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Abstract EANA2026-85 |
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Investigating the influence of iron minerals on organic compound detection in Mars analogue samples using Laser Desorption Mass Spectrometry
The detection of organic molecules in Martian surface and subsurface materials is a central objective of current and future Mars exploration, especially regarding the ExoMars Rosalind Franklin mission. Laser Desorption Mass Spectrometry (LDMS) provides a comparatively non-destructive first assessment of non-volatile organic compounds before more resource-intensive or destructive GC-MS analyses. However, one key-challenge is that organic compounds on Mars are expected to occur in close association with mineral matrices that can influence preservation, mobilization, ionisation and thus the analytical detectability.
Particularly iron minerals, which are widespread in Martian environments, can affect organic detectability in LDMS analyses through matrix effects such as surface adsorption, UV absorption, thermal conductivity, and mineral-specific chemical interactions. Understanding such matrix effects is essential for assessing whether weak or absent signals genuinely reflect low organic abundances or result from mineral-associated analytical suppression.
Here we present results of an investigation into how selected iron Martian analogue minerals influence the detection of organic molecules by LDMS. Specifically, we spiked Mars-analogue iron mineral phases, including hematite, lepidocrocite, ferrihydrite, and magnetite, with lipid-related organic model compounds, including cholesterol and selected fatty acids, and analysed the mixtures using an Atmospheric Pressure Matrix-Assisted Laser Desorption/Ionisation (AP-MALDI)-based LDMS setup. Preliminary LDMS data already indicate that cholesterol-related peaks can be strongly suppressed in the presence of certain iron (hydr)oxide mineral phases, highlighting the importance of understanding how mineral-dependent effects influence organic compound detectability.
This distinction is highly relevant for the interpretation of future Mars mission data, particularly data obtained with the Mars Organic Molecule Analyzer (MOMA) aboard the Rosalind Franklin rover, including the detection of potential organic biosignatures.