Browsing by Author "Rosenau, Thomas"

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Not one size fits all: µ FTIR and pyrolysis GC MS for complementary analysis of microplastics in eutrophic surface water
(Analytical and Bioanalytical Chemistry, 2026-03-22) Omara, Timothy; Benetková, Barbora; Sumerskii, Ivan; Ssebugere, Patrick; Kyarimpa, Christine; Omwoma, Lugasi Solomon; Rosenau, Thomas; Nagawa, Christine Betty; Böhmdorfer, Stefan
This study reports large microplastics found in Lake Victoria through an analytical workflow that combines the complementary methods stereomicroscopy, micro-Fourier transform infrared (µ-FTIR) spectroscopy and pyrolysis gas chromatography-mass spectrometry (Pyr-GC-MS) for the quantification of 11 environmentally relevant microplastic polymers. Algae-rich surface water samples (n = 18) were trawled using a 0.3 mm manta net from Lake Victoria, the world’s largest tropical lake. Stereomicroscopy as a determinant analytical technique detected 191 particles, which were primarily blue fragments and fibres. Polyethylene and polypropylene were the dominant polymers identified by µ-FTIR. Pyr-GC-MS allowed the detection and quantification of microplastics (MPs) with LOD and LOQ of 0.01–14.7 µg and 0.03–49.1 µg. Polyethylene (0.058–0.34 µg/L), polypropylene (0.024 µg/L and 0.043 µg/L), nylon 6 (0.0051–0.064 µg/L), nylon 66 (0.0022–0.084 µg/L), poly(ethylene terephthalate) (0.0029–0.027 µg/L) and poly(methyl methacrylate) (0.0036 µg/L) were quantified. µ-FTIR was found to be suitable for the identification of the most abundant polymers in the 0.3–4.9 mm size range whereas Pyr-GC-MS afforded the quantification of seven polymers, most of which were not detected by µ-FTIR. This complementary workflow gave a wider perspective on MP loading, providing both polymer concentrations and physical characteristics (sizes, colours, forms and count) of the MPs.
Refined analysis of microplastics in endemic fish species from Lake Victoria using µ-FTIR and pyrolysis GC-MS
(Environmental Monitoring and Assessment, 2026-08-14) Omara, Timothy; Benetková, Barbora; Sumerskii, Ivan; Ssebugere, Patrick; Kyarimpa, Christine; Omwoma, Solomon Lugasi; Rosenau, Thomas; Nagawa, Christine Betty; Böhmdorfer, Stefan
Pyrolysis–gas chromatography–mass spectrometry (Pyr-GC-MS) has evolved into one of the most powerful methods for microplastics (MPs) analysis. However, analytical challenges are still encountered whenever Pyr-GC-MS is applied to matrices with high organic matter, protein and lipid contents. In this study, a workflow integrating stereomicroscopy, micro-Fourier transform infrared (µ-FTIR) spectroscopy and Pyr-GC-MS was extended to analyse MPs in three endemic fish species (Protopterus aethiopicus, Rastrineobola argentea and Synodontis victoriae) from Lake Victoria. Stereomicroscopic analysis only detected MPs in the gastrointestinal tracts of P. aethiopicus and S. victoriae, with the highest mean particle numbers being 16.0 ± 7.8 and 14.7 ± 6.7 items/fish taxon, respectively. No MPs were found in whole samples of R. argentea. The microparticles were mostly blue and brown 0.3–1.9-mm fragments and filaments, which µ-FTIR analysis confirmed to be composed of nylon 66, nylon 6/66, nylon 6/10, nylon 11, polyethylene and polypropylene. Retention time locking and post-column backflush considerably reduced the cycle time and increased stability of the Pyr-GC-MS method. Nylon 66 (243 µg/g in S. victoriae), nylon 6 (0.24–96 µg/g), polypropylene (6.4 µg/g in P. aethiopicus), poly(ethylene terephthalate) (1.2–107 µg/g) and styrene-butadiene rubber (8.5–34.8 µg/g) were quantified. Polyethylene and poly(methyl methacrylate) were detected below their limits of quantification. To prevent false positive detection of polyethylene in the lipid-rich tissues, the evaluation focussed on C21-α,ω-alkene as a marker. Polypropylene was not detected in some samples, as it formed several discrete propylene oligomers during pyrolysis, which suppressed the yield of its target quantification marker (2,4-dimethyl-1-heptene).