On-line Concentration Of Phenoxyacid Herbicides By Capillary Electrophoresis

Capillary electrophoresis is a class of liquid-phase microextration ascapillary for the separation channel, as high-voilage for driving force. Amajor drawback of CE is the low-sensitivity. In a variety of methods toimprove CE detection sensitivity, on-line concentration is a simple, conve-nient and effective means. The article which is from the beginning ofincreasing sample-injection and compressing sample zone conducts twoon-line concentration deeply, as to broaden the range of applications ofchrial capillary electrophoresis. Details are as follows:1. An on-line concentration method based on sweeping isconducted on the three pairs of the chrial phenoxy acid herbicides（2,4-drops of propionic acid,2-（3,4,5–trichlorophenoxya-cetic acid）propionic acid and2-（3-chlorophenoxy） propionic acid）, and investigatedthe influence of injection time on the enrichment effect. Under the bestconditions, as to conventional pressure injection, this approach can allowthe detection sensitivity of chiral phenoxy acid herbicides enantiomersincreasing by4900-11000times.2. A dual and sequential electrostacking method based on ASEI-Sweeping was developed for on-line concentration of chiral phenoxy acidherbicides. The effect of high conductivity zone, water plug and injection time was investigated. Under the best conditions, as to conventionalpressure injection, this approach can allow the detection sensitivity ofchiral phenoxy acid herbicides enantiomers increasing by2.2-5.7×10^-5times.The two on-line concentration can increase the detection sensitivityabout3-5order of magnitudes of the phenoxy acid herbicides. Amongthem, especially the ASEI-sweeping achieves the best enrichment effect.In this thesis, two on-line concentrations we studied are applied to thechrial capillary electrophoresis successfully.