¹Martyna Jakubowska,¹Jolanta Gałązka-Friedman,²Marek Woźniak,³Krzysztof Szopa,⁴Katarzyna Brzózka,⁵Barbora Pospíšilová,⁶Agnieszka Grabias
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70122]
¹Faculty of Physics, Warsaw University of Technology, Warsaw, Poland
²Faculty of Biology, University of Warsaw, Warsaw, Poland
³Faculty of Natural Sciences, University of Silesia, Sosnowiec, Poland
⁴Faculty of Mechanical Engineering, Casimir Pulaski Radom University, Radom, Poland
⁵Faculty of Science, Palack´y University Olomouc, Olomouc, Czech Republic
⁶Łukasiewicz Research Network—Institute of Microelectronics and Photonics, Warsaw, Poland
Published by arrangement with John Wiley & Sons

The paper presents a modified version of the 4M method, which is the latest method of classifying ordinary chondrites, based on their Mössbauer spectra measured at room temperature. The proposed changes, including the introduction of a new criterion for assessing which group (H, L, or LL) the meteorite being tested belong to, are expected to improve the plausibility of classification by the 4M method. The modification makes use of the Bayesian analysis and the maximum a posteriori probability. This modified version of the 4M method was tested by attempting to classify 20 samples of ordinary chondrites: 8 of type H, 7 of type L, and 5 of type LL. The results were compared with those obtained by the classical method of ordinary chondrite classification. The vast majority of classification tests performed using the new version of the 4M method were consistent with the classical method for group assignment, except for one L-type sample that was classified differently. It was also shown that the introduction of a new criterion resulted in a significantly better agreement with the established classification than in the case of the level of similarity criterion used in the previous version of the 4M method.

¹N. Randazzo,¹R. W. Hilts,²R. M. Whittal,²B. Reiz,¹V. Olan-Rubio,¹C. D. K. Herd,³I. H. Krouse
Meteoritics & Planetary Science (in Press) Open Access Link to Article [doi: 10.1111/maps.701271]
¹Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
²Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
³School of Science and Technology, Georgia Gwinnett College, Lawrenceville, Georgia, USA
Published by arrangement with John Wiley & Sons

Solvent extraction is a cornerstone of meteoritic organic and inorganic chemistry,yet the assumption that common solvents act as chemically inert media is becomingincreasingly untenable. This study reports that low-molecular-weight alcohols, particularlymethanol and ethanol, are “non-innocent” solvents when used to extract soluble sulfurspecies from carbonaceous chondrites. Laboratory extractions of Tagish Lake and Allendesamples demonstrate that these alcohols readily esterify meteoritic sulfate, producing largequantities of methyl and ethyl sulfate artifacts. Using isotopically labeled methanol(CD 3 OH) in 1:1 water mixtures, it is shown that >99% of the methyl sulfate signalpreviously attributed to indigenous methyl sulfate is actually solvent-derived. Correctedabundances fall from hundreds of nmol g1 reported in earlier studies to < 0.2 nmol g1 ,revealing that intrinsic methyl sulfate is only a trace constituent. Control experimentsindicate that esterification requires both acidic conditions and solid meteoritic matrices,implicating Fe-bearing phyllosilicates and oxides as heterogeneous catalysts. Additionalexperiments confirm that sulfate ester formation does not occur in solution-only systems,underscoring the catalytic role of mineral–solvent interfaces. These findings not onlynecessitate a downward revision of reported organosulfur inventories in carbonaceouschondrites but also highlight a broader issue: solvent-driven reactions can significantly alterthe apparent chemical record of extraterrestrial materials. It is recommended thatisotope-labeled solvents and mixed-solvent systems are employed as standard practice infuture extractions, both to minimize artifact generation and to maximize analyte coverageacross polarity ranges. Recognizing and mitigating solvent reactivity is essential for ensuringthat laboratory analyses faithfully represent intrinsic extraterrestrial chemistry rather thanexperimental artifacts.