Aplicación de técnicas de espectrometría de masas de baja y alta resolución para el estudio de plaguicidas y sus metabolitos en muestras alimentarias y ambientales

Laburpena

The Thesis herein entitled "Application of low and high resolution mass spectrometry techniques for the study of pesticides and their metabolites in food and environmental samples" has explored the resolution of analytical problems related to food and environmental safety from two perspectives: (i) the potential of GC and LC techniques coupled to low and high resolution mass spectrometry in targeted and non-targeted pesticide analysis strategies; (ii) the knowledge of the kinetic behaviour in soil, water and vegetables of pesticides after application as plant protection products, with special attention to the corresponding degradation products. The potential for transferring the results of the research contained in this Thesis to routine laboratories has also been taken into special consideration. Proof of this is that the analytical methods have been validated according to international guidelines and taking into account limiting factors such as the availability of standards or methods in which the identification is carried out through the comparison of spectrometric signals with spectral libraries. In all the studies carried out on agri-food or environmental samples, extraction methods based on the QUECHERS procedure are optimized. The work carried out in this Thesis has been structured in two blocks according to the subject matter, food safety assessment and dissipation and/or degradation kinetics. The first section deals with the development and validation of single and multi-residue analytical methods in different food matrices using LC-MS/MS and GC-HRMS; the following aspects are highlited: Firstly, an analytical method based on LC-MS/MS is developed and validated for the quantification and confirmation of the herbicide propoxycarbazone and its metabolite, 2-hydroxy-propoxycarbazone, in foods with very different characteristics such as honey, lettuce, soybean meal and beetroot. The method was applied to real samples, although none of these compounds were found above the maximum residue limit (MRL) in any of them. Secondly, the potential of the GC-HRMS technique for pesticide residues monitoring in food samples with Orbitrap analyser was then evaluated with the development of a multi-residue targeted analysis method with 200 pesticides from different pesticide families, in combination with a non-targeted analysis method. The targeted analysis method has been validated on strawberry, banana, pear and watermelon and subsequently applied to 31 real samples. The non-targeted analysis method is applied to 114 real samples including, in addition to the 31 samples, other samples as diverse as mushrooms, asparagus, peppers and plums. In a second section, the kinetic behaviour of dissipation and degradation of two pesticides that are the active ingredient of two plant protection products is studied in depth; one of the studies has been carried out in agri-food matrices and two others have been carried out in environmental matrices, using LC-HRMS. The dissipation and degradation studies included in this block were as follows: Laboratory tests on soil and water, scenario in which environmental conditions can be controlled during the study. The pesticide under investigation was the herbicide propoxycarbazone, which is applied on soil and can reach both groundwater (percolation) and surface water (runoff); therefore both matrices were considered. The study includes the tentative identification of propoxycarbazone metabolites generated in the degradation process. Field tests, specifically in greenhouses on cherry tomato and cucumber crops, and therefore exposed to real environmental conditions. The pesticide under study was the fungicide fluopyram, authorised for both crops and applied via irrigation water. The study includes the tentative identification of fluopyram metabolites generated in the degradation process.