Extracting organic matter on Mars: A comparison of methods involving subcritical water, surfactant solutions and organic solvents

The first step in many life detection protocols on Mars involves attempts to extract or isolate organic matter from its mineral matrix. A number of extraction options are available and include heat and solvent assisted methods. Recent operations on Mars indicate that heating samples can cause the loss or obfuscation of organic signals from target materials, raising the importance of solvent-based systems for future missions. Several solvent types are available (e.g. organic solvents, surfactant based solvents and subcritical water extraction) but a comparison of their efficiencies in Mars relevant materials is missing. We have spiked the well characterised Mars analogue material JSC Mars-1 with a number of representative organic standards. Extraction of the spiked JSC Mars-1 with the three solvent methods provides insights into the relative efficiency of these methods and indicates how they may be used on future Mars missions. [Display omitted] •Solvent systems are needed to extract organic matter on Mars.•Organic solvent extraction is the most efficient and reproducible method for extracting organic compounds.•Subcritical water extraction outperforms surfactant-based methods in efficiency and reproducibility.•Extraction methods should be tailored to specific samples and detectors in life detection missions.