Optimization of an analytical method to determine hormones in sea urchins

Abstract

The fact of preserving our environment from human impact has turned into a real challenge nowadays. The pollution issue leads to the contamination of marine habitats, resulting in the degradation of ecosystems. This brings out the need of developing methodologies to evaluate the compounds that are affecting marine organisms, in part due to the inefficient removal of toxic substances in WWTP, such as steroid hormones. The study of the presence of these compounds in marine organisms such as sea urchins is very interesting due to their role as bioindicators, since they feed on algae, and they are constantly in contact with the sediments. Owing to the low concentrations of steroid hormones in marine environments, it is necessary to develop extraction procedures that allow to extract and preconcentrate these pollutants prior to chemical analysis. Among the extraction methods, microwave-assisted extraction (MAE) has been used due to many advantages in comparison with traditional extraction techniques. In this regard, MAE presents easy handling of samples, uses low volumes of organic solvents, and provides very selective extractions. This study presents the optimization of MAE to extract and determine 15 hormones (five estrogens, three androgens, four progestogens and three glucocorticoids) in sea urchins. To perform the optimization, different variables that affect the extraction procedure (type of solvent, solvent volume, extraction time, extraction temperature and sample weight) have been studied following factorial experimental designs. The optimized extraction method, coupled to ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), showed very appropriate analytical parameters, with detection limits between 0.21 and 20.4 ng · g−1, being lower than 2.81 ng · g−1 for most of the compounds, and recovery extractions over 54.8%. After optimization, the analytical methodology was applied to samples of three different species of sea urchins of the Canary Islands (Arbacia lixula, Paracentrotus lividus and Sphaerechinus granularis) found in different locations around Gran Canaria Island (Spain).