Determination of chloroacetanilide herbicide metabolites in water using high-performance liquid chromatography-diode array detection and high-performance liquid chromatographyrmass spectrometry

Analytical methods using high-performance liquid chromatography-diode array detection HPLC-DAD. and high-performance liquid chromatographyrmass spectrometry HPLCrMS. were developed for the analysis of the following chloroacetanilide herbicide metabolites in water: alachlor ethanesulfonic acid ESA.; alachlor oxanilic acid; acetochlor ESA; acetochlor oxanilic acid; metolachlor ESA; and metolachlor oxanilic acid. Good precision and accuracy were demonstrated for both the HPLC-DAD and HPLCrMS methods in reagent water, surface water, and ground water. The average HPLC-DAD recoveries of the chloroacetanilide herbicide metabolites from water samples spiked at 0.25, 0.5 and 2.0 mgrl ranged from 84 to 112%, with relative standard deviations of 18% or less. The average HPLCrMS recoveries of the metabolites from water samples spiked at 0.05, 0.2 and 2.0 mgrl ranged from 81 to 118%, with relative standard deviations of 20% or less. The limit of quantitation LOQ. for all metabolites using the HPLC-DAD method was 0.20 mgrl, whereas the LOQ using the HPLCrMS method was at 0.05 mgrl. These metabolite-determination methods are valuable for acquiring information about water quality and the fate and transport of the parent chloroacetanilide herbicides in water.