| 17002407 |
Lagarde F, Puetz T, Dressel J, Fuehr F: Simultaneous determination of ethidimuron, methabenzthiazuron, and their two major degradation products in soil. J Agric Food Chem. 2006 Oct 4;54(20):7450-9.
An analytical method has been developed for the quantification of two herbicides (ethidimuron and methabenzthiazuron) and their two main soil derivatives. This method involves fluidized-bed extraction (FBE) prior to cleanup and analysis by reverse-phase liquid chromatography with UV detection at 282 nm. FBE conditions were established to provide efficient extraction without degradation of the four analytes. (14) C-labeled compounds were used for the optimization of extraction and purification steps and for the determination of related efficiencies. Extraction was optimal using a fexIKA extractor operating at 110 degrees C for three cycles (total time = 95 min) with 75 g of soil and 150 mL of a 60:40 v/v acetone/water mixture. Extracts were further purified on a 500 mg silica SPE cartridge. Separation was performed on a C18 Purosphere column (250 mm x 4 mm i.d.), at 0.8 mL min (-1) and 30 degrees C with an elution gradient made up of phosphoric acid aqueous solution (pH 2.2) and acetonitrile. Calibration curves were found to be linear in the 0.5-50 mg L (-1) concentration range. Besides freshly spiked soil samples, method validation included the analysis of samples with aged residues. Recovery values, determined from spiked samples, were close to 100%. Limits of detection ranged between 2 and 3 microg kg (-1) of dry soil and limits of quantification between 8 and 10 microg kg (-1) of dry soil. An attempt to improve these performances by using fluorescence detection following postcolumn derivatization by orthophthalaldehyde-mercaptoethanol reagent was unsuccessful. |
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