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A rapid, selective and sensitive gas Chromatographic (GC) method for the simultaneous determination of the phosphorus-containing amino acid-type herbicides glyphosate (GLYP), its metabolite aminomethylphosphonic acid (AMPA) and glufosinate (GLUF) in environmental and food samples was developed. After extraction of the sample with water or sodium hydroxide solution, these compounds were converted into their N-isopropoxycarbonyl methyl ester derivatives and then measured by GC using a DB-1701 capillary column with flame photometric detection (FPD). The derivative preparation and GC analysis were accomplished within 20 min. The derivatives were sufficiently volatile and stable, and the FPD response was excellent. The detection limits of AMPA, GLYP and GLUF, at a signal-to-noise ratio of 3, were ca. 8, 12 and 20 pg injected, respectively. The calibration graphs for these compounds in the range 5–200 ng were linear and sufficiently reproducible for quantitative determination. This method could be successfully applied to river water, soil and carrot samples without a preliminary clean-up procedure, and AMPA, GLYP and GLUF could be measured without any interference from co-existing substances. The recoveries of these compounds in these samples were 91–106%. |
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