The Experts below are selected from a list of 1473 Experts worldwide ranked by ideXlab platform

Susan M. Lunte - One of the best experts on this subject based on the ideXlab platform.

  • Recent developments in electrochemical detection for Microchip Capillary Electrophoresis
    Electrophoresis, 2004
    Co-Authors: Walter R. Vandaveer Iv, Stephanie A. Pasas-farmer, David J. Fischer, Celeste N. Frankenfeld, Susan M. Lunte
    Abstract:

    Significant progress in the development of miniaturized microfluidic systems has occurred since their inception over a decade ago. This is primarily due to the numerous advantages of Microchip analysis, including the ability to analyze minute samples, speed of analysis, reduced cost and waste, and portability. This review focuses on recent developments in integrating electrochemical (EC) detection with Microchip Capillary Electrophoresis (CE). These detection modes include amperometry, conductimetry, and potentiometry. EC detection is ideal for use with Microchip CE systems because it can be easily miniaturized with no diminution in analytical performance. Advances in Microchip format, electrode material and design, decoupling of the detector from the separation field, and integration of sample preparation, separation, and detection on-chip are discussed. Microchip CEEC applications for enzyme/immunoassays, clinical and environmental assays, as well as the detection of neurotransmitters are also described.

  • in channel electrochemical detection for Microchip Capillary Electrophoresis using an electrically isolated potentiostat
    Analytical Chemistry, 2002
    Co-Authors: Scott R Martin, Kenneth L Ratzlaff, And Bryan H Huynh, Susan M. Lunte
    Abstract:

    A new electrode configuration for Microchip Capillary Electrophoresis (CE) with electrochemical (EC) detection is described. This approach makes it possible to place the working electrode directly in the separation channel. The “in-channel” EC detection was accomplished without the use of a decoupler through the utilization of a specially designed, electrically isolated potentiostat. The effect of the working electrode position on the separation performance (in terms of plate height and peak skew) of poly(dimethylsiloxane)-based Microchip CEEC devices was evaluated by comparing the more commonly used end-channel configuration with this new in-channel approach. Using catechol as the test analyte, it was found that in-channel EC detection decreased the total plate height by a factor of 4.6 and lowered the peak skew by a factor of 1.3. A similar trend was observed for the small, inorganic ion nitrite. Furthermore, a fluorescent and electrochemically active amino acid derivative was used to directly compare t...

  • Recent developments in amperometric detection for Microchip Capillary Electrophoresis
    Electrophoresis, 2002
    Co-Authors: Walter R. Vandaveer Iv, Stephanie A. Pasas, R. Scott Martin, Susan M. Lunte
    Abstract:

    The interest in microfluidic devices has increased considerably over the past decade due to the numerous advantages of working within a miniature, microfabricated format. This review focuses on recent advances in coupling amperometric detection with Microchip Capillary Electrophoresis (CE). Advances in electrochemical cell design, isolation of the detector from the separation field, and integration of both pre- and postseparation reaction chambers are discussed. The use of Microchip CE with amperometric detection for enzyme/immunoassays, clinical and environmental assays, and the determination of neurotransmitters is described.

  • Thick-film electrochemical detectors for poly(dimethylsiloxane)-based Microchip Capillary Electrophoresis
    Electroanalysis, 2002
    Co-Authors: Joseph Wang, R. Scott Martin, Martin Pumera, Madhu Prakash Chatrathi, Adrian T. Rodriguez, Scott D. Spillman, Susan M. Lunte
    Abstract:

    A new poly(dimethylsiloxane) (PDMS)-based Microchip Capillary Electrophoresis (CE) device, with a thick-film electrochemical detector, is described. The end-column design relies on screen-printing the amperometric carbon working electrode on the base plate of a PDMS Microchip (opposite to the exit of the microchannel). Since the channel depth and electrode height are quite similar, this is a flow-onto/flow-by hybrid arrangement. The influence of relevant experimental variables, such as the separation and detection potentials, is reported along with the attractive analytical performance. Flat baselines and extremely low noise levels are observed even at high separation fields (approaching 700 V/cm), reflecting the effective electrical isolation of the detector. The resulting detection limits (150 nM for epinephrine and 280 nM for catechol) compare favorably with those obtained by other PDMS-based electrochemical detectors. Such coupling of low-cost and versatile PDMS chips and thick-film electrochemical detectors holds great promise for high-volume production of disposable microfluidic analytical devices.

  • Microchip Capillary Electrophoresis electrochemistry
    Electrophoresis, 2001
    Co-Authors: Nathan A. Lacher, Kenneth E. Garrison, Scott R Martin, Susan M. Lunte
    Abstract:

    Microfabricated fluidic devices have generated considerable interest over the past ten years due to the fact that sample preparation, injection, separation, derivatization, and detection can be integrated into one miniaturized device. This review reports progress in the development of microfabricated analytical systems based on Microchip Capillary Electrophoresis (CE) with electrochemical (EC) detection. Electrochemical detection has several advantages for use with Microchip Electrophoresis systems, for example, ease of miniaturization, sensitivity, and selectivity. In this review, the basic components necessary for Microchip CEEC are described, including several examples of different detector configurations. Lastly, details of the application of this technique to the determination of catechols and phenols, amino acids, peptides, carbohydrates, nitroaromatics, polymerase chain reaction (PCR) products, organophosphates, and hydrazines are described.

Salvador Alegret - One of the best experts on this subject based on the ideXlab platform.

Martin Pumera - One of the best experts on this subject based on the ideXlab platform.

  • Microchip Capillary Electrophoresis with a Single-Wall Carbon Nanotube/Gold Electrochemical Detector for Determination of Aminophenols and Neurotransmitters
    Microchimica Acta, 2006
    Co-Authors: Martin Pumera, Xavier Llopis, Arben Merkoçi, Salvador Alegret
    Abstract:

    A new SWCNT modified gold detector for Microchip Capillary Electrophoresis–electrochemistry is described. SWCNT modified gold electrode displays greatly improved sensitivity and separation resolution compared to bare gold electrode, reflecting the electrocatalytic activity of SWCNT. The SWCNT/Au electrode exhibits low background noise levels. Parameters such as separation voltage and detection potential of the Microchip Electrophoresis–electrochemistry with SWCNT modified gold electrode were optimized.

  • Microchip Capillary Electrophoresis with a single wall carbon nanotube gold electrochemical detector for determination of aminophenols and neurotransmitters
    Mikrochimica Acta, 2006
    Co-Authors: Martin Pumera, Xavier Llopis, Arben Merkoçi, Salvador Alegret
    Abstract:

    A new SWCNT modified gold detector for Microchip Capillary Electrophoresis–electrochemistry is described. SWCNT modified gold electrode displays greatly improved sensitivity and separation resolution compared to bare gold electrode, reflecting the electrocatalytic activity of SWCNT. The SWCNT/Au electrode exhibits low background noise levels. Parameters such as separation voltage and detection potential of the Microchip Electrophoresis–electrochemistry with SWCNT modified gold electrode were optimized.

  • Thick-film electrochemical detectors for poly(dimethylsiloxane)-based Microchip Capillary Electrophoresis
    Electroanalysis, 2002
    Co-Authors: Joseph Wang, R. Scott Martin, Martin Pumera, Madhu Prakash Chatrathi, Adrian T. Rodriguez, Scott D. Spillman, Susan M. Lunte
    Abstract:

    A new poly(dimethylsiloxane) (PDMS)-based Microchip Capillary Electrophoresis (CE) device, with a thick-film electrochemical detector, is described. The end-column design relies on screen-printing the amperometric carbon working electrode on the base plate of a PDMS Microchip (opposite to the exit of the microchannel). Since the channel depth and electrode height are quite similar, this is a flow-onto/flow-by hybrid arrangement. The influence of relevant experimental variables, such as the separation and detection potentials, is reported along with the attractive analytical performance. Flat baselines and extremely low noise levels are observed even at high separation fields (approaching 700 V/cm), reflecting the effective electrical isolation of the detector. The resulting detection limits (150 nM for epinephrine and 280 nM for catechol) compare favorably with those obtained by other PDMS-based electrochemical detectors. Such coupling of low-cost and versatile PDMS chips and thick-film electrochemical detectors holds great promise for high-volume production of disposable microfluidic analytical devices.

Walter R. Vandaveer Iv - One of the best experts on this subject based on the ideXlab platform.

  • Recent developments in electrochemical detection for Microchip Capillary Electrophoresis
    Electrophoresis, 2004
    Co-Authors: Walter R. Vandaveer Iv, Stephanie A. Pasas-farmer, David J. Fischer, Celeste N. Frankenfeld, Susan M. Lunte
    Abstract:

    Significant progress in the development of miniaturized microfluidic systems has occurred since their inception over a decade ago. This is primarily due to the numerous advantages of Microchip analysis, including the ability to analyze minute samples, speed of analysis, reduced cost and waste, and portability. This review focuses on recent developments in integrating electrochemical (EC) detection with Microchip Capillary Electrophoresis (CE). These detection modes include amperometry, conductimetry, and potentiometry. EC detection is ideal for use with Microchip CE systems because it can be easily miniaturized with no diminution in analytical performance. Advances in Microchip format, electrode material and design, decoupling of the detector from the separation field, and integration of sample preparation, separation, and detection on-chip are discussed. Microchip CEEC applications for enzyme/immunoassays, clinical and environmental assays, as well as the detection of neurotransmitters are also described.

  • Recent developments in amperometric detection for Microchip Capillary Electrophoresis
    Electrophoresis, 2002
    Co-Authors: Walter R. Vandaveer Iv, Stephanie A. Pasas, R. Scott Martin, Susan M. Lunte
    Abstract:

    The interest in microfluidic devices has increased considerably over the past decade due to the numerous advantages of working within a miniature, microfabricated format. This review focuses on recent advances in coupling amperometric detection with Microchip Capillary Electrophoresis (CE). Advances in electrochemical cell design, isolation of the detector from the separation field, and integration of both pre- and postseparation reaction chambers are discussed. The use of Microchip CE with amperometric detection for enzyme/immunoassays, clinical and environmental assays, and the determination of neurotransmitters is described.

Joseph Wang - One of the best experts on this subject based on the ideXlab platform.

  • Wall-jet conductivity detector for Microchip Capillary Electrophoresis
    Talanta, 2009
    Co-Authors: Joseph Wang, Gang Chen, Alexander Muck
    Abstract:

    A new end-column 'hybrid' contactless conductivity detector for Microchip Capillary Electrophoresis (CE) was developed. It is based on a "hybrid" arrangement where the receiving electrode is insulated by a thin layer of insulator and placed in the bulk solution of the detection reservoir of the chip, whereas the emitting electrode is in contact with the solution eluted from the channel outlet in a wall-jet arrangement. The favorable features of the new detector including the high sensitivity and low noise, can be attributed to both the direct contact of the 'emitting' electrode with the analyte solution as well as to the insulation of the detection electrode from the high DC currents in the electrophoretic circuit. Such arrangement provides a 10-fold sensitivity enhancement compared to currently used on-column contactless conductivity CE Microchip detector as well as low values of noise and easy operation. The new design of the wall-jet conductivity detector was tested for separation of explosive-related methylammonium, ammonium, and sodium cations. The new detector design reconsiders the wall-jet arrangement for Microchip conductivity detection in scope of improved peak symmetry, simplified study of inter-electrode distance, isolation of the electrodes, position of the wall-jet electrode to the separation channel, baseline stability and low limits of detection.

  • carbon nanotube poly methyl methacrylate cnt pmma composite electrode fabricated by in situ polymerization for Microchip Capillary Electrophoresis
    Chemistry: A European Journal, 2007
    Co-Authors: Xiao Yao, Joseph Wang, Gang Chen
    Abstract:

    We describe the development and application of a novel carbon nanotube/poly(methyl methacrylate) (CNT/PMMA) composite electrode as a sensitive amperometric detector of Microchip Capillary Electrophoresis (CE). The composite electrode was fabricated by the in situ polymerization of a mixture of CNTs and prepolymerized methyl methacrylate in the microchannel of a piece of fused silica Capillary under heat. The performance of this unique system was demonstrated by the separation and detection of phenolic pollutants and purines. The new CNT-based CE detector offered significantly lower operating potentials, yielded substantially enhanced signal-to-noise characteristics, and exhibited resistance to surface fouling and, hence, enhanced stability. Long-term stability and reproducibility with relative standard deviations of less than 5 % for the peak current (n=20) were also demonstrated. The simplicity and significant performance exhibited by the CNT/PMMA composite electrode indicate great promise for conventional CE, flowing-injection analysis, and other microfluidic analysis systems.

  • monitoring environmental pollutants by Microchip Capillary Electrophoresis with electrochemical detection
    Talanta, 2006
    Co-Authors: Gang Chen, Joseph Wang
    Abstract:

    Abstract During the past decade, significant progress in the development of miniaturized microfluidic systems has occurred due to the numerous advantages of Microchip analysis. This review focuses on recent advances and the key strategies in Microchip Capillary Electrophoresis (CE) with electrochemical detection (ECD) for separating and detecting a variety of environmental pollutants. The subjects covered include the fabrication of microfluidic chips, ECD, typical applications of Microchip CE with ECD in environmental analysis, and future prospects. It is expected that Microchip CE–ECD will become a powerful tool in the environmental field and will lead to the creation of truly portable devices.

  • Microchip Capillary Electrophoresis with Electrochemical Detection for Monitoring Environmental Pollutants
    Current Analytical Chemistry, 2006
    Co-Authors: Gang Chen, Yuehe Lin, Joseph Wang
    Abstract:

    This invited paper reviews recent advances and the key strategies in Microchip Capillary Electrophoresis (CE) with electrochemical detection (ECD) for separating and detecting a variety of environmental pollutants. The subjects covered include the fabrication of microfluidic chips, sample pretreatments, ECD, typical applications of Microchip CE with ECD in environmental analysis, and future prospects. It is expected that Microchip CE-ECD will become a powerful tool in the environmental field and will lead to the creation of truly portable devices.

  • Microchip Capillary Electrophoresis with amperometric detection for rapid separation and detection of seleno amino acids.
    Journal of Chromatography A, 2005
    Co-Authors: Joseph Wang, Madhu Prakash Chatrathi, Matteo Scampicchio, Saverio Mannino, Carmen Camera, Jiri Zima
    Abstract:

    This article describes an effective Microchip Capillary-Electrophoresis protocol for rapid and effective measurements of food-related seleno amino acids, including Se-methionine (Se-Met), Se-ethionine (Se-Eth), Se-methyl cysteine (Se-Cys), utilizing o-phtaldialdeyde/2-mercaptoethanol (OPA/2-ME) derivatization. Relevant parameters of the chip separation and amperometric detection are examined and optimized using a response surface methodology (RSM). Under optimum conditions, the analytes could be separated and detected in a 30 mM borate buffer (pH 9.3, with 28 mM sodium dodecul sulfate) within 300 s using a separation voltage of 2000V and a detection voltage of +0.9 V. Linear calibration plots are observed for micromolar concentrations of the Se-amino acid compounds. The negligible sample volumes used in the Microchip procedure obviates surface fouling common to amperometric measurements of selenoamino-acid compounds. The new Microchip protocol offers great promise for a wide range of food applications requiring fast measurements and negligible sample consumption.