Japan Geoscience Union Meeting 2016

Presentation information


Symbol P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS12] Formation and evolution of planetary materials in the solar system

Tue. May 24, 2016 1:45 PM - 3:15 PM 104 (1F)

Convener:*Masaaki Miyahara(Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University), Akira Yamaguchi(National Institute of Polar Research), Tomohiro Usui(Department of Earth and Planetary Sciences,Tokyo Institute of Technology), Yoko Kebukawa(Faculty of Engineering, Yokohama National University), Wataru Fujiya(Ibaraki University, College of Science), Yusuke Seto(Graduate School of Science, Kobe University), Shoichi Itoh(Graduate school of Science, Kyoto University), Chair:Yoko Kebukawa(Faculty of Engineering, Yokohama National University)

2:00 PM - 2:15 PM

[PPS12-14] Chemistry of formaldehyde and ammonia in the Solar System small bodies

*Yoko Kebukawa1, Shusuke Misawa1, Jun Kawai1, Hajime Mita2, Keita Nanbu3, Takahito Ouchi3, Yasuji Muramatsu3, Shogo Tachibana4, Kensei Kobayashi1 (1.Yokohama National University, 2.Fukuoka Institute of Technology, 3.University of Hyogo, 4.Hokkaido University)

Keywords:Meteorites, Asteroids, Organic matter

Formaldehyde and ammonia is ubiquitous in the universe. Comets contain up to 4% H2CO and up to 1.5% NH3 relative to H2O, and interstellar medium (ISM) contains up to 8% H2CO and up to 80% NH3 relative to H2O [1]. Cody et al. [2] proposed the formation scenario of insoluble organic matter (IOM) in chondritic meteorites, in the presence of liquid water starting with formaldehyde and glycolaldehyde that is the simplest sugar produced by two H2CO molecules. We have conducted further experimental studies and showed that the presence of ammonia enhanced the IOM like organic solid formation via formose reaction followed by carbonization [3]. These studies were focusing on the solid materials, and now we study the liquid phase of the products with various analytical methods including electrospray ionization mass spectrometry (ESI-MS), X-ray absorption near edge structure (XANES), infrared spectroscopy and amino acid analyses using high performance liquid chromatography (HPLC).

Each starting solution contained 1mL water with 2 mmol formaldehyde, 1 mmol glycolaldehyde, 0.4 mmol ammonia (equivalent to H2O : C : N = 100 : 7.2 : 0.72) with catalytic amount of Ca(OH)2, and was sealed in a glass tube, then isothermally heated at 90 degrees C up to 250 degrees C. XANES and FTIR analyses showed that aromatic or olefinic C=C bond abundance increased with temperature in the soluble fractions. This indicates that the insoluble residues precipitate as a result of increase in the hydrophobic moieties in the products as the reaction proceeds. This is consistent with the previous results that the amount of insoluble fractions (organic solids) increases with temperature [3]. Acid hydrolysis of the solutions produced various amino acids up to four carbons. Alanine abundance was larger than glycine, and may indicate high abundance of methyl (-CH3) or methylene (-CH2-) substitutions in the amino acid precursor molecules. ESI-MS results suggested that various carbohydrates (CHO molecules) and these with nitrogen containing substitutions. This is somewhat consistent with ultrahigh-resolution ESI-MS analysis of the Murchison meteorite extract that shows various CHO and CHNO molecules [4], although only formaldehyde and ammonia chemistry cannot explain all of the diverse molecules found in this meteorite.

[1] Charnley, S. B. and Rodgers, S. D. (2008) Space Science Reviews, 138, 59-73.
[2] Cody, G. D., et al. (2011) Proceedings of the National Academy of Sciences of the United States of America, 108, 19171-19176.
[3] Kebukawa, Y., et al. (2013) The Astrophysical Journal, 771, 19.
[4] Schmitt-Kopplin, P., et al. (2010) Proceedings of the National Academy of Sciences of the United States of America, 107, 2763-2768.