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Gas chromatography‐mass spectrometry analysis of the herbicide clopyralid in differentially cultivated soils
Author(s) -
Schütz Stefan,
Weißbecker Bernhard,
Hummel Hans E.
Publication year - 1996
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620150304
Subject(s) - clopyralid , chemistry , soil water , solid phase extraction , mass spectrometry , derivatization , gas chromatography , gas chromatography–mass spectrometry , extraction (chemistry) , chromatography , environmental chemistry , leaching (pedology) , environmental science , agronomy , weed control , soil science , biology
The herbicide clopyralid offers a high selectivity in thistle control using low application rates. Contradictory results in soil leaching experiments using this herbicide indicate the need for a reliable procedure for trace analysis of clopyralid. The problem of poor extraction efficiency from soil that is rich in humic substances was solved by ultrasound‐enhanced alkaline extraction. Analysis of the extract was performed by gas chromatography‐mass spectrometry after derivatization with pentafluorobenzylbromide in an ultrasound‐enhanced phase‐transfer catalytic reaction. Tetrabutylammoniumbromide served as a phase‐transfer catalyst. For improving analytical reliability, 2,5‐dichlorobenzoic acid was used as an internal standard. The achieved detection (1 μg/kg = 1 ppb) and quantification (10 μg/kg) limits of clopyralid in soil were appropriate for determining the degradation behavior in herbicide‐treated soils. The half‐life of clopyralid in two differentially cultivated soils was determined in laboratory trials. Uncultivated soil that was rich in humic acids showed a higher half‐life than cultivated soil.