ANALYSIS OF CHLOROPHENOXY ACID HERBICIDES BY CYCLODEXTRIN-MODIFIED CAPILLARY ELECTROPHORESIS

In this study, we developed a capillary electrophoresis method involvi ng cyclodextrins to separate seven chlorophenoxy acid herbicides and t heir enantiomers. The cavity size and the concentration of cyclodextri ns heavily influenced the migration time of individual herbicides. The peak resolution also varied with different concentration ratios of cy clodextrins. Adding 4 mM alpha-cyclodextrin and 1 mM beta-cyclodextrin in the buffer was found to produce the optimum experimental condition . The herbicides examined in this study could be successfully separate d within 7 min; meanwhile, the two pairs of enantiomers could also be completely resolved. The calibration lines' correlation coefficients f or the separation conditions were all above 0.996. The dynamic range o f the analysis of seven herbicides was at least two orders, from 1 ppm to 100 ppm. Analyzing the seven herbicides by capillary electrophores is posed the advantages of a high resolution, high separation efficien cy and good reproducibility. By combining with a C-18 disk preconcentr ation method, the herbicides' detection limits in the environmental wa ter were below 1 ppb.