alpha-AMINO-3-HYDROXY-5-METHYL-4-ISOXAZOLEPROPIONIC ACID → alpha-AMINO-3-HYDROXY-5-METHYL-4-ISOXAZOLEPROPIONIC ACID

Participants

Reaction Steps

Glyphosate and/or AMPA stable isotope standards used as internal standards were added to extracts prior to ion exchange SPE purification. Final extracts were prepared in aqueous 0.02M phosphoric acid and filtered (0.2 μm) prior to LC/MS/MS analysis to remove particulates as preventive maintenance measure for the HPLC system. Phosphoric acid acts a weak ion-pairing agent on HPLC polymeric stationery phase and was used as the final solution to improve glyphosate LC/MS/MS performance (response and linearity). The analytes were resolved by HPLC reverse-phase chromatography using a phenyl-hexyl column coupled to electrospray ionization in with MS/MS detection to acquire 2 molecular ion transitions (only 1 ion transition is monitored for AMPA in positive ion mode). Quantitative analysis was accomplished using a single molecular ion transition. The relative abundance of the 2 MS/MS fragment ions provided confirmatory evidence for glyphosate, N-acetylglyphosate, N-acetyl AMPA, and AMPA (negative mode).

Provenance & Evidence