Potencial de l’espectrometria de masses per a l’anàlisi de contaminants ambientals i alimentaris

La presència de contaminants en el medi ambient i en els aliments és un tema d’important interès social que ha adquirit relevància en els últims anys. Entre els compostos que han suscitat més interès cal citar els que poden interferir amb el sistema endocrí dels éssers vius i que es coneixen amb el nom d’alteradors endocrins (endocrine disruptors, EDs). El motiu de preocupació es deu a l’observació d’efectes adversos en els éssers vius com són l’augment en la incidència de certes malalties en humans i alteracions en el sistema reproductor d’animals. Entre aquests compostos hom pot citar entre d’altres alguns pesticides i herbicides, els productes de degradació dels alquilfenols polietoxilats, certs productes farmacèutics i plastificants. La majoria d’aquests contaminants no estan encara regulats però són considerats contaminants emergents candidats a formar part en el futur de les llistes de compostos legislats. La seva inclusió en aquestes llistes depèn dels resultats dels estudis toxicològics i del seu potencial efecte sobre la salut. D’entre els alteradors endocrins en aquesta memòria s’ha estudiat el Bisfenol A (BPA) compost àmpliament utilitzat a la industria plàstica. L’elevada producció i utilització d’aquest compost fa que es trobi en el medi ambient i de fet, ha estat un compost força estudiat en els darrers anys. Atès que avui dia aquest compost comença a ser substituit per altres bisfenols (BPs) d’estructures similars és important desenvolupar metodologia anàlitica per a l’anàlisi d’aquests nous compostos. Un aspecte de la contaminació alimentària a la qual s’ha prestat relativament poca atenció és a la presència de contaminants que provenen de materials susceptibles d’entrar en contacte amb els aliments, com són els envasos, els utensilis de cuina, la maquinària emprada a la industria alimentària o els contenidors industrials. A la industria alimentaria s’utilitzen un seguit de materials com plàstics, cel•lulosa regenerada, paper i cartró (P&C), vidre, materials ceràmics, elastòmers, metalls, fusta, ceres, etc, i encara que aquests materials es formulen de manera que presentin unes propiètats físico-químiques adequades per protegir els aliments de canvis ambientals, químics i físics, petites quantitats dels constituents d’aquests materials poden migrar als aliments degut al contacte directe. Exemples de compostos que poden migrar cap als aliments són el propi bisfenol A així com els altres bisfenols i compostos relacionats emprats en la síntesi de les resines epoxi utilitzades per exemple en els recubriments de les llaunes de conserva. A més de la migració de contaminants deguda al contacte directe entre l’aliment i el material que els conté també es poden trobar als aliments altres components dels materials. Entre aquests compostos es poden citar els utilitzats en les tintes d’impressió dels empaquetaments. En aquesta memòria s’estudien els fotoiniciadors utilitzats en les tintes UV. En aquesta Tesi s’ha desenvolupat metodologia analítica basada en la cromatografia de líquids acoblada a l’espectrometria de masses en tàndem (LC-MS/MS) per a l’anàlisi de compostos àmpliament utilitzats en la fabricació d’envasos per a la industria alimentària com són el bisfenol A i compostos relacionats que s’utilitzen com a material de partida en la producció de plàstics i resines epoxi i els fotoiniciadors addicionats les tintes UV utilitzades en la impressió dels envasos.Food matrices are complex mixtures consisting of naturally found compounds, such as carbohydrates, lipids, proteins, vitamins, phenolic compounds and organic acids. On the other hand, compounds such as pesticides, polycyclic aromatic hydrocarbons, chlorinated and brominated compounds, veterinary drugs, toxins, migrants from containers, metals and inorganic compounds may also be present and need to be monitored. Strict regulations apply for many of these compounds, expressed by maximum residues levels (MRLs) and specific migration levels (SMLs). In order to comply with these regulations, highly selective and sensitive analytical methods are required to identify, confirm and quantify the targeted compounds. On the other hand, special attention may be taken into account on food packaging materials although the amount of material migrating from food packaging into food may well be 100 times higher than the pesticides or environmental pollutants contribution. Moreover, it is difficult to compare the toxicity (primarily acute) of well-controlled pesticides with the potential (primarily chronic) toxicity of frequently not even identified compounds entering food from packaging materials. Despite the efforts on food legislation and regulation, food safety incidents occasionally occur and can originate from different sources such as both microbial and chemical contaminants. On the last decade, some food safety incidents have been directly related to packaging materials such as the alert for food contamination by UV ink photoinitiators on November 2005 in Europe. The Italian Food Control Authority detected that the photoinitiator 2-isopropylthioxanthone (2-ITX) migrated into baby milk at concentrations ranging from 120 to 300 µg L-1, resulting in the withdrawal from the market of more than 30 million liters of milk. In order to protect the consumer from potential food risk hazards risk analysis are mandatory, and for that purpose hazard identification, hazard characterization, exposure assessment and risk characterization are necessary. For these reasons in this thesis different analytical methods based in liquid chromatography coupled to tandem mass spectrometry (LC-MS) have been developed for the analysis of packaged food. The studied compounds have been bisphenol A and related compounds used in canned foods and polycarbonate plastics, as well as some UV ink photoinitiators such as ITX, BP, EHDAB, DEAB, HCPK, PBZ,… The increasing need in food and environmental applications to cope with a growing number of analyses in very complex matrices demands new analytical procedures sensitive and fast enough but maintaining high resolution within an acceptable total analysis time. The purpose of this review is to describe new trends on current methodologies based on fast liquid chromatography for food and environmental analysis. It includes different column technologies, such as monolithic columns, sub-2 µm particle size columns, porous shell particles columns, as well as different stationary phases such as reversed phase (C8 and C18), hydrophilic interaction liquid chromatography (HILIC) and fluorinated ones. Additionally, recent sample treatments methodologies applied to reduce sample manipulation and total analysis time in food and environmental analysis - QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe), on line solid phase extraction coupled to ultra-performance liquid chromatography (on line SPE – UHPLC), turbo-flow chromatography (TFC) and molecular imprinted polimers (MIP), were also addressed. Some advantages but also drawbacks of many of these approaches focused in developing sensitive and fast chromatographic methods for food and environmental analysis and the way some authors solve them will also be discussed by means of some relevant applications. mention food packaging materials although the amount of material migrating from food packaging into food may well be 100 times higher than the pesticides or environmental pollutants contribution. Moreover, it is difficult to compare the toxicity (primarily acute) of well-controlled pesticides with the potential (primarily chronic) toxicity of frequently not even identified compounds entering food from packaging materials. Despite the efforts on food legislation and regulation, food safety incidents occasionally occur and can originate from different sources such as both microbial and chemical contaminants. On the last decade, some food safety incidents have been directly related to packaging materials such as the alert for food contamination by UV ink photoinitiators on November 2005 in Europe [3]. The Italian Food Control Authority detected that the photoinitiator 2-isopropylthioxanthone (2-ITX) migrated into baby milk at concentrations ranging from 120 to 300 µg L-1, resulting in the withdrawal from the market of more than 30 million liters of milk. In order to protect the consumer from potential food risk hazards risk analysis are mandatory, and for that purpose hazard identification, hazard characterization, exposure assessment and risk characterization are necessary. A very important prerequisite for performing risk assessment adequately is the presence of data generated by reliable and fit-for-purpose analytical methods to estimate the level of exposure and intake of the consumer to contaminants and residues. Focusing on contaminants coming from packaging materials regulation must also be coherent