U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of the Technical Meeting Charleston South Carolina March 8-12,1999--Volume 2 of 3--Contamination of Hydrologic Systems and Related Ecosystems, Water-Resources Investigation Report 99-4018B

Determination of Chloroacetanilide Herbicide Metabolites in Water Using High-Performance Liquid Chromatography-Diode Array Detection and High-Performance Liquid Chromatography/Mass Spectrometry

By Kenneth A. Hostetler and E. M. Thurman

This report is available in pdf format: Hostetler.pdf

ABSTRACT

Analytical methods using high-performance liquid chromatography-diode array detection (HPLC-DAD) and high-performance liquid chromatography/mass spectrometry (HPLC/MS) 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 HPLC/MS 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 µg/L (micrograms per liter) ranged from 84 to 112 percent, with relative standard deviations of 18 percent or less. The average HPLC/MS recoveries of the metabolites from water samples spiked at 0.05, 0.2, and 2.0 µg/L ranged from 81 to 118 percent, with relative standard deviations of 20 percent or less. The limit of quantitation (LOQ) for all metabolites using the HPLC-DAD method was 0.20 µg/L, whereas the LOQ using the HPLC/MS method was at 0.05 µg/L. These metabolite-determination methods are valuable for aquiring information about water quality and the fate and transport of the parent chloroacetanilide herbicides in water.