The safety residual level of glyphosate in food is regulated in the U.S., Europe, and other global regions. Direct analysis of underivatized glyphosate, however, can be challenging due to its minimum retention on a reversed-phase or hydrophilic interaction chromatography (HILIC) column and severe adsorption onto the stainless flow path. On the other hand, glyphosate and other polar anionic contaminants tend to strongly retain on an anion-exchange column and require high salt mobile phase to elute, which is not friendly to mass spectrometric analysis.
These challenges motivated the invention of a hybrid ion-exchange/HILIC column offering balanced retention and separation of ionic and other highly polar compounds. An LC-MS/MS solution was developed for the direct analysis of underivatized glyphosate, aminomethylphosphonic acid (AMPA), and glufosinate, as well as other 14 highly polar contaminants listed in the Quick Polar Pesticides Extraction (QuPPe) method in seven food matrices (rice, baby cereal, soybean, lemon grass, oregano, tea, and strawberry). All 17 compounds were analyzed simultaneously in a single run with a total analysis time of less than 19 minutes. This method was able to chromatographically separate components sharing the same mass fragments, including AMPA/fosetyl aluminum and fosetyl aluminum/phosphonic acid. This approach enabled by unique column selectivity allows for the analysis of multiple polar pesticides in a simple method suitable for routine analysis.
