The presence of glyphosate residues in our environment and possibilities for their analytical determination

Tuesday, September 30, 2014

1. Summary

When, in 1974, agricultural producers first learned about the then brand new herbicide glyphosate, promising great benefits, who would have thought that in close to forty years the molecular biology industry would be producing plants that will prolong for the unforeseeable future the triumphant march of an active ingredient that seemed to become obsolete? Glyphosate – N-(phosphonomethyl)glycine – was patented by the American company Monsanto as a future herbicide in 1971. The product containing the compound was given the trade name „Roundup”. It acts by entering plant leaves and inhibiting the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), preventing the the synthesis of amino acids containing aromatic rings (phenylalanine, tyrosine, tryptophan). Thus, within a few days after the absorption of the spray, the plant dies. Glyphosate can also be applied in vegetable gardens against agressively spreading couch grass, however, in our own experience, if slightly overdosed, as a total herbicide, it can wipe out the cultivated plants of the garden as well.

 

In the late 1980s, a new chapter has begun in the agrotechnical application of the results of research in molecular biology. The first genetically modified plants produced outdoors appeared. Among these was Roundup Ready Soybean (RR soybean) resistant to glyphosate, probably the „product” of greatest significance. The patent for RR soybean is also owned by Monsanto.

 

The increasing rate of use of glyphosate and the fact that, according to a European survey, the presence of the compound was detected in the urine of 182 people at a frequency of 44%, encouraged us to set up a method in the laboratories of WESSLING Hungary Kft. for the determination of glyphosate residues in foods of vegetable and animal origin, and agricultural products. LC-MS-MS technique was used for the measurements with an electrospray ion source and negative ionization. Identification of the compound in the LC-MS-MS system was performed by monitoring the 16863, 16879 and 168150 transitions. The method developed was validated by the analysis of sample extracts obtained from apples and cow’s milk. In addition, an on-going validation has also been performed using the analytical performance characteristics obtained while analyzing other matrices received by the laboratory. With our method, an average recovery of R=79.4% and a relative standard deviation of RSD=12.6% was achieved at the 10 and 100 μg/kg levels. Thus, repeatability and accuracy of our method were deemed satisfactory.

 

We hope that we can contribute to the imporvement of food and environmental safety of Hungary with the  laboratory analysis of the residues of this herbicide molecule.

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Anton Paar