U.S. Geological Survey
Open-File Report 00-385

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Methods of Analysis by the U.S. Geological Survey Organic Geochemistry Research Group-Determination of Selected Herbicides Metabolites and Their Degradation Products in Water Using Solid-Phase Extraction and Gas Chromatography/Mass Spectrometry

Abstract

A method for the extraction and analysis of eight herbicides and five degradation products using solid-phase extraction from natural water samples followed by gas chromatography/mass spectrometry is presented in this report. This method was developed for dimethenamid; flufenacet; fluometuron and its degradation products, demethylfluometuron (DMFM), 3-(trifluromethyl)phenylurea (TFMPU), 3-(trifluromethyl)-aniline (TFMA); molinate; norflurazon and its degradation product, demethylnorflurazon; pendamethalin; the degradation product of prometryn, deisopropylprometryn; propanil; and trifluralin. The eight herbicides are used primarily in the southern United States where cotton, rice, and soybeans are produced. The exceptions are dimethenamid and flufenacet, which are used on corn in the Midwest.

Water samples received by the U.S. Geological Survey's Organic Geochemistry Research Group in Lawrence, Kansas, are filtered to remove suspended particulate matter and then passed through disposable solid-phase extraction columns containing octadecyl-bonded porous silica (C-18) to extract the compounds. The herbicides and their degradation products are removed from the column by ethyl acetate elution. The eluate is evaporated under nitrogen, and components then are separated, identified, and quantitified by injecting an aliquot of the concentrated extract into a high-resolution, fused-silica capillary column of a gas chromatograph/mass spectrometer under selected-ion mode.

Method detection limits ranged from 0.02 to 0.05 Îg/L for all compounds with the exception of TFMPU, which has a method detection limit of 0.32 Îg/L. The mean absolute recovery is 107 percent. This method for the determination of herbicides and their degradation products is valuable for acquiring information about water quality and compound fate and transport in water.

Additional information about the Organic Geochemistry Research Laboratory can be found at: http://ks.water.usgs.gov/studies/reslab/

Kish, J.L., Thurman, E.M., Scribner, E.A. and Zimmerman, L.R.. 2000, Methods of Ananysis by the U.S. Geological Survey Organic Geochemistry Research Group--Determination of Selected Herbicides and Their Degradation Products in Water Using Solid-Phase Extraction and Gas Chromatography/Mass Spectrometry: U.S. Geological Survey Open-File Report 00-385, 13 p.

To request a paper copy of this publication, email: GS-W-KS_info@usgs.gov