Quantification of microplastics in environmental samples via pressurized liquid extraction and pyrolysis-gas chromatography
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The quantification of microplastics (MP) in environmental samples is currently a challenging task. To enable low quantification limits, an analytical method has been developed combining pressurized liquid extraction (PLE) and pyrolysis GC-MS. The automated extraction includes a pre-extraction step via methanol followed by a subsequent PLE using tetrahydrofuran. For the most frequently used synthetic polymers polyethylene (PE), polypropylene (PP), and polystyrene (PS), limits of quantification were achieved down to 0.007 mg/g. Recoveries above 80% were attained for solid matrices such as soil and sediments. The developed method was applied for MP quantification in environmental samples such as sediment, suspended matter, soil, and sewage sludge. In all these matrices, PE and PP were detected with concentrations ranging from 0.03 to 3.3 mg/g. In sewage sludge samples, all three polymers were present with concentration levels ranging between 0.08 ± 0.02 mg/g (PP) and 3.3 ± 0.3 mg/g (PE). However, especially for solid samples, the analysis of triplicates revealed elevated statistical uncertainties due to the inhomogeneous distribution of MP particles. Thus, care has to be taken when milling and homogenizing the samples due to the formation of agglomerates.
KeywordsMicroplastics Quantification Pressurized liquid extraction pyr-GC-MS
This work was part of the FONA project “Microplastics in Inland Waters - Investigation and Modeling of Entries and whereabouts in the Danube Area as a Basis for Action Planning (MicBin)” funded by the German Federal Ministry of Education and Research (BMBF).
Funding by the Federal Ministry of Transport and Digital Infrastructure (BMVI) is acknowledged. Tim Lauschke is thankful for financial support by University of Koblenz.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.
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