Determination of steroid hormones in sea urchins by microwave-assisted extraction and ultrahigh-performance liquid chromatography tandem mass spectrometry

Marine pollution poses significant threats to ecosystems by contaminating habitats and degrading marine life. This involves the need to develop efficient methodologies to evaluate the compounds that affect marine organisms, such as steroid hormones. The study of the presence of these compounds in marine organisms like sea urchins is very interesting given their role as bioindicators because they feed on algae and are constantly in contact with sediments. Given the low concentrations of steroid hormones in marine environments, it is necessary to develop extraction procedures that allow these pollutants to be extracted and preconcentrated before chemical analyses. Of all the extraction methods, microwave-assisted extraction (MAE) has been used for its many advantages compared to traditional extraction techniques, such as easy sample handling or scarce organic solvents use, and for providing very selective extractions. This study presents the novel MAE optimisation for the extraction of 15 hormones, including five oestrogens, three androgens, four progestogens and three glucocorticoids from sea urchin tissues. The extracted hormones were subsequently determined by high-performance liquid chromatography tandem mass spectrometry. To the best of the authors' knowledge, this approach has not been previously developed. To perform extraction optimisation, different variables were studied following factorial experimental designs. The optimised extraction method showed very appropriate analytical parameters, with limits of detection between 0.21 and 20.4 ng·g^-1 for the four families of studied steroid hormones, and recovery extractions over 60 % for most target compounds. After optimisation, the analytical methodology was applied to samples of three different sea urchins species (Arbacia lixula, Paracentrotus lividus, Sphaerechinus granularis) caught in different locations around the Gran Canaria island (Canary Islands, Spain). The results showed the great applicability of the optimised methodology and two target hormones, boldenone and prednisolone, which were quantified in different samples and locations. This indicates the potential of sea urchins as bioindicators of the health of marine ecosystems and of anthropogenic contamination.