Usefulness of micellar media for the quantitative analysis of phenylurea herbicides in water by photochemically-induced fluorescence

UV irradiation of four non-fluorescent phenylurea herbicides including linuron, diuron, isoproturon and neburon is shown to yield fluorescent photoproducts. The photochemically-induced fluorescence (PIF) properties of these herbicides in several media (water, 2-propanol and their mixtures) and aqueous micellar solutions of sodium dodecyl sulfate (SDS), and cetyltrimethylammonium chloride (CTAC) are reported. The use of micellar media enhances significantly the PIF signal relative to an aqueous solution. A PIF method is developed for the determination of the four herbicides under study, with linear dynamic ranges over about one order of magnitude, and limits of detection (LOD) between 410 and 640 ng mL-1, according to the compound. Applications to the analysis of tap water and river water samples yield satisfactory recoveries (86-115 %).