PMID- 31062993
OWN - NLM
STAT- MEDLINE
DCOM- 20200803
LR  - 20200803
IS  - 1557-8070 (Electronic)
IS  - 1557-8070 (Linking)
VI  - 19
IP  - 6
DP  - 2019 Jun
TI  - Effects of Oxygen-Containing Salts on the Detection of Organic Biomarkers on Mars 
      and in Terrestrial Analog Soils.
PG  - 711-721
LID - 10.1089/ast.2018.1888 [doi]
AB  - The detection of chlorinated hydrocarbons by Curiosity on Mars has been 
      attributed to the presence of unidentified indigenous organic matter. Similarly, 
      oxychlorines on Earth have been proposed to be responsible for the apparent lack 
      of organics in the Atacama Desert. The presence of perchlorate (ClO(4)(-)) poses 
      a unique challenge to the measurement of organic matter due to the oxidizing 
      power of oxychlorines during commonly used pyrolysis-gas chromatography-mass 
      spectrometry (py-GC-MS) methods. Here, we show that perchlorates and other 
      oxyanion salts inhibit the detection of organic compounds but that removing these 
      problematic species prior to pyrolysis by using an optimal sample extraction 
      duration and suitable ratios of water to sample mass enables analysis. We have 
      characterized leached and unleached samples containing perchlorates from the 
      Atacama Desert and have found that after leaching, the py-GC-MS chromatograms of 
      the dried mineral residues show identifiable biomarkers associated with 
      indigenous cyanobacteria. Samples which were pyrolyzed without leaching showed no 
      detectable organic matter other than background siloxane and very weak or no 
      trace of detectable polychlorinated benzenes. Dried sample residues remaining 
      after leaching, the mineral matrix and water-insoluble organic matter, showed a 
      strong organic response in all cases when analyzed by py-GC-MS. These residues 
      are most likely the product of the pyrolysis of water-insoluble organics 
      originally present in the samples. In addition, our results imply that previous 
      soil analyses which contained high levels of oxyanions and concluded that 
      organics were either not present or were present at extremely low levels should 
      be reexamined.
FAU - Montgomery, Wren
AU  - Montgomery W
AD  - 1 Department of Earth Science and Engineering, Imperial College London, London, 
      UK.
FAU - Jaramillo, Elizabeth A
AU  - Jaramillo EA
AD  - 2 Department of Chemistry, Tufts University, Medford, Massachusetts, USA.
FAU - Royle, Samuel H
AU  - Royle SH
AD  - 1 Department of Earth Science and Engineering, Imperial College London, London, 
      UK.
FAU - Kounaves, Samuel P
AU  - Kounaves SP
AD  - 1 Department of Earth Science and Engineering, Imperial College London, London, 
      UK.
AD  - 2 Department of Chemistry, Tufts University, Medford, Massachusetts, USA.
FAU - Schulze-Makuch, Dirk
AU  - Schulze-Makuch D
AD  - 3 Astrobiology Group, Center of Astronomy and Astrophysics, Technical University 
      of Berlin, Berlin, Germany.
FAU - Sephton, Mark A
AU  - Sephton MA
AD  - 1 Department of Earth Science and Engineering, Imperial College London, London, 
      UK.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20190507
PL  - United States
TA  - Astrobiology
JT  - Astrobiology
JID - 101088083
RN  - 0 (Environmental Biomarkers)
RN  - 0 (Organic Chemicals)
RN  - 0 (Perchlorates)
RN  - 0 (Soil)
SB  - IM
MH  - Desert Climate
MH  - *Environmental Biomarkers
MH  - Exobiology/methods
MH  - Extraterrestrial Environment/*chemistry
MH  - Gas Chromatography-Mass Spectrometry
MH  - *Mars
MH  - Organic Chemicals/*analysis/chemistry
MH  - Oxidation-Reduction
MH  - Perchlorates/*chemistry
MH  - Soil/chemistry
OTO - NOTNLM
OT  - Atacama
OT  - Detection
OT  - Mars
OT  - Organics
OT  - Perchlorate
OT  - Pyrolysis-gas chromatography-mass spectrometry
EDAT- 2019/05/08 06:00
MHDA- 2020/08/04 06:00
CRDT- 2019/05/08 06:00
PHST- 2019/05/08 06:00 [pubmed]
PHST- 2020/08/04 06:00 [medline]
PHST- 2019/05/08 06:00 [entrez]
AID - 10.1089/ast.2018.1888 [doi]
PST - ppublish
SO  - Astrobiology. 2019 Jun;19(6):711-721. doi: 10.1089/ast.2018.1888. Epub 2019 May 
      7.