In the present paper we studied the recoveries of glyphosate, N-(phosphonomethyl)glycine (GLY) and its major metabolite, (aminomethyl)phosphonic acid (AMPA) in soil using national (Brazilian) ion-exchange resins, derivatization by a mixture of trifluoroacetic anhydride and trifluoroethanol and analyses by GC-MS. The quantification limits were 12 ng.g-1 for both compounds and the methodology showed a range of recuperation from 85 to 94% with coefficients of variation (CV) ranging from 4.07 to 6.91% for GLY. For AMPA, the mean recoveries ranged from 87 to 102% with CVs ranging from 5.81 to 6.99%. Additional studies showed that, due to the instability of the derivatized compounds, they must be analysed keeping constant time between derivatization and analysis, preferably less than 24 h.
glyphosate; AMPA; GC/MS
