Cyanide Abundance of Highly Aqueously Altered CM Chondrites

Asteroids, and the meteorites that come from them, retained the composition of the early Solar System and can give us insight to the processes that lead to the origin of life. The current NASA mission, OSIRIS-REx, has returned asteroid samples from the near-Earth asteroid Bennu. This asteroid is thought to be similar in composition to highly aqueously altered meteorites including CM1 and CM1/2 meteorites. Cyanide is thought to be an important molecule for prebiotic chemistry. Simple cyanide salts would have been the most accessible form of cyanide for reactions to occur; however, they may have recombined to form different metal-cyanide complexes most likely during the aqueous alteration stage(s). Understanding more about both the acid-releasable cyanide abundance and simple salt cyanide abundance of meteorites and asteroids will give insight to speciation of cyanide in these samples. This information will help in understanding cyanide’s role in prebiotic chemistry. Only one highly aqueously altered meteorite sample, and no asteroid samples, have been analyzed for acid-releasable cyanide abundance previously. In this work, I determined acid-releasable cyanide abundances for three highly aqueously altered meteorites and simple salt cyanide abundances for four highly aqueously altered meteorites using capillary-flow liquid chromatography high-resolution mass spectrometry. The most altered meteorite analyzed, a CM1, had the lowest abundance of acid-releasable cyanide present. The other two meteorites analyzed, both CM1/2s, had very similar cyanide abundances compared to one another and have a higher acid-releasable cyanide abundance than the CM1. However, there was only one meteorite that had a simple salt cyanide concentration above my detection limit. This concentration corresponded to less than 1% of the acid-releasable cyanide abundance for that meteorite. If Bennu is truly similar in composition to highly aqueously altered CM meteorites we expect to see acid-releasable cyanide present with very little of it being due to simple cyanide salts.