Analysing  Maximum Residue Levels (MRLs) for pesticides

Pesticides are commonly used in the production of fruits and vegetables to prevent pest infestation and improve the shelf-life of fresh produce. However, the use of pesticides raises concerns about potential health risks to consumers through the presence of residue on the food we eat. To mitigate these concerns, regulatory bodies set Maximum Residue Levels (MRLs) for pesticides, which specify the highest level of a pesticide that is considered safe to be present in a given crop.

In the European Union, if a pesticide is not explicitly mentioned in the MRL legislation, a default MRL is used for enforcement. This default value is set to be equal to the limit of quantification (LOQ) achievable with the analytical methods used for analysis. National authorities control and enforce MRLs by testing samples for pesticide residue levels using analytical surveillance programs. These programs check for compliance with MRLs, assess dietary exposure, and check for the use of unauthorised pesticides. The food industry also carries out its own due diligence analyses to ensure compliance with MRLs.

To effectively analyse for pesticide residues, mass spectrometry (MS) coupled with both gas chromatography (GC) and liquid chromatography (LC) is needed to provide comprehensive analysis with sufficient sensitivity to meet global MRL regulations. The use of Quick, Easy, Cheap, Efficient, Rugged and Safe (QuEChERS) sample extraction and clean up has streamlined analytical efficiencies for multi-residue analyses. Additionally, the use of ultra high performance liquid chromatography (UHPLC) coupled with tandem quadrupole mass spectrometry (MS/MS) for multi-residue pesticide analysis is widely reported. More recently, the use of GC-MS/MS utilising atmospheric pressure ionisation (APGC) has been shown to offer significant improvements in performance over Electron Impact (EI) for challenging pesticides in terms of selectivity, specificity, and speed of analysis.

It is important to note that while MRLs are in place to ensure the safety of our food supply, it is still important for consumers to be aware of the potential risks associated with consuming food that has been treated with pesticides. Choosing to purchase organic produce, which is grown without the use of synthetic pesticides, is one way to reduce exposure to pesticide residues. Additionally, washing and thoroughly cooking fruits and vegetables can also help to reduce the presence of pesticide residues.

More information online

1. https://www.sciencedirect.com/science/article/pii/S2214999617302073 
2. https://www.sciencedirect.com/science/article/pii/S0003267008002441