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. Author manuscript; available in PMC: 2018 Aug 1.
Published in final edited form as: Astrobiology. 2017 Jul 19;17(8):761–770. doi: 10.1089/ast.2016.1613

Fig. 2.

Fig. 2

Structures of all possible singly and doubly oxidized purines (N-oxides excluded). The presence of hypoxanthine and xanthine have been confirmed using GC-MS by comparison with commercial standards. The remaining 4 compounds are hypothesized to also be present based on the mass spectra of several unidentified peaks in the chromatogram. However, no standards were commercially available for confirmation.