Resumen de Emerging organic contaminants in aquatic organisms
Contamination of waters is a problem of concern and different groups of chemicals which are not included in current monitoring programs and referred as emerging organic contaminants (EOCs) are the focus of interest in the last decades. EOCs are a broadly group of chemical substances which include different compounds widely employed in different human and industrial activities.
Analytical methods have been developed so far to determine EOCs in different environmental samples, mainly in water compartments. Moreover, the scientific community has more recently also focused its interest on the determination of these EOCs in aquatic organisms. One concern of their presence is that they could bioaccumulate in aquatic organisms and produce side effects to them, another concern is regarded to their biomagnification through the food chain.
One of the main objectives of the present Doctoral Thesis is the development of new analytical methods to determine different EOCs in aquatic organisms. Moreover, another objective is to conduct an ecotoxicological study in the amphipod species Gammarus pulex.
In the present Doctoral Thesis, pharmaceuticals of widespread consumption, one personal care product (triclosan), iodinated X-ray contrast media (another group of pharmaceuticals employed in diagnostic medicine), and a group of high-intensity sweeteners were selected among the different EOCs. It should be highlighted that for these two latter groups of EOCs (iodinated X-ray contrast media and high-intensity sweeteners) no previous studies analysing them in aquatic organisms have emerged yet.
Regarding the development of analytical methods, they involve sample treatment, separation and detection. EOCs are expected to be present in the environment in low concentrations and at trace levels in aquatic organisms; moreover, these matrices represent an additional challenge due to its complexity as they are rich in endogenous components that could interfere with the analysis of EOCs. Due to the complexity of the matrix, special attention was paid to the sample treatment which includes extraction and clean-up. Two different extraction techniques have been evaluated to extract the compounds selected, which were pressurised liquid extraction and QuEChERS. Moreover, different clean-ups have also been evaluated in order to clean the extracts obtained and achieve suitable extracts to be analysed.
Analytical methods should allow the quantification of these EOCs at trace levels, to achieve this objective they are based on liquid chromatography or gas chromatography in combination with mass spectrometry, as it has the advantage of high selectivity, specificity and sensitivity. In the present Thesis due to the polarity of the analytes studied liquid chromatography was selected in all of the studies. Mass spectrometry was employed for the detection using the triple quadruple and high resolution mass spectrometry (Orbitrap) as analysers.
Fish species are the common organisms evaluated in studies to determine EOCs being the muscle tissue or the fish homogenate the common matrices studied. In the present Doctoral Thesis different fish species were selected as organism of interest to evaluate the presence of iodinated X-ray contrast media and high-intensity sweeteners. However, bivalves such as mussels are organisms also recently being studied. These organisms filter large volumes of water for feeding and breathing, therefore there are able to accumulate contaminants, moreover, they are representative of the local conditions due to their sessile behaviour. In the present Doctoral Thesis different bivalve species were selected to study the presence of different pharmaceuticals of widespread consumption.
Regarding the ecotoxicological study the toxicity of triclosan was evaluated in the amphipod species Gammarus pulex, in addition different populations that come from different environments with different degrees of pollution were evaluated in order to establish whether their resistance is similar or not.
