title: Simultaneous determination of ethidimuron, methabenzthiazuron, and their two major degradation products in soil.
abstract: 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.
authors.affiliation: Laboratoire des Sciences Analytiques, UMR 5180 CNRS-UCBL, bât CPE 43, boulevard du 11 novembre 1918, 69622 Villeurbanne cédex, France. florence.lagarde@univ-lyon1.fr
authors.forename: Florence
authors.initials: F
authors.lastname: Lagarde
authors.forename: Thomas
authors.initials: T
authors.lastname: Puetz
authors.forename: Joachim
authors.initials: J
authors.lastname: Dressel
authors.forename: Fritz
authors.initials: F
authors.lastname: Fuehr
mesh_terms: D052160:Benzothiazoles / Q000032:analysis* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006540:Herbicides / Q000032:analysis*; D008782:Methylurea Compounds / Q000032:analysis* / Q000737:chemistry; D010782:Photolysis; D012680:Sensitivity and Specificity; D012987:Soil / Q000032:analysis*; D012996:Solutions
chemical_list: D052160:Benzothiazoles; D006540:Herbicides; D008782:Methylurea Compounds; D012987:Soil; D012996:Solutions; C514786:ethidimuron; C011912:methabenzthiazuron