Zoological biobanks as a resource for microplastic analysis: a Py-GC-MS/MS case study on sea cucumbers

Microplastics have spread through every ecosystem studied. Yet, documenting their spatiotemporal distribution remains challenging, particularly in marine environments where sampling is costly and difficult. Archived specimens in zoological biobanks offer an underused resource for investigating microplastic contamination across all marine environments. However, their use requires careful experimental design. This study proposes an approach for detecting microplastics in biobanked sea cucumbers from the Atlantic Ocean and Mediterranean Sea. As deposit-feeders, they are in frontline of microplastics sinking to the seafloor and should thus give insights to the level of exposure to microplastic pollution in their natural habitats. We address and overcome critical methodological challenges associated with preserved specimens. We first verified that preservation solvents do not introduce significant external contamination. We then adapted state-of-the-art sample preparation protocols to quantify five common plastic polymers from sea cucumber intestines using pyrolysis–gas chromatography–tandem mass spectrometry after chemical digestion of the intestines. The optimized method demonstrates excellent robustness, with negligible procedural contamination and high purification rates that effectively eliminate tissue matrix before polymer analysis. Our analytical approach achieves low detection limits while confidently distinguishing polyethylene from confounding organic compounds like lipids. Analyzed specimens contained total polymer concentrations ranging from 9.4 to 169.2 µg per gram of dry matter, consistent with levels found in other marine organisms, and predominantly polyethylene terephthalate and polystyrene. This approach transforms existing museum collections into invaluable resources for documenting microplastic pollution across time and space.