One- and two-dimensional direct chiral liquid chromatographic determination of mixtures of diclofop-Acid and diclofop-methyl herbicides

J Agric Food Chem. 2008 Apr 9;56(7):2303-9. doi: 10.1021/jf073519o. Epub 2008 Mar 14.

Abstract

Simple one- and two-dimensional high-performance liquid chromatography (HPLC) methods for the simultaneous enantiomeric determination of alkyloxyphenoxypropionic acid herbicides is presented. Compounds studied were ( R, S)-2-[4-(2,4-dichlorophenoxy)phenoxy]propionic acid (diclofop-acid) and ( R, S)-2-[4-(2,4-dichlorophenoxy)]methyl propionate (diclofop-methyl). Mobile phases necessary to separate their enantiomers on an alpha1-acid glycoprotein chiral stationary phase are different; therefore, the simultaneous separation by an isocratic mode is not possible. The chiral separation method proposed involves a one-step gradient allowing for the simultaneous determination of both racemic enantiomers. Detection limits of the method were 0.03 mg/L for both diclofop-acid enantiomers and 0.14 and 0.15 mg/L for diclofop-methyl enantiomers, respectively. The two-dimensional method involves the use of two chromatographs in one achiral-chiral coupling. The LC-LC method is more suitable for complex samples because it involves an online cleanup effect. Detection limits were 1.25 and 1.87 mg/L for diclofop-acid and 2.70 and 3.02 mg/L for diclofop-methyl enantiomers, respectively. Accuracy, repeatability, and reproducibility have been studied in standard samples and a technical product.

MeSH terms

  • Catechols
  • Chromatography, High Pressure Liquid / methods*
  • Halogenated Diphenyl Ethers
  • Herbicides / analysis*
  • Phenyl Ethers / analysis*
  • Propionates / analysis*
  • Quality Control
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Stereoisomerism

Substances

  • 2,4-dichlorophenoxypropionic acid
  • 2-(4-(2,4-dichlorophenoxy)phenoxy)propionic acid
  • Catechols
  • Halogenated Diphenyl Ethers
  • Herbicides
  • Phenyl Ethers
  • Propionates
  • dichlorfop-methyl