title: Improved extraction of atrazine and metolachlor in field soil samples.
abstract: A method was developed for extraction of weathered residues of atrazine and metolachlor from field soils; soils had last been treated with commercial formulations of the herbicides 8-15 months prior to sample collection. Maximum yields were obtained by batch extraction at 75 degrees C for 2-16 h with methanol-water (80 + 20) in a sealed vial. Hydrolysis or other decomposition reactions were minor or negligible, depending on the extraction time. This method is an improvement over published methods that are validated by spike recoveries; the proposed method gives 1.7-1.8 times higher yields compared to shaking for 2 h at room temperature, and 1.3-1.8 times higher yields compared to Soxhiet extraction. The reproducibility of the method was better than 12%. The results underscore the impact of nonequilibrium sorption of organic compounds on analytical methodology and emphasize the need to validate extraction methods with field samples.
authors.affiliation: Connecticut Agricultural Experiment Station, New Haven 06504.
authors.forename: L Q
authors.initials: LQ
authors.lastname: Huang
authors.forename: J J
authors.initials: JJ
authors.lastname: Pignatello
mesh_terms: D000081:Acetamides / Q000032:analysis / Q000302:isolation & purification*; D001280:Atrazine / Q000032:analysis / Q000302:isolation & purification*; D008401:Gas Chromatography-Mass Spectrometry; D006540:Herbicides / Q000032:analysis / Q000302:isolation & purification*; D007202:Indicators and Reagents; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
chemical_list: D000081:Acetamides; D006540:Herbicides; D007202:Indicators and Reagents; D012987:Soil; D012989:Soil Pollutants; D001280:Atrazine; C051786:metolachlor