We conducted a coordinated analysis of 3 carbonaceous meteorites, which included the identification of sugars, stable carbon isotope analyses of the individual sugars, stable carbon isotope and stable nitrogen isotope analyses of IOM, molecular structure analysis of IOM, and an evaluation of the mineral alteration (SI Appendix, Fig. S1). The carbonaceous meteorites investigated in this study were 2 CR2 chondrites (NWA 801 and NWA 7020) and a CM2 chondrite (Murchison meteorite). Typically, CR2 chondrites contain larger amounts of soluble organic compounds, such as amino acids (8 , 33 (link)), compared with other meteorite types. The fragment of Murchison meteorite investigated in this study was already analyzed for amino acids, and it was established that this Murchison meteorite fragment experienced minimal terrestrial contamination based on a near-racemic (d ∼ l) mixture of the common biological amino acid alanine (34 (link)). Large fractions of the meteorites were used for sugar extraction (>2 g) because the sugar content was expected to be low.
The Murchison meteorite has been investigated for sugar and sugar-related compounds in previous studies (14 (link), 15 (link)). Unlike previous studies, we extracted sugars using hydrochloric acid and water from the meteorites to liberate all sugars from the mineral surfaces. Then, this extract was purified and derivatized into aldonitrile acetates (18 (link), 35 ). This derivatization has large advantages for the reliable identification and sensitive detection of sugars over traditional methods (SI Appendix, SI Text). This derivatization has been used for the analysis of carbon isotope compositions of sugars in biological samples (18 (link)).