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  • 1
    Electronic Resource
    Electronic Resource
    Solid phase micro-extraction of metal ions (1993)
    Springer
    Microchimica acta 112 (1993), S. 41-46 
    Details
    ISSN: 1436-5073
    Keywords: solid phase microextraction ; liquid ion exchanger ; bismuth ; extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A fused silica fibre coated with poly(dimethylsiloxane) was modified to produce a micro probe with ion exchanging capability. The liquid ion exchanger, di-(2-ethylhexyl)phosphoric acid (HDEHP), was used for the modification. The probe was used for the extraction of bismuth(III) from aqueous nitric acid solution. The extracted Bi(III) was desorbed into an acidic potassium iodide solution. The yellow colored BiI4 − complex formed was determined by spectrophotometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01243319
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  • 2
    Electronic Resource
    Electronic Resource
    Fiber Conditioners for Solid Phase Microextraction: Design, Testing, and Application (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 343-347 
    Details
    ISSN: 0935-6304
    Keywords: SPME ; desorption ; fiber conditioning ; field sampling ; sample preparation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Inexpensive fluid delivery system for supercritical fluid extraction (1990)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 199-202 
    Details
    ISSN: 0935-6304
    Keywords: Supercritical fluid ; Pump ; Extraction ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240130316
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  • 4
    Electronic Resource
    Electronic Resource
    Quest for new sample preparation methods (1993)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 565-565 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240161002
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  • 5
    Electronic Resource
    Electronic Resource
    Ampholyte-free isoelectric focusing of proteins in cone shaped capillaries (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 5 (1993), S. 397-401 
    Details
    ISSN: 1040-7685
    Keywords: isoelectric focusing ; cone shaped capillaries ; pH gradient ; temperature gradient ; proteins ; absorption imaging detection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple method of generating pH gradients for use in capillary isoelectric focusing was described and evaluated experimentally. In the proposed scheme, the cone shaped capillary filled with a conventional buffer is used to produce an effect of nonuniform heating which then generate temperature and corresponding pH gradients along the capillary axis. Concentration and separation of proteins by applying a simple isoelectric focusing system based on this principle is demonstrated. An inexpensive absorption imaging detection system is used to continuously monitor progress of the separation and concentration processes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220050502
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  • 6
    Electronic Resource
    Electronic Resource
    Solvent-free sample introduction for supercritical fluid chromatography using polymer coated fibers (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 6 (1994), S. 443-447 
    Details
    ISSN: 1040-7685
    Keywords: supercritical fluid chromatography ; sample introduction ; solid phase microextraction ; polymer coated fibers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A solvent-free sample introduction method for supercritical fluid chromatography that uses polymer coated fused silica fibers results in very stable baseline and high efficiency separations. The method has two steps: first, a fiber is exposed to a prepared mixture of target analytes or a sample so that the polymeric coating absorbs analytes, and second, the fiber is placed inside a piece of tubing connected to the column of a supercritical fluid chromatograph. The supercritical fluid carrier extracts analytes from the coating and transfers them onto the head of the column. Pressure programmed separation follows. The method was tested on high molecular weight and polar analytes using 100 and 50 μm i.d. capillary columns. Fibers with a polydimethylsiloxane coating were used to extract hydrophobic analytes, and fibers with a polyacrylate coating were used to extract more polar compounds.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220060503
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  • 7
    Electronic Resource
    Electronic Resource
    Isoelectric focusing of proteins in a microcapillary with universal concentration gradient detection (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 4 (1992), S. 419-422 
    Details
    ISSN: 1040-7685
    Keywords: capillary isoelectric focusing ; microcapillary ; concentration gradient detector ; protein analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proteins were separated by capillary isoelectric focusing (CIEF) performed in a 5-μm i.d., 12-cm long uncoated capillary, and detected by an on-column concentration gradient detector based on Schlieren optics. The narrow capillary allows the application of a 15-kV separation voltage. The high voltage resulted in a very narrow 30-μm wide zone for carbonic anhydrase, which corresponded to a 60-fL zone volume. All focused proteins could be detected by the universal concentration gradient detector without derivatization in less than 7 min. On-column mass detection limits for proteins were at the 100 amol level, which was lower than that of a UV-vis absorption spectrometric detector. The detection volume of the detector was calculated to be 20 fL, the smallest detection volumes reported to date for optical or spectroscopic detectors. This microcapillary CIEF-concentration gradient detector system may be a useful technique for direct analysis of proteins at the single cell level.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220040509
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  • 8
    Electronic Resource
    Electronic Resource
    Solventless injection technique for microcolumn separations (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 5 (1993), S. 51-56 
    Details
    ISSN: 1040-7685
    Keywords: solid phase microextraction ; solventless injection ; thermal dersorption ; silica fiber ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermal desorption of analytes from a solid phase microextraction (SPME) device is the ideal techniques for sample introduction into microcolumns because the solvent is entirely eliminated. SPME is compatible with various injector designs, is independent of the instrument manufacturer, and can be completely automated. It can be used to concentrate the analytes from liquid, gaseous, or headspace samples with equal success. The location of the fiber in the injector for programmable direct and splitsplitless injectors are described since fiber positioning varies with injector design. An SPME injection consists of two parts: desorption in the injector followed by cryofocusing in the gas chromatographic column. The factors affecting desorption and cryofocusing, and the thickness of the column stationary phase. Example of fiber injections of liquid and gaseous samples are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220050108
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  • 9
    Electronic Resource
    Electronic Resource
    Supercritical fluid extraction and clean-up with temperature fractionation: Application to determination of polychlorinated dibenzo-ρ-dioxins (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 6 (1994), S. 459-465 
    Details
    ISSN: 1040-7685
    Keywords: supercritical fluid extraction ; sample clean-up ; temperature fractionation ; polychlorinated dibenzo-ρ-dioxins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Supercritical fluid extraction (SFE) and clean-up with neat carbon dioxide (CO2), selective sorbents and high extraction temperature was developed as a sample preparation method. The effects of temperature and pressure on SFE efficiencies were investigated by spiking a polychlorinated dibenzo-ρ-dioxin (PCDD)/polychlorinated biphenyl (PCB) standard mixture onto a Florisil™ adsorbent and extracting these compounds at different temperatures and pressures with neat CO2. High extraction temperatures and pressures were found to increase the extraction rate and efficiency. PCDDs were quantitatively extracted from Florisil™ only when the temperature was raised to 200°C and the pressure was 9000 psi. PCBs were efficiently extracted at low temperature and pressure, such as 50°C and 2000 psi. Fractionation of PCBs from PCDDs with Florisil™ using CO2 was accomplished by first quantitatively recovering all of the PCBs at 3500 psi and 80°C and then the dioxins at 9000 psi and 250°C.The determination of PCDDs in fly ash was carried out by spiking the fly ash extract (obtained after 80 min extraction at 250°C and 9400 psi using neat CO2) onto FlorislTM, followed by the clean-up step outlined above. This step produced much cleaner chromatograms compared to direct extraction. The modifier-free high temperature SFE method produced comparable results to 20 h Soxhlet extraction of fly ash, but it was shorter by an order of magnitude.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220060505
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  • 10
    Electronic Resource
    Electronic Resource
    Diode laser-based concentration gradient detector for capillary isotachophoresis (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 5 (1993), S. 217-222 
    Details
    ISSN: 1040-7685
    Keywords: capillary isotachophoresis ; diode laser ; concentration gradient detector ; universal detection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A diode laser-based, universal concentration gradient detector was applied to capillary isotachophoresis (CITP). The inexpensive CITP instrument also included a 30 cm long, 300 μm i.d. capillary, a 5 cm focal length lens and a photodiode light beam position sensor. Factors affecting the sensitivity and performance of the detector, i.e., separation conditions, spatial resolution of the detector, and the concentration of leading electrolyte, were discussed theoretically and experimentally. The diode laser-based concentration gradient detector appears to be one of the best detectors for CITP due to its high resolution, derivative nature, and low cost. The experimental detection limit reached 4 × 10-6 M for small cations, which was near the theoretical value. The detection limit can be further reduced by at least one order of magnitude if a longer capillary is used. The CITP-concentration gradient detector instrument has high efficiency, and was applied to detect impurities in antidepressant drugs.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220050306
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