Analysis of glyphosate and its metabolite, aminomethylphosphonic acid,in agricultural products by HPLC

Abstract

An analytical method for residues of the herbicide glyphosate [GLY: N-(phosphonomethyl)glycine] and its metabolite (AMPA: aminomethylphosphonic acid) in agricultural products is described. GLY and AMPA were extracted with water (soybeans extract was moreover treated with acetone), and purified by application to a dual mini-cartridge column (octadecyl-bonded silica gel and cation-exchange silica gel) system. GLY was derivatized with 9-fluorenylmethylchloroformate, and determined by HPLC with fluorescence detection. AMPA determination was performed by HPLC employing postcolumn fluorogenic labeling with o-phthalaldehyde-mercaptoethanol. The detection limits for GLY and AMPA were 0.04 μg/g (soybean: 0.08 μg/g), and both recoveries from samples to which the compounds were added at the 0.2 μg/g level (soybean: 1.0 μg/g) were more than 65%.