Photodegradation of the herbicide imazethapyr in aqueous solution: Effects of wavelength, pH, and natural organic matter (NOM) and analysis of photoproducts

Ryan Espy, Emily Pelton, Annie Opseth, Jonathan Kasprisin, Amanda M. Nienow

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

The photodegradation of imazethapyr, 5-ethyl-2-(4-isopropyl-4-methyl-5-oxo- 4,5-dihydroimidazol-1H-3-yl)nicotinic acid, has been investigated in phosphate buffers and in buffered solutions containing natural organic matter (NOM). Imazethapyr degrades most quickly under 253.7 nm light and at pH values >4. The presence of NOM in solution caused the reaction rate constants for the photodegradation to decrease, with higher concentrations of NOM having a larger effect. Calculations suggest light screening is the major effect of the NOM. Seven photoproducts have been identified, and a photodegradation mechanism is proposed.

Original languageEnglish (US)
Pages (from-to)7277-7285
Number of pages9
JournalJournal of agricultural and food chemistry
Volume59
Issue number13
DOIs
StatePublished - Jul 13 2011

Bibliographical note

Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.

Keywords

  • imazethapyr
  • imidazolinone
  • natural organic matter
  • photodegradation
  • photolysis
  • photoproducts

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