Simplified cleanup and liquid chromatographic ultraviolet determination of linuron and three metabolites in potatoes.

A simple and efficient method is presented for the extraction, cleanup, and liquid chromatographic (LC) determination of linuron and 3 of its metabolites, 3-(3,4-dichlorophenyl)-1-methyl urea (DCPMU), 3-(3,4-dichlorophenyl) urea (DCPU), and 3,4-dichloroaniline (DCA), in potatoes. Samples are extracted with acetone, partitioned into dichloromethane-hexane (1 + 1), and cleaned up using disposable silica cartridges. LC determination is performed using a LiChrosorb NH2 5 microns column, with an isopropanol-isooctane gradient mobile phase and UV detection at 248 nm. Recoveries of linuron and 2 of the metabolites from untreated samples fortified at 0.02-2 micrograms/g ranged from 80 to 102%, while recoveries for the metabolite DCA ranged from 60 to 78%. The detection limit was 0.015 micrograms/g for linuron and each metabolite; the minimum quantitation level was 0.5 micrograms/g. The developed method was applied to potato samples from a field experiment.