Currently, millions of tonnes of plastic waste per year end up polluting the marine environment and its biota. It can be said that what was initially conceived as a sustainable initiative, designed to reduce production costs and require fewer natural resources, has ended up becoming one of the main threats to the environment and human health in the 21st century. Humans are exposed to plastic-derived compounds through the consumption of fish and shellfish.

Mussels have become the main sentinels of the environmental quality of the sea, and in the specific case of the species Mytilus galloprovincialis, belonging to the family Mytilidae, native to the Mediterranean coastline, it is used as a bio-indicator of the level of pollution in the Mediterranean Sea. These molluscs are filter-feeding organisms and their continuous exposure to harmful substances in the water means that pollutants are retained and accumulated in their soft tissues and membranes.

In response to this problem, and to the need for reliable data on which to base future regulations governing the content of contaminants derived from plastics in seafood, the GTyMAQ research group (Techniques and Methods of Chemical Analysis), belonging to the Department of Analytical Sciences of the UNED, in collaboration with the Food and Agriculture Organization of the United Nations (FAO) and within the framework of the AVANSECAL-II-CM Programme (Integrated strategies for the improvement of the quality, safety and functionality of food: Towards a healthy diet) is currently dedicating one of its lines of research to the development of analytical methodologies for the determination, in seafood, of additive compounds (plasticisers and stabilisers) used in the manufacture of plastic, and other contaminants (pesticide residues) that may be absorbed in them.

In recent research, the GTyMAQ group has developed a determination method, based on the technique of high performance liquid chromatography with diode array (HPLC-DAD) coupled to mass spectrometry (MS), for the determination in samples of raw mussels from the Galician Rias of more than 8 additives used in the manufacture of plastics, such as diethyl phthalate (DEP), dibutyl phthalate (DBP), diethylhexyl phthalate (DHEP), bisphenol S (BPS), bisphenol F (BPF), bisphenol A (BPA), nonylphenol ethoxylate (NP-9), nonylphenol (NP) and 3 organochlorine pesticides (DDT (dichlorodiphenyltrichloroethane), DDE (dichlorodiphenyldichloroethylene) and DDD (dichlorodiphenyldichloroethane).

The analysis of these compounds in mussel samples requires prior treatment of the sample. In the case of the mussel sample, the digestive gland and soft tissues are processed and analysed, together with the lysosomal membrane that determines the so-called general stress of this species. In our studies, a method based on Matrix Solid Phase Dispersion (MSPD) was optimised for the raw mussel treatment step, which allowed us to efficiently extract the compounds, obtaining high recoveries of the analytes (80-100%). The sensitivity of the MSPD-HPLC-MS method developed was good, achieving detection and quantification limits between 0.06-6.00 and 0.25-16.22 μg/kg. The results showed that none of the mussel samples analysed showed contamination by these compounds.

Gema Paniagua González, Rosa Mª Garcinuño Martínez and Pilar Fernández Hernando.

Department of Analytical Sciences, UNED.

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