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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 4.

Fig 4

Top panel: (Top trace) Total-ion chromatogram (TIC) of the residue produced from a UV-irradiated H2O:NH3:purine ice. (Middle trace) Single-ion chromatogram (SIC) of the same residue for mass 367 Da. (Bottom trace) SIC of the guanine standard (mass 367 Da). Bottom panel: (Top trace) Mass spectrum of the peak identified as guanine in the residue produced from a UV-irradiated H2O:NH3:purine ice. (Middle trace) Mass spectrum of a guanine standard. (Bottom trace) Mass spectrum of the peak identified as guanine in the residue produced from a UV-irradiated ice containing H218O and 15NH3 instead of H2O and NH3, respectively. The observed mass increase matches what is expected for the guanine identification.