The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Wei Qin - One of the best experts on this subject based on the ideXlab platform.
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alternative coulometric signal readout based on a solid contact ion Selective Electrode for detection of nitrate
Analytica Chimica Acta, 2020Co-Authors: Hemin Wang, Tanji Yin, Baiqing Yuan, Wei QinAbstract:Abstract Traditional potentiometric NO3−-Selective Electrodes suffer from a fundamental limitation of the Nernst slope (59.1 mV/dec at 25 °C) due to the relationship between the potential and the logarithmic of ionic activity. Herein, a coulometric signal readout is proposed instead of the potentiometric response for detection of NO3− based on an ordered mesoporous carbon (OMC)-based solid-contact ion-Selective Electrode (ISE). The mechanism for obtaining the coulometric signal is based on the electrical double layer capacitance of OMC compensating the potential change at the ion-Selective membrane/solution interface during the measurements under the control of a constant applied potential. Under the optimized conditions, the coulometric signal for the OMC-based solid-contact NO3−-ISE shows two linear responses in the activity range of 1.0 × 10−6-8.0 × 10−6 M and 8.0 × 10−6-8.0 × 10−4 M, and the detection limit is 4.0 × 10−7 M (3σ/s). The proposed coulometric response also shows excellent reproducibility and stability in the presence of O2 and CO2 and light on/off. Additionally, the coulometric response shows acceptable and reliable results for detection of NO3− in mineral water as compared to the traditional potentiometric response and the ion chromatography. This work provides a promising alternative signal readout for detection of ions by using solid-contact ion-Selective Electrodes.
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sequential and Selective detection of two molecules with a single solid contact chronopotentiometric ion Selective Electrode
Analytical Chemistry, 2018Co-Authors: Jiawang Ding, Xuedong Wang, Wei QinAbstract:A polymeric membrane ion-Selective Electrode (ISE) is typically designed for determination of one specific ion using conventional method. In this work, we demonstrate a simple, versatile and sensitive platform for simultaneous detection of two molecules with a single ISE. Under a series of periodic galvanostatic polarization, a solid-contact ISE without ion exchanger properties under zero-current conditions has been successfully used for simultaneous detection of two opposite charged ions with high sensitivity, good selectivity and fast reversibility. By integration of biorecognition elements with the potentiometric measurement, highly sensitive and Selective detection of a broad range of different molecular targets can be predicted. As a proof of concept, a potentiometric genosensor based on magnetic beads-enzyme sandwich assay has been designed for sensitive and Selective detection of pathogenic bacteria Escherichia coli O157:H7 and Staphylococcus aureus. Under optimal conditions, two bacteria nucleic a...
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a solid contact potassium Selective Electrode with moo2 microspheres as ion to electron transducer
Analytica Chimica Acta, 2017Co-Authors: Xianzhong Zeng, Wei QinAbstract:Abstract A solid-contact ion-Selective Electrode (SC-ISE) for potassium with MoO2 microspheres as ion-to-electron transducer is described. MoO2 microsphers can be synthesized via the reduction of MoO3 nanobelts in an isopropanol solvent with a mild process, and the obtained MoO2 microspheres have been characterized by X-ray diffraction and field-emission scanning electron microscopy. With the application of MoO2 microspheres, the newly fabricated SC-ISE for K+ exhibits a stable and rapid potential response. A near Nernstian slope of 55 mV/decade to potassium activities in the range of 10−5 ‒ 10−3 M is found and the detection limit is 10−5.5 M. Impedance spectra and chronopotentiometry results show that a smaller resistance together with a larger double layer capacitance is guaranteed due to the introduction of the intermediate layer of MoO2 microspheres. Additionally, light, O2 and CO2 do not induce significant influences to the present SC-ISE, and a reduced water layer between the ion Selective membrane and the underlying conductor is formed. Thus, it is clear that MoO2 microspheres, as metallic analogues, can be used as a good candidate for the new type of transducing layer in SC-ISEs.
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pulsed galvanostatic control of a solid contact ion Selective Electrode for potentiometric biosensing of microcystin lr
Sensors and Actuators B-chemical, 2016Co-Authors: Jiawang Ding, Xuedong Wang, Wenwei Wang, Wei QinAbstract:We report here on the development of a chronopotentiometric assay for microcystin-LR based on enzymatic inhibition. The inhibition of protein phosphatase by microcystin-LR can be sensed potentiometrically by using 4-nitrophenyl phosphate as an enzyme substrate. A solid-contact ion-Selective Electrode (ISE) with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) as a transduction layer has been designed for potentiometric biosensing using the pulsed galvanastatic technique. By applying an anodic current, the enzymatic generated p-nitrophenol can be extracted into the polymeric membrane with tetradodecylammonium tetrakis(4-chlorophenyl)-borate to produce the chronopotentiometric signal. Meanwhile, a controlled voltage was applied to refresh the membrane for multiple consecutive measurements. The proposed potentiometric assay showed a linear response for microcystin-LR in the range 1-100 mu g/L with a detection limit of 0.5 mu g/L (3 sigma). We believe that the proposed method can be employed for sensitive, rapid and reliable determination of analytes involved in enzyme inhibition. (C) 2016 Elsevier B.V. All rights reserved.
Andrzej Lewenstam - One of the best experts on this subject based on the ideXlab platform.
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A Breakthrough Application of a Cross-Linked Polystyrene Anion-Exchange Membrane for a Hydrogencarbonate Ion-Selective Electrode.
Sensors (Basel Switzerland), 2019Co-Authors: Sylwia Dabrowska, Jan Migdalski, Andrzej LewenstamAbstract:Polystyrene cross-linked with divinylbenzene and functionalized by a quaternary ammonium cation anion site is used as the membrane of a hydrogencarbonate (i.e., bicarbonate) ion-Selective Electrode. The polystyrene matrix membrane improves the selectivity towards interfering lipophilic ions in comparison to previously described polyvinyl chloride membranes. The reason for this behaviour is sought in coupled ion-exchange and pore-diffusion processes in the membrane and the resulting kinetic discrimination of interfering ions. The Electrode is successfully used for determination of bicarbonates in mineral drinking waters. The simplex method is employed to refine the analytical outcome.
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plasticizer free all solid state potassium Selective Electrode based on poly 3 octylthiophene and valinomycin
Analytica Chimica Acta, 1999Co-Authors: Johan Bobacka, Ari Ivaska, Andrzej LewenstamAbstract:Abstract All-solid-state potassium-Selective Electrodes with plasticizer-free membranes were prepared by incorporation of valinomycin as the ionophore and potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as the lipophilic additive in a semiconducting conjugated polymer matrix of poly(3-octylthiophene). The membrane components were dissolved in chloroform and deposited on glassy carbon by solution casting resulting in all-solid-state potassium sensors. The analytical performance of the potassium sensors were studied by potentiometric measurements. Electrochemical impedance spectroscopy was used to obtain information about the charge transfer and double layer charging processes in the Electrodes. The results show that a plasticizer-free all-solid-state potassium-Selective Electrode can be prepared and that the electron transfer at the glassy carbon|membrane interface plays a significant role in the signal transduction.
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single piece all solid state ion Selective Electrode
Analytical Chemistry, 1995Co-Authors: Johan Bobacka, Ari Ivaska, Tom Lindfors, Mary Mccarrick, Andrzej LewenstamAbstract:A novel concept of a single-piece all-solid-state ion-Selective Electrode (SPE) is introduced. A processable conjugated (electronically conducting or semiconducting) polymer (CP) is dissolved in a cocktail containing the components used for a conventional ion-Selective poly(vinyl chloride) matrix membrane. The cocktail, containing the CP, is cast directly on a solid substrate (glassy carbon), resulting in a SPE. The role of the CP is to mediate the charge transfer between the substrate and the membrane. Two soluble CPs are studied : (i) poly(3-octylthiophene) in its undoped state and (ii) polyaniline doped (protonated) with bis(2-ethylhexyl) hydrogen phosphate. Experimental results obtained for lithium-Selective SPEs and calcium-Selective SPEs are discussed. All the SPEs studied show near-Nernstian responses, and no redox interference is observed as long as the concentration of the CP is sufficiently low. The incorporation of a CP, particularly polyaniline, in the membrane is shown to improve the stability of the standard potential of the SPE compared to the corresponding coated-wire Electrode (membrane without CP). Impedance measurements provide information about the charge transfer processes of the Electrodes.
Johan Bobacka - One of the best experts on this subject based on the ideXlab platform.
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determination of calcium with ion Selective Electrode in black liquor from a kraft pulping process
Electroanalysis, 2009Co-Authors: Kim Granholm, Leo Harju, Tomasz Sokalski, Paul Ek, Johan Bobacka, Ari IvaskaAbstract:A solid-contact Ca 2þ -Selective Electrode was used to study speciation of calcium in black liquor. During extended time of operation the standard potential was found to change, but the sensitivity of the Electrode, and the selectivity coefficients remained unchanged. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) measurements showed sodium sorption to the Electrode membrane during the measurement in black liquor. Linearization of the complexometric titration curves were used to determine the concentrations of Ca 2þ , CaOH þ as well as weak and strong calcium complexes. With inductively coupled plasma optical emission spectrometry (ICPOES), similar total calcium concentrations were obtained as by the EDTA titration.
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plasticizer free all solid state potassium Selective Electrode based on poly 3 octylthiophene and valinomycin
Analytica Chimica Acta, 1999Co-Authors: Johan Bobacka, Ari Ivaska, Andrzej LewenstamAbstract:Abstract All-solid-state potassium-Selective Electrodes with plasticizer-free membranes were prepared by incorporation of valinomycin as the ionophore and potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as the lipophilic additive in a semiconducting conjugated polymer matrix of poly(3-octylthiophene). The membrane components were dissolved in chloroform and deposited on glassy carbon by solution casting resulting in all-solid-state potassium sensors. The analytical performance of the potassium sensors were studied by potentiometric measurements. Electrochemical impedance spectroscopy was used to obtain information about the charge transfer and double layer charging processes in the Electrodes. The results show that a plasticizer-free all-solid-state potassium-Selective Electrode can be prepared and that the electron transfer at the glassy carbon|membrane interface plays a significant role in the signal transduction.
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single piece all solid state ion Selective Electrode
Analytical Chemistry, 1995Co-Authors: Johan Bobacka, Ari Ivaska, Tom Lindfors, Mary Mccarrick, Andrzej LewenstamAbstract:A novel concept of a single-piece all-solid-state ion-Selective Electrode (SPE) is introduced. A processable conjugated (electronically conducting or semiconducting) polymer (CP) is dissolved in a cocktail containing the components used for a conventional ion-Selective poly(vinyl chloride) matrix membrane. The cocktail, containing the CP, is cast directly on a solid substrate (glassy carbon), resulting in a SPE. The role of the CP is to mediate the charge transfer between the substrate and the membrane. Two soluble CPs are studied : (i) poly(3-octylthiophene) in its undoped state and (ii) polyaniline doped (protonated) with bis(2-ethylhexyl) hydrogen phosphate. Experimental results obtained for lithium-Selective SPEs and calcium-Selective SPEs are discussed. All the SPEs studied show near-Nernstian responses, and no redox interference is observed as long as the concentration of the CP is sufficiently low. The incorporation of a CP, particularly polyaniline, in the membrane is shown to improve the stability of the standard potential of the SPE compared to the corresponding coated-wire Electrode (membrane without CP). Impedance measurements provide information about the charge transfer processes of the Electrodes.
Tanji Yin - One of the best experts on this subject based on the ideXlab platform.
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alternative coulometric signal readout based on a solid contact ion Selective Electrode for detection of nitrate
Analytica Chimica Acta, 2020Co-Authors: Hemin Wang, Tanji Yin, Baiqing Yuan, Wei QinAbstract:Abstract Traditional potentiometric NO3−-Selective Electrodes suffer from a fundamental limitation of the Nernst slope (59.1 mV/dec at 25 °C) due to the relationship between the potential and the logarithmic of ionic activity. Herein, a coulometric signal readout is proposed instead of the potentiometric response for detection of NO3− based on an ordered mesoporous carbon (OMC)-based solid-contact ion-Selective Electrode (ISE). The mechanism for obtaining the coulometric signal is based on the electrical double layer capacitance of OMC compensating the potential change at the ion-Selective membrane/solution interface during the measurements under the control of a constant applied potential. Under the optimized conditions, the coulometric signal for the OMC-based solid-contact NO3−-ISE shows two linear responses in the activity range of 1.0 × 10−6-8.0 × 10−6 M and 8.0 × 10−6-8.0 × 10−4 M, and the detection limit is 4.0 × 10−7 M (3σ/s). The proposed coulometric response also shows excellent reproducibility and stability in the presence of O2 and CO2 and light on/off. Additionally, the coulometric response shows acceptable and reliable results for detection of NO3− in mineral water as compared to the traditional potentiometric response and the ion chromatography. This work provides a promising alternative signal readout for detection of ions by using solid-contact ion-Selective Electrodes.
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an effective solid contact for an all solid state polymeric membrane cd2 Selective Electrode three dimensional porous graphene mesoporous platinum nanoparticle composite
Sensors and Actuators B-chemical, 2017Co-Authors: Tanji YinAbstract:Abstract The three-dimensional porous graphene-mesoporous platinum nanoparticle (3D PGR-MPN) composite is used as solid contact for developing an all-solid-state polymeric membrane Cd2+ ion-Selective Electrode (Cd2+-ISE). The 3D PGR with MPNs as cross-linking sites can be synthesized by a facile hydrothermal co-assembly method. The obtained 3D PGR-MPN composite is promising for acting as solid contact due to its unique characteristics such as high interfacial area, superior double layer capacitance, excellent conductivity and high hydrophobicity. The ISE exhibits a stable Nernstian response in the range of 10−8–10−4 M and the detection limit is 10−8.8 M. The 3D PGR-MPN-based Cd2+-ISE shows good potential response and no water layer exists between the polymeric membrane and the 3D PGR-MPN layer. Additionally, the proposed Cd2+-ISE is robust to O2, CO2 and light interferences. This work provides a versatile method for preparing an effective solid contact to develop a stable and reliable all-solid-state ISE.
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an all solid state polymeric membrane pb2 Selective Electrode with bimodal pore c 60 as solid contact
Analytica Chimica Acta, 2015Co-Authors: Tanji YinAbstract:An all-solid-state polymeric membrane Pb2+ ion-Selective Electrode (Pb2+-ISE) based on bimodal pore C-60 (BP-C-60) as solid contact has been developed. A BP-C-60 film can be readily formed on the surface of a glassy carbon Electrode by electrochemical deposition. Cyclic voltammetry and electrochemical impedance spectroscopy have been employed to characterize the BP-C-60 film. The large double layer capacitance and fast charge-transfer capability make BP-C-60 favorable to be used as solid contact for developing all-solid-state ISEs. The all-solid-state BP-C-60-based Pb2+-ISE shows a Nernstian response in the range from 1.0 x 10 (9) to 1.0 x 10 (3) M with a detection limit of 5.0 x 10 (10) M. The membrane Electrode not only displays an excellent potential stability with the absence of a water layer between the ion-Selective membrane and the underlying BP-C-60 solid contact, but also is insensitive to interferences from O-2, CO2 and light. The proposed solid-contact Pb2+-ISE has been applied to determine Pb2+ in real water samples and the results agree well with those obtained by anodic stripping voltammetry. (C) 2015 Elsevier B.V. All rights reserved.
Li Niu - One of the best experts on this subject based on the ideXlab platform.
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all solid state potassium Selective Electrode using graphene as the solid contact
Analyst, 2012Co-Authors: Min Zhou, Shiyu Gan, Qixian Zhang, Dongxue Han, Li NiuAbstract:Graphene sheets are used for the first time to fabricate a new type of solid-contact ion-Selective Electrode (SC-ISE) as the intermediate layer between an ionophore-doped solvent polymeric membrane and a glassy carbon Electrode. The new transducing layer was characterized by transmission electron microscopy, scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The performance of the new K+−Selective Electrodes was examined by a potentiometric water layer test, potentiometric measurements, and current reversal chronopotentiometry. The obtained potentiometric sensors were characterized with a calibration line of slope close to Nernstian (59.2 mV/decade) within the activity from 10−4.5 to 0.1 M. The high capacitance of the graphene solid contacts results in a signal that is stable over one week. The short response time is less than 10 s for activities higher than 10−5 M. The potential drift of the Electrodes was calculated from the slope of the curves at longer times (ΔE/Δt = 1.2 × 10−5 V s−1 (I = 1 nA) and ΔE/Δt = 5.5 × 10−5 V s−1 (I = 5 nA)). All the results indicate that graphene is a promising material for use as a transducer layer for SC-ISEs.
