USGS-NWQL: O-2136-01: Glyphosate, Aminomethylphosphonic Acid, and Glufosinate in Water by Liquid Chromatography/Mass Spectrometry
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Official Method Name
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Methods of Analysis by the USGS OGRL - Determination of Glyphosate, Aminomethylphosphonic Acid, and Glufosinate in Water Using Online Solid-Phase Extraction and High-Performance Liquid Chromatography/Mass Spectrometry |
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Current Revision
| 2001 |
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Media
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WATER |
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Instrumentation
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High Performance Liquid Chromatography with Mass Spectrometry |
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Method Subcategory
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Organic |
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Method Source
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Citation
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Lee, E.A., Strahan, A.P., and Thurman, E.M., Methods of Analysis by the U.S. Geological Survey Organic Geochemistry Research Group -- Determination of Glyphosate, Aminomethylphophonic Acid, and Glufosinate in Water Using Online Solid-Phase Extraction and High-Performance Liquid Chromatography/Mass Spectrometry, U.S.Geological Survey Open-File Report 01-454, 17 p. |
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Brief Method Summary
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Samples and spiked samples are amended with internal standards in 19-mL, screw-capped plastic tubes. They are buffered to pH 9.0 by adding borate buffer, and after mixing, a solution of FMOC is added to all tubes. Derivatization is carried out in the dark in a water bath at 40oC. After 24 hours, the reaction is stopped and stabilized by adding 2% phosphoric acid. All tubes are stored in the dark until analyzed. A 5.5-mL aliquot of each sample and the matching standard-addition sample are diluted 1:1 with reagent water in autosampler vials, capped, and placed in the tray of the autosampler. The autosampler provides the sample loading for the automated, online SPE system. 10 mL of the diluted sample are loaded onto the cartridge. After a 500-uL reagent-water rinse, the cartridge is placed into the flow path of the liquid chromatograph (LC) preceding the column. The conditions and gradient of the mobile phase are set to elute the compounds of interest and leave the excess derivatization reagent on the cartridge. The sample's compounds are separated by the LC column and detected by the mass spectrometer (MS). |
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Scope and Application
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The method is suitable for the determination of low concentrations (in micrograms per liter) of dissolved glyphosate, AMPA, and glufosinate in water samples. |
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Applicable Concentration Range
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0.1 - 2.0 ug/L |
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Interferences
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Sample-collection equipment must be free of tubing, gaskets, and other components made of nonfluorinated plastic material that might leach interfering compounds into water samples or absorb the compounds from the water. |
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Quality Control Requirements
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Primary standard solutions, Intermediate composite standard, Standard-addition solution, Internal-standard solution, Internal-standard-solution time reference. |
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Sample Handling
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Filter through a nominal 0.7-um glass-fiber filter. Filters are preconditioned with about 200 mL of sample prior to filtration of the sample. Collect filtrate into baked 125-mL amber glass bottles with Teflon-lined lids. Chill immediately. |
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Maximum Holding Time
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Ship within 3 days of collection; indefinite hold time after derivatization at the laboratory |
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Relative Cost
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Sample Preparation Methods
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Derivatization (FMOC), online SPE extraction |
