|Lerch, Robert - Bob|
Submitted to: International Association of Environmental and Analytical Chemistry
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/1999
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Hydroxylated atrazine degradation products (HADPs) are a major class of atrazine metabolites that are persistent in soils and contaminate surface waters throughout the Midwestern United States. Analytical methodology for the recovery of HADPs from soils and sediments has been lacking because their sorption mechanisms were poorly understood. The developed method employs a mixed-mode extractant [3:1 0.5M KH2PO4, pH 7.5:CH3CN (v/v)] designed to disrupt the two primary mechanisms of HADP sorption to soils: cation exchange and hydrophobic interactions. In addition, the mixed-mode extractant is more environmentally friendly then the organic solvents typically used for pesticide extraction since only a small amount of CH3CN waste is generated by this procedure. Strong anion exchange (SAX) solid-phase extraction (SPE) is used for sample clean-up followed by isolation and concentration using strong cation exchange SPE. HADPs were quantitated by LC/MS/MS and LC/UV. For LC/MS/MS analysis, a Perkin-Elmer Sciex API 365 mass spectrometer was used with an ApCI ionization interface utilizing multi-reaction monitoring (MRM). Comparison of HADP quantitation by LC/UV and LC/MS/MS showed generally good agreement, indicating that LC/UV is viable for quantitation using this method. Method recoveries were determined by spiking 14C-HADPs into three soils with lengthy atrazine use histories. Recoveries ranged from 74-81% for 14C-HA, 79-88% for 14C-DEHA, and 64-77% for 14C-DIHA. HADP concentrations for these soils were 66.9-178 #g/kg for HA, 8.99-40.9 #g/kg for DEHA, and 5.27-16.2 #g/kg for DIHA. The quantitation and identification of HADPs are important to testing current theories regarding their persistence in surface soils and the geochemical mechanisms responsible for their presence in stream water.