Determination of 2,4-D and Dicamba in food crops by MEKC

The determination of 2,4-D (2,4-dichlorophenoxyacetic acid) and Dicamba (2- methoxy-3,6-dichlorobenzoic acid) residues in sugar cane, rice and corn was performed by a supercritical fluid extraction (SFE) method using CO2/aceto ne as extraction mix and an SFE apparatus developed in our laboratory. The extracts were cleaned up after extraction by both liquid-liquid partition a nd a Florisil column. Micellar electrokinetic capillary chromatography (MEK C) coupled with ultraviolet on-column detection was used for the analysis o f these pesticides. The detection limits were improved by the preparation o f a special detection cell with an increased pathlength that gave detection limits of ca. 0.6 pg for 2,4-D and Dicamba. Our results demonstrated that capillary electrophoresis can be a powerful new analytical tool for pestici de residue analysis.