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  • 1
    Electronic Resource
    Electronic Resource
    An internal surface reversed phase column for the effective removal of humic acid interferences in the trace analysis of mecoprop in soils with coupled-column RPLC-UV (1999)
    Springer
    Fresenius' journal of analytical chemistry 363 (1999), S. 77-82 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In the development of a screening method for the determination of residues of mecoprop in soils involving coupled-column RPLC-UV (228 nm) the cleanup performance of a 5 μm GFF-II internal surface reversed phase (ISRP, Pinkerton) analytical column (50 × 4.6 mm I.D.) as a first column was investigated. In comparison to an analytical C18 column the ISRP column substantially improved the separation between acidic analyte and co-extracted humic substances. Under the selected coupled-column conditions soil extracts obtained after hydrolysis with an aqueous alkaline solution, acidifying and centrifugation could be analyzed directly allowing the determination of mecoprop in soils to a level of about 0.02 mg/kg. A rapid concentration step on a 100 mg C18 solid phase extraction (SPE) cartridge was adopted into the procedure providing a limit of detection (S/N = 3) of 0.01 mg/kg of mecoprop in soil. The method was validated by analyzing freshly spiked soil samples and samples with aged residues. In case of freshly spiked samples the overall recovery was 87% (n = 18, spiked level 0.02–8.0 mg/kg) with a repeatability of 6.8% and a reproducibility of 8.3%. No significant decrease of the recovery was observed for samples with aged residues (n = 15, spiked level 0.1 and 8.0 mg/kg) during a storage of 29 days in the refrigerator at about 4 °C; a storage of 67 days provided a mean recovery of 76% (n = 14, spiked level 8.0 mg/kg).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051141
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of organic matter content in the trace analysis of triazines in various types of soils with GC-NPD (1998)
    Springer
    Chromatographia 48 (1998), S. 450-456 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Soil samples ; Microwave-assisted solvent extraction ; Nitrogen detection ; Triazine herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Recent work demonstrated that the combination of microwave assisted solvent extraction (MASE) and capillary gas chromatography with selective nitrogen detection (GC-NPD) is a viable approach for the efficient determination of triazine herbicides in soils. However, for soils with a high organic matter content or the injection of more concentrated extracts to obtain lower LOD's the performance of gas chromatographic analysis of uncleaned extracts is hampered. This results in both a decrease of the chromatographic response of analytes and a decrease in the life time of the column due to coextracted matrix substances. The effect of various types of soils on the chromatographic analysis of triazine herbicides was studied. It appeared that for the investigated samples with an organic matter content below 5% processing of uncleaned extracts is possible. Samples with a higher organic matter content required a cleanup step. A rapid procedure on 100 mg silica cartridges has been developed using solvents compatible with the MASE extracts and the instrumental analysis. Beside the testing with different standard soils, about 120 samples of an ongoing monitoring program involving three different types of soil (organic matter content: 3–37%) were analysed. The selected compounds atrazine, desethylatrazine, desisopropyl-atrazine and simazine could be assayed in the various soil types to a level of at least 2 μg kg−1. For soil samples with a high organic matter content (〉5%), the rapid cleanup procedure allowed the trace analysis of the triazines and considerably increased the life time of the capillary column. Recoveries at levels from 2 to 50 μg kg−1 ranged from 70 to 100% with RSDs ranging from 5.1 to 9.5%. Confirmation of positive samples was carried out by gas chromatography mass spectrometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467719
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  • 3
    Electronic Resource
    Electronic Resource
    Microwave assisted solvent extraction (MASE) for the efficient determination of triazines in soil samples with aged residues (1996)
    Springer
    Chromatographia 43 (1996), S. 527-532 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Microwave-assistend solvent extraction (MASE) ; Pesticide residue analysis ; Triazine herbicides ; Soil samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of microwave-assisted solvent extraction (MASE) as an alternative for conventional solvent extraction procedures for the determination of some triazine herbicides in soil samples has been investigated. In this study MASE method development was focused on the selection of a suitable extraction solvent prior to the instrumental analysis of uncleaned extracts with gas chromatography and nitrogen-specific detection. A mixture of dichloromethane-methanol (90∶10, v/v) yielded recoveries ranging from 89 to 103 (spiked level 200 μg/kg) with RSDs ranging from 2.1 to 5.3%. This solvent mixture is also very convenient for further procedure. The selected MASE procedure was tested by analyzing freshly spiked soil samples and samples with aged residues of atrazine, desethylatrazine, desisopropylatrazine and simazine. The results were compared with those obtained by a conventional liquid extraction method. The comparative study indicated that MASE yields recoveries at least as good as those obtained by the conventional method. Moreover, the MASE procedure provides low solvent consumption in combination with a high sample throughput.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02293005
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  • 4
    Electronic Resource
    Electronic Resource
    Development of a multiresidue method for nitrogen-containing pesticides (1991)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 339 (1991), S. 357-364 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A great number of commonly used pesticides contain nitrogen and many of these compounds are amendable to gas chromatography with nitrogen-specific detection. Nitrogen-containing pesticides have however poorly been investigated in comparison to the halogen- or phosphorus-containing pesticides as regarded their possible combination in, preferably, a Multiresidue Method (MRM). In the study presented here, a start is made for a systematic approach to the multiresidue analysis of nitrogen-containing pesticides in foodstuffs. An inventory has been made of the target group of compounds and the gaschromatographic behaviour of approx. 20 nitrogen-containing fungicides has been studied, as well as their behaviour in some commonly used extraction and clean-up procedures. Results for the determination of 15 fungicides in cucumber analysed by a modification of MRM 7 of the dutch manual are described. In the near future the method will be extended for the application to other matrices and to approximately 40 nitrogen-containing herbicides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00322348
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