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United States Department of Agriculture

Agricultural Research Service

Title: A PROPOSED CONVENTION FOR REPRESENTING ACID-BASE BEHAVIOR OF PESTICIDES IN PESTICIDE PROPERTY DATABASES DESIGNED FOR SIMULATION MODELING

Author
item Wauchope, Robert

Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: December 31, 2003
Publication Date: March 20, 2004
Citation: Wauchope, R.D. 2004. A proposed convention for representing acid-base behavior of pesticides in pesticide property databases designed for simulation modeling. American Chemical Society National Meeting, Anaheim, CA, 2004. Picogram 66, Abs #15(2003), AGRO Division, Am. Chem. Soc. Washington, DC.

Technical Abstract: A reported 'pKa' or 'pKb' for a pesticide provides ambiguous information unless the specific way of expressing the equilibrium equation for the reaction is defined. If the dependence of environmental properties of a pesticide on its' ionization state are to be incorporated into a computer-readable database, the fields must also be unambiguous. An example is proposed, using a four-parameter database structure to describe any pesticide's soil organic matter sorption coefficient as a function of soil pH. The parameters can be unambiguously interpreted by a computer without additional input, whether the pesticide is acidic or basic or multifunctional. The four parameters are surface acidity ', pesticide pKa, and organic matter sorption coefficients for the two molecular species Pq-1 and Pq, the reactant and product in the equilibrium expression. This approach will be demonstrated for acidic and basic pesticides.

Last Modified: 9/1/2014
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