engleski

Microwave-Assisted Extraction of Triketone and Pyrazole Corn Herbicides from Agricultural Soil

The benzoylcyclohexanedione (triketone) herbicides mesotrione and tembotrione and benzoylpyrazole herbicide topramezone have recently been released for commercial use in corn production. The objective of this study was to develop and validate a new method for the simultaneous extraction of mesotrione with its two degradation products 4-methylsulfonyl- 2-nitrobenzoic acid (MNBA) and 2-amino-4- methylsulfonyl-benzoic acid (AMBA), tembotrione and topramezone from agricultural soil. Our analytical method is based on microwave- assisted extraction (MAE) followed by reversed- phase liquid chromatography, using gradient elution with acetonitrile and acidified water (pH 2.2) and diode array detection at 205 and 220 nm. MAE operational parameters (solvent type and volume, extraction temperature and time) were optimized with respect to the extraction efficiency of the target compounds from dry soils fortified at 0.2 and 0.1 mg kg- 1. The highest recoveries (70-94 % for herbicides and MNBA and <30 % for AMBA), with satisfactory method precision (RSD ≤20 %), were achieved by extraction of soil with solvent mixture ψ (methanol, 0.1 mol L-1 HCl) = 9:1 at 60 °C for 5 min. The method has proven suitable for residue analysis of target herbicides and MNBA in neutral, low humic silt loam soils, with an analyte detection limit of 0.002 mg kg- 1 of soil dry mass.

herbicides ; mesotrione ; tembotrione ; topramezone ; microwave-assisted extraction ; soil

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