Determination of glyphosate herbicide and aminomethylphosphonic acid in natural waters by liquid chromatography using pre-column fluorogenic labeling. Part I: Direct determination at the 0.1 $\mu$g/L level using FMOC

An analytical method has been developed for the determination of glyphosate herbicide and its metabolite aminomethylphosphonic acid (AMPA) in natural waters to a level of 0.10 $\mu$g/L with a good linearity in the range 0.10-2.00 $\mu$g/L and coefficients of variation under 20% for each spiked level. The procedure involves a precolumn derivatization step with 9-fluorenylmethylchloroformate (FMOC-Cl) yielding highly fluorescent derivatives of the analytes which then can be determined by HPLC with fluorescence detection. The method is used for analysis of natural (surface and ground) and treated waters. Matrice effects have been pointed out, particularly the effects of hard ionic content and the effects of chlorine residues into treated waters