Determination of napropamide in technical formulations, soil and vegetable samples by sensitised fluorescence: validation of the method Original Research Article

A fluorimetric method was developed for the determination of napropamide in aqueous micellar solutions of sodium dodecyl sulphate (SDS). The determination was performed at pH 7.2, obtained by a 0.5 M phosphate buffer solution, and 0.08 M SDS. In micellar solutions the fluorescence emission intensity was measured at 337 nm (excitation at 288 nm). The linear calibration ranges for napropamide were 10–100 ng ml−1 and 0.1–2.0 μg ml−1. The detection limit, according to the error propagation theory, was 4.2 ng ml−1. The relative standard deviations (n=10) were 0.88 and 0.78%, respectively, for 60 and 1600 ng ml−1 napropamide. The fluorimetric method was applied to the determination of napropamide in a technical formulation and spiked soil and vegetable samples (pepper and tomato). Dichloromethane was used for the extraction of the herbicide from soil, pepper and tomato samples. Owing to matrix interference, vegetable samples were analysed using a standard addition calibration technique.