Multiresidue analysis of phenylurea herbicides in environmental waters by capillary electrophoresis using electrochemical detection

A rapid multiresidue method has been developed for the analysis of seven phenylurea herbicides in the presence of two s-triazines in environmental waters. A simple end-column electrochemical detector was used in combination with a commercially-available capillary electrophoresis instrument with UV detection. The determination of phenylurea pesticides using micellar electrokinetic capillary chromatography with electrochemical detection represents the first such determination that has been reported. In both detection systems, linear ranges were obtained for the seven phenylurea herbicides at concentrations lower than 2.0×10^–5 mol l^–1, in 0.020 mol l^–1 phosphoric acid at pH 7.0 and containing 0.020 mol l^–1 of sodium dodecylsulfate, in order to obtain selectivity in the additional separation by a micellar distribution process. Under these conditions a detection limit lower than 5.0×10^–6 mol l^–1 (0.25 pmol of pesticide) was achieved for most of them. The pesticides were resolved in less than 30 min.