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  • 1
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Packed columns ; Aqueous samples ; On-line extraction ; Pesticides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Nearly 100 pesticides were eluted with good peak shapes from silica columns using methanol/carbon dioxide mobile phases. The pesticides included organophosphorus, organochlorine, phenylurea, sulfonylurea, triazine, carbamate and phenoxyacid pesticides, demonstrating the wide applicability of SFC to pesticide analysis. A subset of 31 pesticides were on-line extracted from large water samples, typically 10 to 20 ml, but up to 100 ml. The extracts were separated on a 1.6 meter long column packed with 5 μm particles, then detected simultaneously with a photodiode array UV detector plus an electron capture (ECD) and a nitrogen-phosphorus (NPD) detector. Recovery, reproducibility, linearity, response factors and detection limits were determined. Detection limits from a 5 ml water sample were in the range of 100 to 500 parts per trillion (1/1012). Larger samples appear capable of lowering these limits to below 10 ppt.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 30 (1990), S. 57-60 
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography, (SFC) ; Packed columns ; Density gradients ; Effect on efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The efficiency of packed columns was measured as a function of flow rate, temperature, outlet density, and the density differential across the column, unsing pure carbon dioxide as the mobile phase. Although density differentials are often blamed for a serious loss in efficiency in packed column supercritical fluid chromatography, the results show that efficiency was not a function of the density differential. Peak shapes suggest that apparent loss in efficiency is actually due to inadequate solubility of the solute in carbon dioxide.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography, SFC ; Packed columns ; Sulfonylurea ; Pesticide metabolites ; Selective detectors ; Water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Five sulfonylurea herbicides were separated by SFC on both a 25 cm and a 1.6 meter packed column. The former produced rapid analysis, the latter allowed high resolution of a complex mixture containing the solutes of interest. The solutes were simultaneously detected with UV, nitrogen-phosphorus (NPD), and electron capture (ECD) detectors. Peaks of breakdown products of sulfonylureas were characterized by their UV spectra and the presence or absence of nitrogen and chlorine from their NPD and ECD response. Both parent and breakdown products of sulfonylureas were on-line extracted from large water samples with detection limits as low as 50 parts per trillion.
    Type of Medium: Electronic Resource
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