Glyphosate is a common broad-spectrum systemic herbicide used widely to kill weeds especially annual broadleaf weeds and grasses known to compete with crops. There is an interest in the reliable and sensitive quantitation and identification of glyphosate residues, its metabolite AMPA, and the related glufosinate in food and water. Commonly large volume injection into ion chromatography or LC systems based on HILIC followed by sensitivity MS/MS detection is used for analysis. However, interference can influence results in complex samples since the method does not use any cleanup. Derivatization techniques can be used successfully. The method presented here uses derivatization with FMOC-Cl followed by automated SPE cleanup using a Gerstel front-end and detection using LC-MS/MS with an AB SCIEX QTRAP 4500 system. Limits of quantitation in food were found below the target 100 �g/kg allowing dilution to minimize potential ion suppression. In drinking water samples glyphosate was quantified below 0.1 �g/L. Linearity of over three orders of magnitude with r > 0.999 was observed with excellent reproducibility because of the complete automation of the sample handling procedure.

Determination of glyphosate and other polar pesticides using automated FMOC derivatization, SPE cleanup, and LC-MS/MS

248th National Meeting (2014)

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