biostudies-literatureUnknown9(1)Toto BTo date, microplastic is ubiquitously encountered in the environment. Studies analyzing microplastic in terrestrial ecosystems, including animal feces and feed, are few. Microplastic quantification method validation and harmonization are not yet far developed. For the analysis of small microplastic, approximately <0.5 mm, extraction from organic and inorganic materials is fundamental prior to quantitative and qualitative analysis. Method validation, including recovery studies, are necessary throughout the analytical chain. In this study, we developed an optimized, efficient protocol with a duration of 72 h for the digestion of laboratory rat feed and feces. A combination of a mild acidic (H₂O₂ 15%; HNO₃ 5%) and an alkaline treatment (10% KOH) dissolving theHeliyone12811https://www.ebi.ac.uk/biostudies/studies/S-EPMC9876835biostudies-literatureEfficient extraction of small microplastic particles from rat feed and feces for quantification.PMC9876835Toto BKogel TDierkes JRefosco AfalseEfficient extraction of small microplastic particles from rat feed and feces for quantification.To date, microplastic is ubiquitously encountered in the environment. Studies analyzing microplastic in terrestrial ecosystems, including animal feces and feed, are few. Microplastic quantification method validation and harmonization are not yet far developed. For the analysis of small microplastic, approximately <0.5 mm, extraction from organic and inorganic materials is fundamental prior to quantitative and qualitative analysis. Method validation, including recovery studies, are necessary throughout the analytical chain. In this study, we developed an optimized, efficient protocol with a duration of 72 h for the digestion of laboratory rat feed and feces. A combination of a mild acidic (H₂O₂ 15%; HNO₃ 5%) and an alkaline treatment (10% KOH) dissolving the2023-01-01T00:00:00Z2023 Jan2025-04-27T00:53:41.395Z2025-04-06T18:02:22.232ZS-EPMC98768353671128910.1016/j.heliyon.2023.e12811