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  • Flow injection analysis  (3)
  • Supercritical fluid extraction  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Systematic study of the influence of modifiers on the CO2-supercritical extraction of PAHs in soil (1994)
    Springer
    Chromatographia 38 (1994), S. 431-435 
    Details
    ISSN: 1612-1112
    Keywords: Supercritical fluid extraction ; PAHs ; Modifers ; Soil samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An exhaustive study of the behaviour in supercritical fluid extraction of eight PAHs in real samples of soil compared to spiked samples in silica has been carried out. The presence of a modifier is mandatory for quantitative extraction of the native analytes, but is unnecessary in spiked samples. The type and volume of modifier to be added and the sample-modifier contact time were optimized and the influence of the particle size assessed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269831
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Total and individual determination of carbamate pesticides by use of an integrated flow-injection/HPLC system (1992)
    Springer
    Chromatographia 33 (1992), S. 449-453 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flow injection analysis ; Combined flow injection/HPLC ; Carbamate pesticides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An integrated flow injection (FI)/HPLC system for the total and individual determination of carbamate pesticides (propoxur, carbofuran and carbaryl) is proposed. The determination is based on the alkaline hydrolysis of the analytes and subsequent coupling with diazotized sulphanilic acid to yield the monitored dyes with or without a prior separation step by HPLC in a C18 column. The calibration curves obtained are linear in the μg/ml range and r.s.d. values are between 0.5 and 3.7% in all instances. Injection of the sample into the FI manifold allows the total pesticide content in the sample to be screened. The manifold thus acts as a post-column reactor/detector of the chromatograph for samples with high overall carbamate content, which are also injected into the HPLC instrument. The performance was checked with contaminated water samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262326
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Integrated FIA/HPLC method for preconcentration and determination of transition metal ions (1992)
    Springer
    Chromatographia 34 (1992), S. 445-449 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flow injection analysis ; Combined methods ; Transition metal ions ; Aqueous samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An automatic method based on the combination of a flow injection (FI) manifold with a liquid chromatograph has been developed for the enrichment and determination of transition metal ions in water samples. Alternatively, the FI configuration can be used as a screening system for the determination of the total concentration of heavy metals. Two-parameter expressions for calibration graphs involving preconcentration time and concentration of the analytes were established for both the FIA and the integrated FIA/HPLC methods. The preconcentration time depends on the concentration level of the analytes in the samples. The method is linear in the range 2–200 ng/ml, with r.s.d. values between 1.5 and 5.0. It has been applied to the determination of copper, lead, zinc, nickel, cobalt, cadmium and manganese in synthetic water samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290233
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Aminopropyl-silica as an advantageous alternative to nonpolar sorbents for continuous cleanup/preconcentration of vitamin D3 metabolites (1998)
    Springer
    Chromatographia 47 (1998), S. 367-372 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Aminopropyl-silica sorbent ; Continuous cleanup/preconcentration ; Hydroxyvitamin D3 metabolites ; Flow injection analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new procedure for continuous cleanup and concentration of hydroxyvitamin D3 metabolites prior to their separation by HPLC and UV-detection is reported. The process is based on the use of aminopropyl-silica as solid-phase sorbent as an alternative to the use of nonpolar sorbents. The improvement thus achieved has been tested by comparing the results with those obtained using octadecyl-C18 as non-polar sorbent. The comparison has been based on the calibration graphs (linear range, detection and quantitation limits), precision and multiple standard addition method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466466
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    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Supercritical fluid extraction of carbamate pesticides from soils and cereals (1996)
    Springer
    Chromatographia 42 (1996), S. 206-212 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Supercritical fluid extraction ; Carbamate pesticides ; Soils ; Cereal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the supercritical fluid extraction of carbamate pesticides (propoxur, aminocarb, carbaryl and methiocarb) from soil and cereal samples using CO2 is proposed. Extractions were at 378 bar and 54 °C. Analytes were determined in the extracts by HPLC with fluorescence detection after post-column derivatization. Recoveries from spiked soil ranged between 39.6 and 91.7%, depending on analyte and soil components. Lowest recoveries were from sandy soils. Aminocarb could not be recovered from any soil using CO2. Recovery of aminocarb from diatomaceous earth was improved by adding methanol to the extraction cell prior to SFE, but the effect was not observed in soil samples. Recoveries for propoxur and aminocarb from spiked wheat were about 75%, and only between 30–50% for aminocarb from corn and oats, and carbaryl from wheat. Fat was coextracted using CO2 and retained in the trap together with the analytes, however, appropriate rinsing solvent allowed on-line clean-up of the extract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269654
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    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Improved supercritical fluid extraction of sulphonamides (1995)
    Springer
    Chromatographia 40 (1995), S. 197-203 
    Details
    ISSN: 1612-1112
    Keywords: Supercritical fluid extraction ; Sulphonamides ; Modifiers ; In-situ derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Different ways used for enhancing the yield of sulphonamides leached from solid supports are reported. Supercritical CO2 and methanol-modified CO2 were used as extractants of the target analytes and the impregnation of the solid sample with buffer, derivatization of the analytes and ion-pair formation were assessed. Only the sulphonamide/tetramethyl-ammonium ion-pairs are quantitatively extracted from the solid supports using pure supercritical CO2, while the other modifications and the presence of a cosolvent lead to recoveries lower than 30% for most of the analytes. Individual separation/quantitation of the analytes was performed off-line using a liquid chromatograph.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272171
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    Paper (German National Licenses)
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