Study of the enantioseparation of imazaquin and enantioselective degradation in field soils by CZE

A fast, simple, and sensitive CE method was developed to study the separation and degradation of imazaquin enantiomers in field soils. The parameters pH and concentration of the buffer electrolyte, type and concentration of the chiral selectors, applied voltage, and temperature of the CE system were investigated. Sodium hydrogen phosphate (50 mM) at pH 10.1 containing 30 mM hydroxypropyl-beta-CD (HP-beta-CD) was found to be the suitable BGE. The reliable determination for imazaquin enantiomers was obtained at 20 kV applied voltage, 15 degrees C separation system, and detection at 214 nm. Under the optimal conditions, the LODs (S/N = 3) were 0.0097 and 0.0098 mg/kg; linearity ranged from 0.019 to 1.24 and 0.020 to 1.26 mg/kg for the first-eluting peak of imazaquin (imazaquin-I) and the second-eluting peak of imazaquin (imazaquin-II) in soil, respectively. The precision in terms of the percentage of RSD (%RSD) calculated from peak area was not greater than 5%. With the suitable characteristics of the present method, it was applied to the study of enantioselective degradation in field soil. According to the calculated values of the enantiomer ratio (ER) and the rate constant of degradation (k), the results suggested that the degradation rate of the two enantiomers were slightly different, and that the pH of the soil had a strong influence on the rate of degradation.