1:45 PM - 2:00 PM
[PPS12-13] Extraterrestrial organic compound distribution revealed by ultra-high resolution HPLC-MS
Keywords:extraterrestrial organic compounds, chemical evolution, carbonaceous meteorite, ultra-high resolution liquid chromatography, ultra-high resolution mass spectrometry
In this study, we further examine the distribution of soluble organic compound using ultrahigh-resolution HPLC/MS in order to investigate reaction mechanisms for extraterrestrial molecular evolution. The exact mass between the observed mass and calculated values matched within 1 ppm. Using a hydrophilic interaction liquid chromatography (HILIC) mode, complex compound mixtures were observed with mass peaks between m/z 80 and 1400, where strong ion peaks are distinguished between m/z 90 and 400 with the maximum at m/z ~300. Most peaks have CHN in composition with minor CHO and CHNO compositions. More than ~600 peaks match with the calculated masses for CnHmN+ and CnHmN2+ with the range of 5 < n < 33. Extensive alkylated N-containing cyclic compounds are distinguished by every 14.0156 (-CH2-) difference, which consisted of CnH2n-4N+, CnH2n-6N+, CnH2n-8N+, CnH2n-10N+ and CnH2n-12N+ in the earlier retention time, and the CnH2n+4N+, CnH2n+2N+, CnH2nN+, CnH2n-2N+, CnH2n+3N2+, CnH2n+1N2+, CnH2n-1N2+ and CnH2n-3N2+ in the later retention time. In addition to the predominant CnH2n-4N+ (saturate-alkylated pyridines, CnH2n-5N) and CnH2n-6N+ (unsaturate-alkylated pyridines, CnH2n-7N), alkylated imidazole homologues were identified by MS/MS analysis. Both alkylpyridines and alkylimidazoles could be produced from aldehydes and ammonia through aldol condensation and imine formation under an alkaline environment. Further redox reactions could have proceeded during water-rock interaction to give alkylpiperidines and pyridine carboxylic acids. Aldehyde polymerization with ammonia is an important pathway to produce the relatively high-molecular alkylated N-containing cyclic compounds on the meteorite parent body.