Development and preliminary validation of an analytical methodology for the determination of organic UV filters in zooplankton samples

The release of chemicals into marine environments from coastal human activities has raised growing concern about pollution. Among these chemicals, organic ultraviolet filters (oUVFs), widely used in personal care products and industrial applications, have recently been identified as pollutants of emerging concern. Their extensive use and persistence highlight the need to assess their occurrence and potential impacts on aquatic ecosystems. This study aimed to optimize and apply an analytical methodology for the determination of eleven oUVFs in zooplankton matrices. Microwave-assisted extraction (MAE) was employed for sample preparation, while ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) enabled the identification and quantification of the target compounds. Extraction parameters, including solvent, temperature, and time, were systematically optimized to enhance recovery and ensure accuracy and precision in complex biological samples. The method achieved limits of detection (MLOD) between 1.47 and 5.98 ng g −1 dry weight (d.w.) and method limits of quantification (MLOQ) between 4.900 and 19.92 ng g −1 d.w. Recovery efficiencies were low, ranging from 28 to 63 %, reflecting the diverse physicochemical properties of oUVFs and the strong matrix effects associated with zooplankton heterogeneity. Application of the validated method to zooplankton collected around Madeira Island (Portugal) revealed the presence of six oUVFs. Homosalate was the most frequently detected compound (53 % of samples), while octocrylene exhibited the highest concentrations, ranging from 24.01 to 1029 ng g −1 d.w. These findings demonstrate the relevance of zooplankton as bioindicators of oUVF contamination and support the need for regulatory monitoring and ecological risk assessments in coastal ecosystems.