Toward Detecting Polycyclic Aromatic Hydrocarbons on Planetary Objects with ORIGIN

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are found on various planetary surfaces in the solar system. They are proposed to play a role in the emergence of life, as molecules that are important for biological processes could be derived from them. In this work, four PAHs (pyrene, perylene, anthracene, and coronene) were measured using the ORganics Information Gathering INstrument system (ORIGIN), a lightweight laser desorption ionization-mass spectrometer designed for space exploration missions. In this contribution, we demonstrate the current measurement capabilities of ORIGIN in detecting PAHs at different concentrations and applied laser pulse energies. Furthermore, we show that chemical processing of the PAHs during measurement is limited and that the parent mass can be detected in the majority of cases. The instrument achieves a 3σ detection limit in the order of femtomol mm−2 for all four PAHs, with the possibility of further increasing this sensitivity. This work illustrates the potential of ORIGIN as an instrument for the detection of molecules important for the emergence or presence of life, especially when viewed in combination with previous results by the instrument, such as the identification of amino acids. ORIGIN could be used on a lander or rover platform for future in situ missions to targets in the solar system, such as the icy moons of Jupiter or Saturn.

Correlation Network Analysis for Amino Acid Identification in Soil Samples With the ORIGIN Space-Prototype Instrument

“…It is intended to analyze non-volatile surface material by gentle desorption and soft ionization of molecules. ORIGIN is a particularly compact and sensitive instrument with proven capabilities to detect amino acids (Ligterink et al, 2020a), polycyclic aromatic hydrocarbons (PAHs) (Kipfer et al, 2022) and lipids (Boeren et al (in prep)). However, the majority of studies conducted with ORIGIN so far focused on fundamental studies conducted on reference samples, i.e., measurements of analytical grade preparations of single biomolecules or simple known mixtures thereof.…”

Detecting Lipids on Planetary Surfaces with Laser Desorption Ionization Mass Spectrometry

“…A mixture containing these two amino acids and four lipids (cholecalciferol, phylloquinone, 17αethynylestradiol, α-tocopherol) was prepared with a final concentration of 50 μM for each compound using a 1:1 isopropanol:water mixture as solvent. The third mixture consisted of two PAHs (investigated recently; see Kipfer et al 2022), namely, coronene and perylene, and four lipids (cholecalciferol, phylloquinone, 17α-ethynylestradiol, α-tocopherol) in isopropanol:heptane (1:1) at a final concentration of 25 μM for the PAHs and 50 μM for the lipids. Note that amino acids and PAHs could not be prepared in one sample mixture, due to insolubility of PAHs with any amount of water.…”

“…Measurements were performed with a laser pulse energy of ∼3 μJ on the surface, unless specified differently. This pulse energy was selected to allow for direct comparison with previous measurements of different compounds and to also assess the applicability of the measurement protocol (Ligterink et al 2020a;Kipfer et al 2022). A scan of laser power was performed for the cholecalciferol sample to evaluate the suitability of the laser pulse energy (see Appendix A).…”

“…Recently, our group developed a space prototype laser desorption ionization mass spectrometric system for the detection of biomolecules, called the ORganics Information Gathering INstrument (ORIGIN; Ligterink et al 2020a). Previous studies using ORIGIN focused on the analysis of amino acids and polycyclic aromatic hydrocarbons (PAHs; Ligterink et al 2020aLigterink et al , 2022Kipfer et al 2022;Schwander et al 2022). Unique and simple mass fragmentation patterns were observed for the amino acids, allowing for robust identification and quantification, while limited fragmentation for PAHs was observed and parent ions were identified.…”

“…Unique and simple mass fragmentation patterns were observed for the amino acids, allowing for robust identification and quantification, while limited fragmentation for PAHs was observed and parent ions were identified. The detection limits for both amino acids and PAHs were in the femtomol mm −2 range (Ligterink et al 2020a;Kipfer et al 2022). The influence of the presence of salt was investigated as well, as the presence of salt at percent level is expected on ocean worlds, and biosignature detection by current instruments, such as pyrolysis-GC-MS, can be extremely challenging in the presence of salt (Benner et al 2000;Navarro-González et al 2006;Montgomery et al 2019).…”