SEPARATION OF 6 PHENYLUREAS AND CHLORSULFURON STANDARDS BY MICELLAR, MIXED MICELLAR AND MICROEMULSION ELECTROKINETIC CHROMATOGRAPHY

The usefulness of electrokinetic chromatography (EKC) for the determination of phenylureas and chlorosulfuron herbicides was investigated. Micellar, mixed micellar and microemulsion EKC were examined for this purpose and compared systematically. Micelles formed from sodium dodecyl sulfate (SDS), mixed micelles formed from SDS and polyethylene glycol 400 monolaurate and oil-in-water microemulsions formed from SDS, n-butanol and n-octane were mainly employed. Capacity factors showed that the separation of the herbicides by ECK employing SDS follows an interaction mechanism similar to that in reversed-phase HPLC. Although there was not much difference in the elution order of the herbicides among the three modes of EKC, there were differences in separation selectivity. The separation efficiencies in mixed micellar and microemulsion EKC were higher than that in micellar EKC. Under the same separation conditions, the migration window in mixed micellar EKC was narrower than that in micellar EKC, but the migration window in microemulsion EKC was wider than that in micellar EKC and was also much easier to extend by changing the SDS concentration and applied voltage. The effects of the separation conditions on the separation of the herbicides by micellar EKC and microemulsion EKC were investigated.