Submitted to: International Association of Environmental and Analytical Chemistry
Publication Type: Abstract Only
Publication Acceptance Date: June 15, 1997
Publication Date: N/A
Technical Abstract: Supercritical fluid extraction (SFE) is increasingly being used to extract pesticides from a variety of matrices including soils. While SFE has numerous potential advantages over solvent extraction techniques, it does not appear that it will be the universal technique hoped for, particularly in the case of the newer classes of pesticides and aged soil residues. For instance, a general technique could not be developed for sulfonylurea herbicides. Quantitative extraction of metsulfuron methyl and sulfometuron methyl was obtained from different soils using high density methanol- modified CO2, however nicosulfuron could not be extracted. Imidacloprid, an insecticide, was too polar for an efficient extraction from soil; it took a 60-minute extraction with high density methanol-modified CO2 to extract freshly spiked soil. Extraction of aged atrazine and alachlor in soil by SFE was not as efficient as organic solvent extraction and SFE efficiency decreased with atrazine and alachlor aging time in the field. Also, while it has been shown in some cases that addition of modifiers, such as methanol, to make the SF-CO2 more polar, increases extraction of polar pesticides, addition of methanol can also decrease pesticide recovery after extraction due to poor trapping efficiency by solid phase or solvent traps.