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There is a strong need for careful quality control in hydrogen compound-specific stable isotope analysis (CSIA) of halogenated compounds. This arises in part due to the lack of universal design of the chromium (Cr) reactors. In this study, factors that optimize the critical performance parameter, linearity, for the Cr reduction method for hydrogen isotope analysis were identified and evaluated. These include the effects of short and long vertically mounted reactors and temperature profiles on trapping of Cl to ensure accurate and precise hydrogen isotope measurements. This paper demonstrates the critical parameters that need consideration to optimize any Cr reactor applications to ensure the accuracy of δH analysis for organic compounds and to enhance intercomparability for both international standards and reference materials run by continuous flow versus an elemental analyzer.
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http://dx.doi.org/10.1021/acs.analchem.9b04737 | DOI Listing |
J Comput Chem
September 2025
Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Leipzig University, Leipzig, Germany.
We investigated primary and secondary geometric isotope effects (H, D, T) on charge-inverted hydrogen bonds (CIHB) and dihydrogen bonds (DHB) using nuclear-electronic orbital density functional theory (NEO-DFT). The dianionic but electrophilic boron cluster [BH] served as a bonding partner, exhibiting a negatively polarized hydrogen atom in the BH bond. CIHB systems included interactions with Lewis acids (AlH, BH, GaH) and carbenes (CF, CCl, CBr), while DHBs were analyzed with NH, HF, HCl, and HBr.
View Article and Find Full Text PDFNature
September 2025
Natural History Sciences, IIL, Hokkaido University, Sapporo, Japan.
Carbonaceous asteroids are the source of the most primitive meteorites and represent leftover planetesimals that formed from ice and dust in the outer Solar System and may have delivered volatiles to the terrestrial planets. Understanding the aqueous activity of asteroids is key to deciphering their thermal, chemical and orbital evolution, with implications for the origin of water on the terrestrial planets. Analyses of the objects, in particular pristine samples returned from asteroid Ryugu, have provided detailed information on fluid-rock interactions within a few million years after parent-body formation.
View Article and Find Full Text PDFJ Lipid Res
September 2025
Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8. Electronic address:
Young females have higher circulating docosahexaenoic acid (DHA) levels than males, though the metabolic basis remains incompletely understood. Building on previous findings demonstrating higher hepatic synthesis of the DHA precursor, docosapentaenoic acid (DPAn-3) in males, this study extends the investigation to n-3 PUFA turnover in extrahepatic tissues of male and female C57BL/6N mice using compound-specific isotope analysis (CSIA). Animals were fed a 12-week diet enriched in either α-linolenic acid (ALA), eicosapentaenoic acid (EPA), or DHA, starting with a 4-week phase containing low carbon-13 (δC)-n-3 PUFA, followed by an 8-week phase with high δC-n-3 PUFA (n = 4 per diet, time point, sex).
View Article and Find Full Text PDFPLoS One
September 2025
Department of Archaeology and Heritage Studies, School of Culture and Society, Aarhus University, Højbjerg, Denmark.
This article presents a multiproxy investigation of metal samples obtained from 48 Nuragic figurines (so-called bronzetti) and three copper bun ingots. These objects originate from three prominent Sardinian sanctuaries and one unidentified site, dating to the late Nuragic period of the early first millennium BCE. The dataset significantly expands the existing scientific database and unwraps the complex fabrication biographies of the figurines from ore to finished object.
View Article and Find Full Text PDFPLoS One
September 2025
University of Groningen, Centre for Isotope Research, Groningen, the Netherlands.
The huge volcanic eruption at Thera (Santorini), situated in the Aegean Sea, occurred within the Late Minoan IA archaeological period. However, its temporal association with Egyptian history has long been a controversial subject. Traditionally, the eruption was placed in the early 18th Dynasty, associated with Pharaoh Thutmose III as the youngest option or with Pharaoh Nebpehtire Ahmose as the oldest possibility.
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