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Year: 2002

Measurements of chemical warfare agent degradation products using an electrophoresis microchip with contactless conductivity

This paper reports on a microfluidic device for the screening of organophosphonate nerve agent degradation products. The miniaturized system relies on an efficient chip-based separation of alkyl methylphosphonic acids (breakdown products of Satin, Soman, and VX nerve agents) followed by their sensitive contactless conductivity detection. Experimental parameters relevant to the separation and detection processes have …

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Dual conductivity/amperometric detection system for microchip capillary electrophoresis

The performance characteristics and advantages of a new dual electrochemical microchip detection system based on simultaneous conductivity and amperometric measurements are described. The system relies on the combination of a contactless conductivity detector with an end-column thick-film amperometric detector. Such coupling of the conductivity and amperometric detection modes in a single separation channel greatly enhances …

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Thick-film electrochemical detectors for poly(dimethylsiloxane)based microchip capillary electrophoresis

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 …

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Chiral analysis of biogenic DL-amino acids derivatized by urethane – protected alpha-amino acid N-carboxyanhydride using capillary zone electrophoresis and micellar electrokinetic chromatography

A new analytical method for enantioselective separation of DL-amino acids derivatized by N-fluorenylmethoxycarbonyl-L-alanyl N-carboxyanhydride (FMOC-L-Ala-NCA) using capillary electrophoresis was developed. Separation parameters, such as composition and pH of the background electrolyte, and concentration of gamma-cyclodextrin (in capillary zone electrophoresis) and sodium dodecyl sulfate (in micellar electrokinetic chromatography) were optimized. The separation method was validated and …

Chiral analysis of biogenic DL-amino acids derivatized by urethane – protected alpha-amino acid N-carboxyanhydride using capillary zone electrophoresis and micellar electrokinetic chromatography Read More »

A chip-based capillary electrophoresis-contactless conductivity microsystem for fast measurements of low-explosive ionic components

A miniaturized analytical system for separating and detecting inorganic explosive residues, based on the coupling of a micromachined capillary electrophoresis (CE) chip with a contactless conductivity detector is described. The low electroosmotic flow (EOF) of the poly(methylmethacrylate) (PMMA) chip material facilitates the rapid switching between analyses of cations and anions using the same microchannel and …

A chip-based capillary electrophoresis-contactless conductivity microsystem for fast measurements of low-explosive ionic components Read More »

Non-aqueous capillary electrophoretic separation and detection of 6H-pyrimido[2,1-a]isoindoles

A non-aqueous capillary electrophoresis system for separating and detecting antidepressant drugs based on the coupling of capillary electrophoresis separation in acetonitrile and UV detection is described. The system offers a rapid simultaneous measurement in less than 12 min for six priority pyrimidoisoindoles. These antidepressants were detected down to the 2.5 x 10(-6)-4.2 x 10(-6) mol/L …

Non-aqueous capillary electrophoretic separation and detection of 6H-pyrimido[2,1-a]isoindoles Read More »

Contactless conductivity detector for microchip capillary electrophoresis

A microfabricated electrophoresis chip with an integrated contactless conductivity detection system is described. The new contactless conductivity microchip detector is based on placing two planar sensing aluminum film electrodes on the outer side of a poly(methyl methacrylate) (PMMA) microchip (without contacting the solution) and measuring the impedance of the solution in the separation channel. The …

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Capillary electrophoresis-electrochemistry microfluidic system for the determination of organic peroxides

A microfluidic analytical system for the separation and detection of organic peroxides. based on a microchip capillary electrophoresis device with an integrated amperometric detector. was developed. The new microsystem relies on the reductive detection of both organic acid peroxides and hydroperoxides at -700 mV (vs. Ag wire/AgCl). Factors influencing the separation and detection processes were …

Capillary electrophoresis-electrochemistry microfluidic system for the determination of organic peroxides Read More »

Single-channel microchip for fast screening and detailed identification of nitroaromatic explosives or organophosphate nerve agents

A single-channel chip-based analytical microsystem that allows rapid flow injection measurements of the total content of organic explosive or nerve agent compounds, as well as detailed micellar chromatographic identification of the individual ones, is described. The protocol involves repetitive rapid flow injection (screening) assays to provide a timely warning and alarm-and switching to the separation …

Single-channel microchip for fast screening and detailed identification of nitroaromatic explosives or organophosphate nerve agents Read More »

Towards disposable lab-on-a-chip: Poly(methylmethacrylate) microchip electrophoresis device with electrochemical detection

A fully disposable microanalytical device based on combination of poly(methylmethacrylate) (PMMA) capillary electrophoresis microchips and thick-film electrochemical detector strips is described. Variables influencing the separation efficiency and amperometric response, including separation voltage or detection potential are assessed and optimized. The versatility, simplicity and low-cost advantages of the new design are coupled to an attractive analytical …

Towards disposable lab-on-a-chip: Poly(methylmethacrylate) microchip electrophoresis device with electrochemical detection Read More »

beta-cyclodextrin-modified monolithic stationary phases for capillary electrochromatography and NANO-HPLC chiral analysis of ephedrine and ibuprofen

Chiral monolithic capillary columns for reversed-phase capillary electrochromatography (CEC) and for nano-HPLC were prepared by linking beta-cyclodextrin modifier into the acrylic monolithic phase. Columns with the physically and chemically bonded beta-cyclodextrin derivatives were tested under CEC and nano-HPLC conditions; enatioselective separation of (-)-ephedrine/ (+)-pseudoephedrine and (+/-)-ibuprofen was successfully performed. The separation efficiency of CEC and …

beta-cyclodextrin-modified monolithic stationary phases for capillary electrochromatography and NANO-HPLC chiral analysis of ephedrine and ibuprofen Read More »

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