Técnicas cromatográficas acopladas a espectrometría de masas de baja y alta resolución aplicadas al análisis de contaminantes orgánicos en seguridad alimentaria y control ambiental

Abstract

In general terms, this Thesis entitled “Chromatographic techniques coupled to low and high resolution mass spectrometry applied to the analysis of organic contaminants in food safety and environmental control”, has been focused on the applicability of ultra-high liquid chromatography (UHPLC) and gas chromatography (GC) using low resolution (LRMS) and high resolution mass spectrometry (HRMS) analyzers for the analysis of contaminants in food and environmental samples. With this purpose, simple, reliable and rapid analytical methods using chromatographic techniques coupled to LRMS have been developed, optimized and validated for routine analysis. Likewise, a bibliographic review about last tendencies in the analysis of contaminants by GC-HRMS in the environmental field has been included. Therefore, depending on the nature of analyzed matrix, this Thesis is divided in two main sections for the determination of contaminants: i) food safety, focused on the applicability of UHPLC coupled to MS in tandem (MS/MS); and ii) environmental control, where GC-MS/MS and GC-HRMS are applied. In the first section of food safety, two analytical methods have been developed for the determination of nitrofuran metabolites (broadspectrum antibacterial drugs) in seafood and residues of pesticides in processed fruits by UHPLC-MS/MS. Extraction and clean-up (in the case of nitrofurans) procedures, as well as instrumental conditions for the chromatographic separation and detection of the analytes have been optimized in both works. Besides, current legislation in Europe Union (EU) was taken into account: the prohibition of nitrofurans in products of aquaculture and the establishment of a minimum required performance limit of 1 µg/kg (MRPL), as well as existing strict maximum limits of residues (MLRs) for pesticides in fresh fruits (MLRs have not been specifically established for processed fruit). Additionally, developed methods have been fully validated in terms of sensitivity, selectivity, accuracy and robustness in order to verify its applicability in routine analysis of samples and to ensure the reliability of results. Finally, both methodologies have been applied to the analysis of real food samples. Therefore, studies which have been included in this first section are listed below: Development and validation of an analytical method for the simultaneous determination of 4 nitrofuran metabolites in seafood by UHPLC-MS/MS. The extraction procedure was based on a simultaneous acidic hydrolysis and derivatization followed by a final step of clean-up by solid-phase extraction (SPE). The use of the UHPLC technique allowed reducing the time consumed during the chromatography analysis (5.5 min). It also increased the sensitivity, with the objective of obtaining equal or lower quantification limits (LOQs) than the MRPLs established by the EU. The method was applied to real food samples, but nitrofurans were not found. Development and validation of a reliable multiresidue analytical method for the simultaneous determination of 250 pesticides in processed fruit in a 16-min run by UHPLC-MS/MS. Extraction was performed applying a modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method without any clean-up step but including a dilution stage in order to obtain good peak shapes and reducing matrix effects. Finally, the developed method was applied to the routine analysis of 103 samples of different types of processed fruits (puree, concentrated puree, jam, pulp and fruit in syrup), detecting the presence of several pesticides residues such as fluopyram, spinosad or cyprodinil. The second section of environmental control was focused on the study of two families of ubiquitous and toxic contaminants (from industrial and anthropogenic sources) in environmental samples: persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs). In this context, published studies in this section are listed below: Bibliographic review of analytical methodologies used between 2005 and 2013 for the determination of POPs in water and sediments samples. This review includes extraction and cleaning methods, as well as the “state of art” of GC and HRMS techniques in this context. It also includes GC-HRMS applications and quantification strategies of real samples. Development of a sensitive analytical method for the determination of 12 PAHs (defined as priority pollutants by the EU and the United States Environmental Protection Agency), using GC-MS/MS. The main objective was achieving LOQs low enough according to the requirements of current legislation. The sample treatment was based on a SPE method. Additionally, the method was validated to ensure the reliability of results in four different types of water: seawater, drinking water, untreated inland water and wastewater. And finally, it was applied to routine analysis of aqueous samples, although PAHs above LOQs were not detected.