|Polar pesticide analysis by CESI-MS
|Dr Stephen Lock
|Dr Whitney Smith
Abstract Information :
Glyphosate is a common broad-spectrum systemic herbicide used widely to kill weeds especially annual broadleaf weeds and grasses known to compete with crops. Usually native glyphosate is analyzed after derivatization with Fluorenylmethyloxycarbonyl chloride (FMOC-Cl). This derivatization step complicates the analysis and there is a growing need for a method which can detect not only glyphosate but also its major metabolites, for example glufosinate, in their underivitised state.
Standard HPLC methods which have been used to analyze underivitized polar pesticides usually involve HILIC or Hypercarb based separations and are still prone to some technical challenges. In the case of Hypercarb based methods new HPLC columns require conditioning before analysis and other HILIC based methods can be subject to the effects of matrix interferences which can cause retention time drifts and analyte suppression.
Capillary electrophoresis (CE) is a separation technique designed to separate polar constituents based on their charge and size and is well suited to the separation of small polar contaminants such as Glyphosate and its metabolite AMPA. CE takes advantage of extremely low flow rates and although loading amounts are lower than LC based methods this is off set by the huge gains in ion generation and reduction in ion suppression seen at these low flows.
In this presentation we will show how capillary electrospray ionization (CESI-MS) has been used to analyze underivitised polar pesticides such as Glyphosate, AMPA and glufosinate, in fruit juice. This new technique can still achieve low limits of detection as well as separation of a selection of polar pesticides.