Effect of pH on the Hydrolytic Transformation of a New Mixture Formulation of Fomesafen and Quizalofop-ethyl in Water

Bull Environ Contam Toxicol. 2020 Apr;104(4):471-476. doi: 10.1007/s00128-020-02808-x. Epub 2020 Feb 23.

Abstract

A hydrolytic transformation study was conducted in water of pH 4.0, 7.0 and 9.2 to evaluate the effect of pH on persistence of a new readymix formulation of fomesafen and quizalofop-ethyl. The water samples were fortified at 0.5 and 1 µg mL-1 levels and analysed at 0 (2 h), 1, 3, 7, 15, 30, 60, 90, 120, 150 days interval. Both the analytical methods were validated following SANTE guideline and found accurate based on average recovery of 80-100%, Relative standard deviation (RSD) < 20% and Coefficient of Determination (R2) 0.99. The dissipation of both the molecules was pH dependent and followed first order kinetics. Higher persistence of fomesafen was observed in alkaline pH as compared to neutral and acidic pH with half-life of 41.56-63.24 days, whereas higher stability of quizalofop-ethyl was observed in the water of acidic pH followed by neutral and alkaline pH with half-life of 1.26-8.09 days.

Keywords: Fomesafen; Half-life; Hydrolysis; Quizalofop-ethyl; Water; pH.

MeSH terms

  • Benzamides / analysis*
  • Fresh Water / chemistry*
  • Herbicides / analysis*
  • Hydrogen-Ion Concentration
  • Hydrolysis
  • Kinetics
  • Models, Theoretical
  • Propionates / analysis*
  • Quinoxalines / analysis*
  • Water Pollutants, Chemical / analysis*

Substances

  • Benzamides
  • Herbicides
  • Propionates
  • Quinoxalines
  • Water Pollutants, Chemical
  • quizalofop-ethyl
  • fomesafen