Laser mass spectrometric detection of terrestrial and extraterrestrial polycyclic aromatic hydrocarbons
Microprobe laser-desorption laser-ionization mass spectrometry (μL 2MS) was used to study polycyclic aromatic hydrocarbons (PAHs) in both terrestrial and extraterrestrial materials, including: Kamchatkan hydrothermal vents, comet 81P/Wild 2 coma particles, as well as during an artificial meteor event.
Gas chromatography mass spectrometry and μL2MS analysis of hydrothermal vent samples from Kamchatka, Russia revealed significant sources of contamination, resulting from solid phase extraction (SPE) cartridges as well as from long-term vial storage. Future sampling protocols should include preconditioned SPE filters that have glass cartridges, as well as same-day GCMS and μL2MS analyses for each sample.
NASA Stardust contamination control analyses were carried out using μL2MS. Stardust flight spare aerogels showed mostly no PAHs; several exhibited easily identifiable, low-intensity PAHs. Other controls showed no evidence of PAHs at normal μL2MS operating parameters. Stardust heat shield char showed a consistent pattern of PAHs. A conservative baseline for the amount of contamination present in returned NASA Stardust samples was obtained.
μL2MS analysis of glass bead hypervelocity impact tracks in Stardust-type aerogel revealed some PAHs. Pulsed heating of aerogel showed a similar peak envelope, indicating that PAH synthesis or release is occurring during particle capture. Indigenous Allende meteorite and Illinois coal PAHs were detected along their respective impact tracks in aerogel. This indicates that in situ analysis of ablated particle debris is possible; however, ablated particle material was found to not faithfully represent the organic composition of an impactor.
One 81P/Wild 2 cometary sample exhibited evidence of PAHs, which correlated with at least 2 ppm of mass 252 (e.g., perylene) in the impacting particle. A lack of detectable, non-terrestrial PAHs in other samples implies that analyzed cometary particles were mostly devoid of PAHs above μL2MS detection limits.
Stardust heat shield material was treated as an artificial meteor to test atmospheric entry effects on meteoric organic compounds. PAHs in depth cores from both the SRC and an analogous are jet laboratory simulated model were analyzed with μL2MS, revealing a complex distribution of aromatic compounds at the heat shield surface. Results show that complex organic synthesis can readily occur during meteor events using precursors in the reentering body.
0768: Environmental science