DETERMINATION OF THE HERBICIDE GLYPHOSATE AND ITS METABOLITE (AMINOMETHYL)PHOSPHONIC ACID BY GAS-CHROMATOGRAPHY WITH FLAME PHOTOMETRIC DETECTION

A rapid, selective and sensitive method was developed for determining glyphosate and (aminomethyl)phosphonic acid (AMPA) by gas chromatography (GC). These compounds were converted into their N-isobutoxycarbonyl methyl ester derivatives and measured by GC with flame photometric detection, using a fused-silica capillary column with a cross-linked DB-1701. The calibration curves for glyphosate and AMPA in the range of 5-200 ng were linear, and the detection limits were about 10 and 15 pg as injection amounts, respectively. This method was applied to water and soil samples without a preliminary clean-up procedure, and glyphosate and AMPA were measured without any influence from coexisting substances. The recoveries of these compounds in potable water and river water samples were 96.2-100.3%, and those in soil samples were 81.7-99.1%.