The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
F. Gaillard - One of the best experts on this subject based on the ideXlab platform.
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Electrochemical characterisation of the Pt/YSZ interface exposed to a reactive gas phase
Solid State Ionics, 2004Co-Authors: Laurence Bultel, Claude Roux, Elisabeth Siebert, Philippe Vernoux, F. GaillardAbstract:The Pt/yttria-stabilized cubic zirconia (YSZ) interface exposed to a reactive gas was characterised by solid electrolyte Potentiometry and cyclic voltammetry. The catalytic reactions included total combustion of C3H8 and C3H6 to CO2 and H2O as well as NO reduction by C3H6 in the presence of O2 under oxygen-rich and stoichiometric conditions. The solid electrolyte Potentiometry as a function of the temperature in C3Hx/O2 (with x=6 or 8) reflected the catalytic properties of Pt for C3Hx oxidation. In C3H6/NO/O2, the reduction of NO was evidenced below 300 °C. The cyclic voltammetry evidenced the formation of an oxygen chemisorbed layer on the Pt surface under anodic potential. Propane had no effect on this chemisorbed layer, whereas propene weakened significantly the strength of this Pt–O bond. Addition of NO to C3H6/O2 led to the disappearing of this chemisorbed layer. The use of solid electrolyte Potentiometry in conjunction with cyclic voltammetry allowed us to determine the surface oxidation state of Pt during the catalytic reactions.
Eric Bakker - One of the best experts on this subject based on the ideXlab platform.
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Phenytoin speciation with potentiometric and chronopotentiometric ion-selective membrane electrodes
Biosensors & bioelectronics, 2015Co-Authors: Sutida Jansod, Gastón A. Crespo, Majid Ghahraman Afshar, Eric BakkerAbstract:We report on an electrochemical protocol based on perm-selective membranes to provide valuable information about the speciation of ionizable drugs, with phenytoin as a model example. Membranes containing varying amounts of tetradodecylammonium chloride (TDDA) were read out at zero current (Potentiometry) and with applied current techniques (chronoPotentiometry). Potentiometry allows one to assess the ionized form of phenytoin (pKa~8.2) that corresponds to a negatively monocharged ion. A careful optimization of the membrane components resulted in a lower limit of detection (~1.6 µM) than previous reports. Once the pH (from 9 to 10) or the concentration of albumin is varied in the sample (from 0 to 30 g L(-1)), the potentiometric signal changes abruptly as a result of reducing/increasing the ionized concentration of phenytoin. Therefore, Potentiometry as a single technique is by itself not sufficient to obtain information about the concentration and speciation of the drug in the system. For this reason, a tandem configuration with chronoPotentiometry as additional readout principle was used to determine the total and ionized concentration of phenytoin. In samples containing excess albumin the rate-limiting step for the chronoPotentiometry readout appears to be the diffusion of ionized phenytoin preceded by comparatively rapid deprotonation and decomplexation reactions. This protocol was applied to measure phenytoin in pharmaceutical tables (100mg per tablet). This tandem approach can likely be extended to more ionizable drugs and may eventually be utilized in view of pharmacological monitoring of drugs during the delivery process.
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Modern Potentiometry.
Angewandte Chemie (International ed. in English), 2007Co-Authors: Eric Bakker, Ernö PretschAbstract:For most chemists, Potentiometry with ion-selective electrodes (ISEs) primarily means pH measurements with a glass electrode. Those interested in clinical analysis might know that ISEs, routinely used for the determination of blood electrolytes, have a market size comparable to that of glass electrodes. It is even less well known that Potentiometry went through a silent revolution during the past decade. The lower detection limit and the discrimination of interfering ions (the selectivity coefficients) have been improved in many cases by factors up to 10(6) and 10(10), respectively, thus allowing their application in fields such as environmental trace analysis and potentiometric biosensing. The determination of complex formation constants for lipophilic hosts and ionic guests is also covered in this Minireview.
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Backside Calibration Potentiometry: Ion Activity Measurements with Selective Supported Liquid Membranes by Calibrating from the Inner Side of the Membrane
Analytical chemistry, 2007Co-Authors: Adam Malon, Eric Bakker, Ernö PretschAbstract:In direct Potentiometry, the magnitude of the measured potentials is used to determine the composition of the sample. While this places rather formidable demands on the required reproducibility of the associated potential measurements, typically on the order of microvolts, in vitro clinical analyses of blood samples are today successfully performed with direct Potentiometry using ion-selective electrodes (ISEs). Unfortunately, most other analytical situations do not permit the sensor to be recalibrated every few minutes, as in environmental monitoring or in vivo measurements, and direct Potentiometry is often bound to fail as an accurate method in these circumstances. This paper introduces a novel direction for potentiometric sensing, termed backside calibration Potentiometry. Chemical asymmetries across thin supported liquid ISE membranes are assessed by determining the direction of potential drift upon changing the stirring rate on either side of the membrane. Disappearance of this drift indicates the d...
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Potentiometry at trace levels
Trends in Analytical Chemistry, 2001Co-Authors: Eric Bakker, Ernö PretschAbstract:Recently, it was realized that polymeric membrane ion-selective electrodes can be optimized to show dramatically improved detection limits over traditional values. This discovery has initiated much excitement in the chemical sensor community, since it appears that the applicability of ion-selective electrodes in chemical analysis has been very much underestimated in the past. While this is a rather new research area, some significant progress has already been made to understand important basic processes that dictate the response behavior of ISEs under dilute sample conditions. This review summarizes these developments from basic considerations to practical applications. It outlines the current state of the art of this research and the long-term promises that this technology holds.
Susana Palmero - One of the best experts on this subject based on the ideXlab platform.
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Analysis and speciation of arsenic by stripping Potentiometry: a review.
Talanta, 2004Co-Authors: Emma Muñoz, Susana PalmeroAbstract:This paper provides a review that summarizes several examples of the literature from 1980 to 2003, to illustrate the applications of stripping Potentiometry for the determination and speciation of arsenic in several samples. A discussion on the main advantages of stripping Potentiometry in comparison with other electrochemical methods employed for arsenic determination is presented. Special attention is devoted to stripping modes (constant current or chemical stripping) and to issues related to the choice of working electrodes and supporting electrolyte. This approach has been also applied at arsenic determination in flow systems. A section is dedicated to speciation of arsenic and total arsenic determination and other to analytical characteristic of method and their interferences. An extensive compilation, organize by experimental and analytical parameters and real sample studied is presented.
Laurence Bultel - One of the best experts on this subject based on the ideXlab platform.
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Electrochemical characterisation of the Pt/YSZ interface exposed to a reactive gas phase
Solid State Ionics, 2004Co-Authors: Laurence Bultel, Claude Roux, Elisabeth Siebert, Philippe Vernoux, F. GaillardAbstract:The Pt/yttria-stabilized cubic zirconia (YSZ) interface exposed to a reactive gas was characterised by solid electrolyte Potentiometry and cyclic voltammetry. The catalytic reactions included total combustion of C3H8 and C3H6 to CO2 and H2O as well as NO reduction by C3H6 in the presence of O2 under oxygen-rich and stoichiometric conditions. The solid electrolyte Potentiometry as a function of the temperature in C3Hx/O2 (with x=6 or 8) reflected the catalytic properties of Pt for C3Hx oxidation. In C3H6/NO/O2, the reduction of NO was evidenced below 300 °C. The cyclic voltammetry evidenced the formation of an oxygen chemisorbed layer on the Pt surface under anodic potential. Propane had no effect on this chemisorbed layer, whereas propene weakened significantly the strength of this Pt–O bond. Addition of NO to C3H6/O2 led to the disappearing of this chemisorbed layer. The use of solid electrolyte Potentiometry in conjunction with cyclic voltammetry allowed us to determine the surface oxidation state of Pt during the catalytic reactions.
Ernö Pretsch - One of the best experts on this subject based on the ideXlab platform.
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Modern Potentiometry.
Angewandte Chemie (International ed. in English), 2007Co-Authors: Eric Bakker, Ernö PretschAbstract:For most chemists, Potentiometry with ion-selective electrodes (ISEs) primarily means pH measurements with a glass electrode. Those interested in clinical analysis might know that ISEs, routinely used for the determination of blood electrolytes, have a market size comparable to that of glass electrodes. It is even less well known that Potentiometry went through a silent revolution during the past decade. The lower detection limit and the discrimination of interfering ions (the selectivity coefficients) have been improved in many cases by factors up to 10(6) and 10(10), respectively, thus allowing their application in fields such as environmental trace analysis and potentiometric biosensing. The determination of complex formation constants for lipophilic hosts and ionic guests is also covered in this Minireview.
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Backside Calibration Potentiometry: Ion Activity Measurements with Selective Supported Liquid Membranes by Calibrating from the Inner Side of the Membrane
Analytical chemistry, 2007Co-Authors: Adam Malon, Eric Bakker, Ernö PretschAbstract:In direct Potentiometry, the magnitude of the measured potentials is used to determine the composition of the sample. While this places rather formidable demands on the required reproducibility of the associated potential measurements, typically on the order of microvolts, in vitro clinical analyses of blood samples are today successfully performed with direct Potentiometry using ion-selective electrodes (ISEs). Unfortunately, most other analytical situations do not permit the sensor to be recalibrated every few minutes, as in environmental monitoring or in vivo measurements, and direct Potentiometry is often bound to fail as an accurate method in these circumstances. This paper introduces a novel direction for potentiometric sensing, termed backside calibration Potentiometry. Chemical asymmetries across thin supported liquid ISE membranes are assessed by determining the direction of potential drift upon changing the stirring rate on either side of the membrane. Disappearance of this drift indicates the d...
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Potentiometry at trace levels
Trends in Analytical Chemistry, 2001Co-Authors: Eric Bakker, Ernö PretschAbstract:Recently, it was realized that polymeric membrane ion-selective electrodes can be optimized to show dramatically improved detection limits over traditional values. This discovery has initiated much excitement in the chemical sensor community, since it appears that the applicability of ion-selective electrodes in chemical analysis has been very much underestimated in the past. While this is a rather new research area, some significant progress has already been made to understand important basic processes that dictate the response behavior of ISEs under dilute sample conditions. This review summarizes these developments from basic considerations to practical applications. It outlines the current state of the art of this research and the long-term promises that this technology holds.