Feasibility studies of reference material for pesticide residue analysis
Scientists from the JRC's Institute for Reference Materials and Measurements (IRMM) performed a feasibility study for a cucumber reference material containing a mixture of 15 pesticides. Different aspects such as the type of material processing, homogeneity and stability were considered. The results revealed that the right conditions are available for preparing high water content vegetable certified reference material containing the selected pesticides.
Food products are regularly monitored for their pesticides content in order to ensure the safety of the products and therefore the health of consumers. For this purpose, food control laboratories need to analyse the amounts of pesticides in a variety of vegetables, fruits and other food products. To ensure the quality of the analytical data, certified reference materials (CRMs) are important. There is a lack of CRMs for pesticide analysis of vegetables with high water content such as cucumber.
As a result, the JRC-IRMM took the initiative of preparing a candidate reference material. One of the main challenges for the preparation of this matrix reference material is the tendency of some pesticides to degrade in the agricultural product.
Cucumber was spiked at 0.075 mg/kg with each of the 15 selected pesticides (acetamiprid, azoxystrobin, carbendazim, chlorpyrifos, cypermethrin, diazinon, (?+?)- endosulfan, fenitrothion, imazalil, imidacloprid, iprodione, malathion, methomyl, tebuconazole and thiabendazole) respectively. Three different strategies were considered for processing the material, based on the physicochemical properties of the vegetable and the target pesticides. The effects of processing and aspects related to the reconstitution of the material were evaluated by monitoring the pesticide levels in the three materials. For this purpose, two separate analytical methods based on LC-MS/MS and GC-MS/MS were developed and validated in-house. A spiked freeze-dried cucumber powder was selected as the most feasible material, and more exhaustive studies on homogeneity and stability of the pesticide residues in the matrix were carried out.
The findings of this study will not only provide useful knowledge for the future potential production of a matrix reference material for the selected pesticides in a high water content vegetable but also support the work of the European Union Reference Laboratory for pesticides residues analysis in fruit and vegetables.