Thank you very much Rani P Ramachandran

Nurkhalida Kamal

Glyphosate is currently one of the most common pesticides used worldwide. The analysis of glyphosate is challenging due to its high polarity. A new innovative method based on reverse phase liquid chromatography/tandem mass spectrometry is introduced here. The separation and the pesticides’ quantification is possible due to the in-vial addition of a pairing agent. In this approach, the quantity of pairing agent may be as low as 125 nmol per injection, allowing the protocol to benefit from all the advantages of classical ion-pairing without the disadvantages. 35,000 tons per year – this is the amount of pesticides applied in the European Community, and there are many different types to look for. Pesticides are a large variety of substances, with multiple residues belonging to multiple classes. This makes the analysis a challenging task. It may require either liquid chromatography or SFC tandem mass spectrometry (LC-MS/MS or SFC-MS/MS) or gas chromatography tandem mass spectrometry (GC-MS/MS).  These triple quadrupole mass spectrometers are the most widely used in pesticide screening due to their fast acquisition speed in selected reaction monitoring (SRM) allowing the screening of hundreds of pesticides simultaneously in one run with high sensitivity, selectivity, and a wide linear range. The hazardous level of a pesticide depends on two factors: its toxicity and a person’s exposure to that pesticide. Just a single exposure can have acute effects, such as impaired vision and motor disorders. Long-term, chronic exposure can lead to more serious illnesses and diseases, including blood and nerve disorders and even cancer. Because of these risks, the MRLs (Maximum Residue Limits) have been defined in the European Community for any food or feed where pesticides are applied correctly according to GAP (Good Agricultural Practices) in order to ensure the lowest consumer exposure. Commission Regulation (EC) No. 396/2005 lists 320 defined commodities for which more than 152,000 MRLs have been set. The pesticide maximum residue levels are published by the EU Commission and regularly updated such as Regulation (EU) 2019/90 of 18 January 2019. The focus of this article is the analysis of Glyphosate and Glufosinate which are phytosanitary products widely used as weed killers, especially in cereal and vegetable crops. Glyphosate works by blocking the chain of synthesis of amino acid precursors essential for the functioning of the plant, especially for photosynthesis. In 2015, the World Health Organization published a report concluding that Glyphosate, the most widely used herbicide, should be classified as probably carcinogenic to humans as well as its major metabolite Aminomethylphosphonic acid (AMPA). Analysis of Glyphosate, Glufosinate, and AMPA is difficult and expensive, because of their hydrophilic and ionic characteristics which prevent their analysis in a multi-residue method for monitoring the environment and food. Currently, different analytical techniques are used. Some analysis use derivatisation with active reagent such as FMOC (Fluorenylmethyloxycarbonyl), but this derivatisation step complicates their quantification. That’s why many other approaches such as Anion exchange, Hydrophilic Interaction Liquid Chromatography (HILIC), Hypercarb, and mixed-mode columns to determine underivatised Glyphosate and other polar pesticides with LC-MS/MS in food matrixes have been tried. All these methods have limited success.

Method

The system configuration used for this type of analysis consists of the Shimadzu Nexera X2 liquid chromatograph with LCMS-8060 triple quadrupole mass spectrometer. Multiple Reaction Monitoring (MRM) in negative mode is performed with the transitions 167.9>62.9, 179.9>85.0 for Glyphosate, 110.0>62.9, 179.9>85.0 for AMPA, and 179.9>63.0, 179.9>85.0 for Glufosinate. This setup, following the analytical conditions listed in Table 1 enables the quantification of Glyphosate, Glufosinate, and AMPA with a lower limit of detection below 50 µg/kg for fruits, and below 100 µg/kg for other matrices.

Thank you very much Rani Kashif Ameer for sharing the information.