Influence of soil properties on the enantioselective dissipation of the herbicide lactofen in soils

J Agric Food Chem. 2009 Jul 8;57(13):5865-71. doi: 10.1021/jf9006856.

Abstract

A scheme was developed to elucidate the dissipation behaviors of the two enantiomers of the herbicide lactofen in soils using a normal-phase high-performance liquid chromatograph (HPLC) with UV detector and a column with a cellulose-tri-(3,5-dimethylphenylcarbamate)-based chiral stationary phase (CDMPC-CSP). Eight soils with a wide range of soil properties were studied. Racemic and the enantiopure (S)-(+)- and (R)-(-)-lactofen were incubated under aerobic and anaerobic conditions. The data from sterilized controls indicated that the dissipation of lactofen was biological. The dissipation was shown to be enantioselective with (S)-(+)-enantiomer being degraded faster than the (R)-(-)-enantiomer, resulting in residues enriched with (R)-(-)-lactofen when the racemic compound was incubated. Lactofen was configurationally stable in soil, showing no interconversion of (S)-(+)- to (R)-(-)- enantiomer and vice versa. Significant correlations of the enantioselectivity, expressed as ES = (k((S)) - k((R)))/(k((S)) + k((R))) of lactofen with soil pH were observed under aerobic and anaerobic conditions. In addition, we found that the enantioselectivity correlated with the soil texture rather than the organic carbon.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aerobiosis
  • Anaerobiosis
  • Drug Stability
  • Halogenated Diphenyl Ethers / chemistry*
  • Halogenated Diphenyl Ethers / metabolism
  • Herbicides / chemistry*
  • Hydrogen-Ion Concentration
  • Soil / analysis*
  • Soil Microbiology
  • Stereoisomerism

Substances

  • Halogenated Diphenyl Ethers
  • Herbicides
  • Soil
  • lactofen