RAPID-DETERMINATION OF GLUFOSINATE, GLYPHOSATE AND AMINOMETHYLPHOSPHONIC ACID IN ENVIRONMENTAL WATER SAMPLES USING PRECOLUMN FLUOROGENIC LABELING AND COUPLED-COLUMN LIQUID-CHROMATOGRAPHY

The approach presented in recent work [J.V. Sancho et al., J. Chromato gr. A, 678 (1994) 59] concerning the rapid determination of glufosinat e in environmental water samples was successfully applied to the devel opment of efficient procedures including the assay of glyphosate and i ts main metabolite, aminomethylphosphonic acid (AMPA). The methodology involves two approaches: (i) a multi-residue method allowing the simu ltaneous determination of the three analytes in environmental water sa mples to a level of 1 mu g/l or (ii) single residue methods focused on the analysis of a single analyte to the sub-mu g/l level. The procedu res involve a precolumn derivatisation step with 9-fluorenylmethylchlo roformate (FMOC-Cl) yielding highly fluorescent derivatives of the ana lytes which then can be determined by coupled-column LC with fluoresce nce detection using a reversed-phase C-18 column (C-1) coupled to a we ak ion-exchange column (C-2). The separation power of the first column (C-1) was used to achieve sensitivity, by injecting large volume samp les, and automated sample clean-up was achieved by removing the less p olar interferences, including the excess of hydrolysed reagent (FMOC-O H). Using these procedures, glufosinate, glyphosate and AMPA were succ essfully recovered from water samples at 0.50-10 mu g/l fortification levels, with a sample throughput of at least 40 samples per day.