oxidation peak at ∼187 mV at pH 7.2 (μ = 0.5 M) which was used to quantitate the drug in the range of 5–1000 nM with a detection limit of 2.9 × 10−9 M at SWNT modified EPPGE. The interfering effect of physiologically common interferents on the current response of paracetamol has been reported. The procedure was successfully applied for the assay of paracetamol in pharmaceutical formulations. The applicability of the developed method to determine the drug in human urine samples obtained after 4 h of administration of paracetamol is illustrated.
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simultaneous determination of adenosine and inosine using single wall carbon nanotubes modified pyrolytic Graphite Electrode
Talanta, 2008Co-Authors: Rajendra N. Goyal, Vinod Kumar Gupta, Sanghamitra ChatterjeeAbstract:Abstract Voltammetric determination of adenosine and inosine has been carried out at single-wall carbon nanotubes (SWNTs) modified pyrolytic Graphite Electrode (PGE) at pH 7.2 using Osteryoung square wave voltammetry (OSWV). The modified Electrode exhibits remarkable electrocatalytic properties towards adenosine and inosine oxidation with a peak potential of ∼1229 mV and 1348 mV, respectively. Linear calibration curves are obtained over the concentration range 0.5 μM to 1.0 mM in adenosine and 10 μM to 1.0 mM in inosine with sensitivity of 1.0 μA μM−1 and 1.9 μA μM−1 for adenosine and inosine respectively. The limit of detection for adenosine and inosine was found to be 0.51 × 10−7 M and 2.04 × 10−7 M, respectively. The proposed method was also used to estimate these compounds in human blood plasma and urine samples and the method was validated using HPLC.
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electrochemical oxidation of 2 3 dideoxyadenosine at pyrolytic Graphite Electrode
Electrochimica Acta, 2008Co-Authors: Rajendra N. Goyal, Vinod Kumar Gupta, Sanghamitra ChatterjeeAbstract:Abstract The oxidation chemistry of 2′,3′-dideoxyadenosine (I) has been studied at a pyrolytic Graphite Electrode (PGE) in the pH range 2.4–10.9 and a well defined oxidation peak was noticed. The peak potential of the peak was linearly dependent on pH with dEp/dpH as 42 mV/pH. Voltammetric, coulometric, spectral studies and product analysis indicate that the oxidation of (I) occurs in an EC reaction involving 6e−, 6H+ process at pH 7.2 to give allantoin, C–C dimer and dideoxyribose as the major products and a C–O–O–C linked dimer as a minor product. Tentative mechanisms for the formation of the products have also been suggested. A comparison of peak potential value of 2′,3′-dideoxyadenosine with adenosine and 2′-deoxyadensoine indicated that the difference is insignificant which has further been supported by the calculations of difference of energies of lowest unoccupied and highest occupied molecular orbitals.
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Oxidation chemistry of 2′-deoxyadenosine at pyrolytic Graphite Electrode
Bioelectrochemistry, 2006Co-Authors: Rajendra N. Goyal, Aikta DhawanAbstract:Abstract The electrochemical oxidation of 2′-deoxyadenosine has been investigated in phosphate containing supporting electrolytes in pH range 2–10 at a pyrolytic Graphite Electrode by cyclic sweep voltammetry, spectral studies, controlled potential electrolysis and related techniques. The oxidation of 2′-deoxyadenosine occurred in a single well-defined oxidation peak (I a ), over the entire pH range. The electrooxidation occurred by the loss of 6.0 ± 0.5 e − per mole over the entire pH range. The kinetics of the decay of the UV-absorbing intermediates has been studied and found to follow pseudo first order kinetics having rate constant ( k ) in the range (5.7–7.7) × 10 − 4 s − 1 . The major products of electrooxidation were separated by HPLC and characterized by GC–MS/MS, 1 H NMR and a tentative mechanism for electrooxidation of 2′-deoxyadenosine has been suggested.
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Oxidation of 2-aminoquinoline at a stationary pyrolytic Graphite Electrode
Analytica Chimica Acta, 2002Co-Authors: N.c. Mathur, Rajendra N. Goyal, W.u. MalikAbstract:Abstract The oxidation of 2-aminoquinoline was studied at a stationary pyrolytic Graphite Electrode in methanol-phosphate buffer at 25°C using various electroanalytical techniques. In the entire pH range (2.2–10.4), 2-aminoquinoline is oxidized and exhibits a well defined oxidation peak following a 2e − , 2H + process to give, 2,2′-azoquinoline as the major product. The linear relationship between peak current at a pyrolytic Graphite Electrode and concentration indicated that 2-aminoquinoline can be determined in the concentration range 0.1–1.0 mM. On the basis of cyclic voltammetry, spectral studies and controlled-potential coulometry, a mechanism of the Electrode process is proposed.
Qian Xu - One of the best experts on this subject based on the ideXlab platform.
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an electrochemically activated Graphite Electrode with excellent kinetics for Electrode processes of v ii v iii and v iv v v couples in a vanadium redox flow battery
RSC Advances, 2014Co-Authors: Lingxu Yang, Qian XuAbstract:An electrochemically activated Graphite Electrode (EAGE) was obtained by a simple and moderate method of anodic potentiostatic polarization. The composition, microstructure, and electrochemical properties of the EAGE were characterized by high-resolution X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the electrochemical activity and the reversibility for Electrode processes of V(II)/V(III) and V(IV)/V(V) couples on the EAGE are significantly improved due to the introduced CO and COOH groups. The rate constant of charge transfer for the anodic oxidation of V(IV) on the EAGE was determined to be 8.17 × 10−4 cm s−1, which is about 20 times larger than the 4.09 × 10−5 cm s−1 rate constant on the pristine Graphite Electrode.
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On-line mass spectrometry study of electrochemical corrosion of the Graphite Electrode for vanadium redox flow battery
Electrochemistry Communications, 2013Co-Authors: Qian XuAbstract:The electrochemical corrosion of the Graphite Electrode for vanadium redox flow battery is investigated by on-line mass spectrometry analysis. The results show that CO2 and CO form and evolve more preferably than O-2 on the Graphite anode, which lead to the electrochemical corrosion of the Graphite Electrode. Furthermore, the evolution rate of O-2 is the highest one among evolved gases if the polarization potential becomes too positive. The oxidation of VO2+ on the Graphite Electrode in 2 M H2SO4 + 2 M VOSO4 hinders the carbon oxidation reaction and retards the electrochemical corrosion of the Graphite Electrode. (C) 2012 Elsevier B.V. All rights reserved.
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corrosion behavior of a positive Graphite Electrode in vanadium redox flow battery
Electrochimica Acta, 2011Co-Authors: Qian Xu, Yonglian QiaoAbstract:a b s t r a c t The Graphite plate is easily suffered from corosion because of CO2 evolution when it acts as the positive Electrode for vanadium redox flow battery. The aim is to obtain the initial potential for gas evolution on a positive Graphite Electrode in 2 mol dm −3 H2SO4 + 2 mol dm −3 VOSO4 solution. The effects of polarization potential, operating temperature and polarization time on extent of Graphite corrosion are investigated by potentiodynamic and potentiostatic techniques. The surface characteristics of Graphite Electrode before and after corrosion are examined by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. The results show that the gas begins to evolve on the Graphite Electrode when the anodic polarization potential is higher than 1.60 V vs saturated calomel Electrode at 20 ◦C. The CO2 evolution on the Graphite Electrode can lead to intergranular corrosion of the Graphite when the polarization potential reaches 1.75 V. In addition, the functional groups of COOH and C O introduced on the surface of Graphite Electrode during corrosion can catalyze the formation of CO2, therefore, accelerates
Hongyu Wang - One of the best experts on this subject based on the ideXlab platform.
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hexafluorophosphate intercalation into Graphite Electrode from gamma butyrolactone solutions in activated carbon Graphite capacitors
Journal of Power Sources, 2015Co-Authors: Shengfeng Tian, Masaki Yoshio, Li Qi, Hongyu WangAbstract:Abstract In our recent work, the solvent of ethylene carbonate (EC) has been found to retard the intercalation of anions into Graphite Electrodes. Here we demonstrate that gamma-butyrolactone (GBL) also exhibits suppressive effect on the intercalation of PF 6 − into the interlayer space between the graphene planes. The intercalation process of PF 6 − into Graphite Electrode from GBL has been investigated by in situ XRD, in situ Raman and EQCM. Furthermore, the effect of GBL has been compared with those of EC and propylene carbonate (PC).
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solvation effect on intercalation behaviour of tetrafluoroborate into Graphite Electrode
Journal of Power Sources, 2015Co-Authors: Masaki Yoshio, Li Qi, Hongyu WangAbstract:Abstract Anion-intercalated Graphite compounds are becoming attractive as high-potential positive Electrode materials in some electric energy storage devices. The intercalation of anions from electrolyte solutions to Graphite Electrode generally involves the co-entrance of organic solvent molecules inside the interlayer galleries of Graphite, which has a great impact on the electrochemical behaviour of the Graphite Electrode. In situ XRD (X-ray diffraction) and EQCM (Electrochemical quartz crystal microbalance) techniques have been corporately employed to investigate the mechanism of BF 4 − intercalation into Graphite positive Electrode from three electrolyte solutions in activated carbon/Graphite capacitors. The solvation states of BF 4 − by different solvents inside the Graphite Electrode have been correlated with the performance of AC/Graphite capacitors using corresponding electrolyte solutions.
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Solvation effect on intercalation behaviour of tetrafluoroborate into Graphite Electrode
Journal of Power Sources, 2015Co-Authors: Jichao Gao, Masaki Yoshio, Li Qi, Hongyu WangAbstract:(Figure Presented) Anion-intercalated Graphite compounds are becoming attractive as high-potential positive Electrode materials in some electric energy storage devices. The intercalation of anions from electrolyte solutions to Graphite Electrode generally involves the co-entrance of organic solvent molecules inside the interlayer galleries of Graphite, which has a great impact on the electrochemical behaviour of the Graphite Electrode. In situ XRD (X-ray diffraction) and EQCM (Electrochemical quartz crystal microbalance) techniques have been corporately employed to investigate the mechanism of BF4- intercalation into Graphite positive Electrode from three electrolyte solutions in activated carbon/Graphite capacitors. The solvation states of BF4- by different solvents inside the Graphite Electrode have been correlated with the performance of AC/Graphite capacitors using corresponding electrolyte solutions.
