Extraterrestrial organic compounds and cyanide in the CM2 carbonaceous chondrites Aguas Zarcas and Murchison

Abstract

Evaluating the water‐soluble organic composition of carbonaceous chondrites is key to understanding the inventory of organic matter present at the origins of the solar system and the subsequent processes that took place inside asteroid parent bodies. Here, we present a side‐by‐side analysis and comparison of the abundance and molecular distribution of aliphatic amines, aldehydes, ketones, mono‐ and dicarboxylic acids, and free and acid‐releasable cyanide species in the CM2 chondrites Aguas Zarcas and Murchison. The Aguas Zarcas meteorite is a recent fall that occurred in central Costa Rica and constitutes the largest recovered mass of a CM‐type meteorite after Murchison. The overall content of organic species we investigated was systematically higher in Murchison than in Aguas Zarcas. Similar to previous meteoritic organic studies, carboxylic acids were one to two orders of magnitude more abundant than other soluble organic compound classes investigated in both meteorite samples. We did not identify free cyanide in Aguas Zarcas and Murchison; however, cyanide species analyzed after acid digestion of the water‐extracted meteorite mineral matrix were detected and quantified at slightly higher abundances in Aguas Zarcas compared to Murchison. Although there were differences in the total abundances of specific compound classes, these two carbonaceous chondrites showed similar isomeric distributions of aliphatic amines and carboxylic acids, with common traits such as a complete suite of structural isomers that decreases in concentration with increasing molecular weight. These observations agree with their petrologic CM type‐2 classification, suggesting that these meteorites experienced similar organic formation processes and/or conditions during parent body aqueous alteration.

Distinguishing between terrestrial and extraterrestrial organic compounds in the CM2 Aguas Zarcas carbonaceous chondrite: Implications for intrinsic organic matter

“…The remaining Aguas Zarcas specimens contained only a handful of intrinsic compounds, ranging from one to four. The intrinsic compounds acetic acid, adipic acid, butanedioic acid, propanedioic acid, glycine, fumaric acid, and hydrogen cyanide have been reported in other studies of Aguas Zarcas (Aponte et al, 2020;Glavin et al, 2020;Pizzarello et al, 2020). The remainder of the intrinsic compounds in the water extracts in Aguas Zarcas are found in other carbonaceous chondrites like Murchison and Tagish Lake (Jungclaus et al, 1976;Kminek et al, 2002;Koga & Naraoka, 2017;Pizzarello et al, 2001).…”

“…Only one dicarboxylic acid, butanedioic acid, was found in common between this study and our findings. Aponte et al (2020) derivatized water extracts of Aguas Zarcas with pentafluorobenzylhydroxylamine (PFBHA) and reported them to be rich in carboxylic acids. Five compounds, acetic acid, adipic acid, butanedioic acid, fumaric acid, and hydrogen cyanide, were found in both our study and the Aponte et al (2020) study.…”

“…Aponte et al (2020) derivatized water extracts of Aguas Zarcas with pentafluorobenzylhydroxylamine (PFBHA) and reported them to be rich in carboxylic acids. Five compounds, acetic acid, adipic acid, butanedioic acid, fumaric acid, and hydrogen cyanide, were found in both our study and the Aponte et al (2020) study. Last, Glavin et al (2020) determined their o-Phthalaldelhyde-N-acetylcysteine polyamine (OPA-NAC) derivatized Aguas Zarcas water extracts to be rich in aamino acids, with only glycine in common with our study.…”

Organic compounds in the Tarda C2 ungrouped carbonaceous chondrite: Evaluating the sources of contamination in a desert fall

“…There are 10 and 6 intrinsic compounds detected in that hot water extracts of Tarda A and Tarda B, respectively, which include monocarboxylic acids, dicarboxylic acids, amino acids, carbamides, and elemental sulfur compounds (Table 5). This suite of organic compounds has also been found in other carbonaceous chondrites such as Murchison, Tagish Lake, and Aguas Zarcas (Aponte et al, 2020;Glavin et al, 2021;Hayatsu et al, 1975;Kminek et al, 2002;Koga & Naraoka, 2017). Glycine was also detected in the procedural blank, but part of the peak area is still identified as an intrinsic compound in Table 5.…”

Impact of Phyllosilicates on Amino Acid Formation under Asteroidal Conditions

“…Samples were analyzed in triplicate. This method is robust and rapid, and has been used for many studies (see for example [41][42][43] ). The insensitivity to dissolved salts 44 permits the analysis of samples without the need for prederivatization desalting, however the fluorescent product is not a diastereomer and does not permit chiral separation of amino acids, seen in other methods 45 .…”