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Item type:Publication, Access status: with files , Development of a multi-element quantification method for technical polymers containing refractory oxides after microwave-assisted digestion using HBF4(Royal Society of Chemistry (RSC), 2026-07-25); ; ; Polymers used in packaging, medical devices, and construction often contain inorganic additives, including stabilizers, fillers, pigments, and antioxidants. Quantitative elemental analysis of these additives is essential for quality control, regulatory compliance, recycling, and the assessment of microplastics, but is complicated by refractory oxides (e.g., TiO2, Al2O3, ZrO2) that are difficult to dissolve quantitatively. This study presents a two-step, microwave-assisted digestion method using tetrafluoroboric acid (HBF4) for comprehensive elemental analysis of technical polymers containing such oxides. In the first step, the polymer matrix is oxidized using HNO3 and H2O2 at 200 °C; and in the second step, HBF4 is added and digestion continues at 180 °C to dissolve refractory oxides while avoiding the use of free HF. Method development was performed on polyethylene containing various oxides, and on polyvinyl chloride containing metal soaps, CaCO3, and TiO2. The protocol was benchmarked against HF-based digestions. The optimized conditions (4 mL HNO3 + 1 mL H2O2, 75 min at 200 °C; 1 mL HBF4, 45 min at 180 °C) gave recoveries typically between 90 and 105% for Al, Ca, Mg, Ti, and Zr with relative standard deviations ≤5% for most analytes. Limits of detection by inductively coupled plasma mass spectrometry (ICP-MS) were ≤2.6 mg kg−1 (LOQs ≤8.5 mg kg−1) for most elements. Accuracy and applicability were confirmed for the polymer certified reference material ERM®-EC681k and for polycarbonate and acrylonitrile–butadiene–styrene masterbatches containing refractory oxides, demonstrating a robust, broadly applicable, and HF-free sample preparation strategy for elemental analysis of technical polymers and microplastics.Publicationtype: Journal Article42 131 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Highly siderophile element, triple oxygen-, ε¹⁸²W, and Re-Os isotopic composition of early Archean impact spherules from South Africa and the spherule–matrix complementarity(University of Arkansa, 2026-03-19); ; ; ; Archean impact spherule layers represent exceptional archives of extraterrestrial (ET) material, containing large amounts of ET highly siderophile elements (HSE) that dominate the bulk content of these elements. This enrichment makes them prime targets for testing additional impact tracers, such as ε¹⁸²W and triple oxygen isotopes. We investigated samples from the Paleoarchean BARB5 drill core (Barberton Mountain Land, South Africa), which preserves four spherule layers with chondritic HSE contents and ¹⁸⁷Os/¹⁸⁸Os signatures. Tungsten isotope data from bulk spherule layer samples yield ε¹⁸²W values indistinguishable from the bulk silicate Earth, most likely reflecting the limited sensitivity of the ε¹⁸²W composition to detect meteoritic admixture. If present, such a component must lie within analytical uncertainties, limiting contributions to ≤6% for a chondritic endmember or ≤3% for an iron-meteorite endmember, unless a larger signal was erased by postimpact hydrothermal overprint. In addition, bulk triple oxygen data fall within Archean shale fields and do not show resolvable ET signatures, consistent with a chondritic contribution of at most ~5% given analytical uncertainties; elevated ¹⁸O values most likely reflect seawater alteration of glass spherules. Thus, despite clear HSE–Os isotope evidence for admixture of ET components, ε¹⁸²W and oxygen isotopes yield no such information. This can be explained by plume condensation models predicting temporally separated fallout of refractory and volatile element carriers. To test this, we separated spherules, matrix, and mixed fractions from one of the four BARB5 beds. While the matrix hosts the highest HSE contents and least radiogenic ¹⁸⁷Os/¹⁸⁸Os, spherules have the lowest HSE contents and slightly more radiogenic ¹⁸⁷Os/¹⁸⁸Os signatures, with mixed fractions being intermediate. Together with highly siderophile interelement trends, these results most likely highlight stepwise condensation followed by early syn-depositional to diagenetic alteration, establishing Archean spherule beds as unique probes of early plume dynamics and impact processes.Publicationtype: Journal Article20 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Ruthenium isotopes show the Chicxulub impactor was a carbonaceous-type asteroid(American Association for the Advancement of Science (Assoc.), 2024-08-16)30