AMINO ACID ANALYSES OF THE ANTARCTIC CM2 METEORITES ALH 83100 AND LEW 90500 USING LIQUID CHROMATOGRAPHY-TIME OF FLIGHT-MASS SPECTROMETRY. D. P. Glavin', J. P. Dworkin', A. Aubrey2, 0. Botta', J. H. Doty 1113, and J. L. Bada', 'NASA Goddard Space Flight Center, Greenbelt, MD 20771, daniel.p.rrlavin(~nasa.~ov2, S cripps Institution of Oceanography, University of Cali- fornia, San Diego, La Jolla, CA 92093, 3Dematha Catholic High School, Hyattsville, MD 20781. Introduction: The investigation of organic com- by using cation exchange resin (AG50W-X8, 100-200 pounds in primitive carbonaceous meteorites provides mesh, Bio-Rad) prior to HPLC-FD and LC-ToF-MS a record of the chemical processes that occurred in the analysis to determine the abundance of free amino early solar system. In particular, amino acids have acids associated with the bulk sample. The remaining been shown to be potential indicators in tracing the water supernatant was transferred to a separate test nature of carbonaceous chondrite parent bodies [ 13. tube, dried under vacuum, hydrolyzed under 6 M HCI The delivery of amino acids by carbonaceous chon- vapor at 150°C for 3 h, desalted, and analyzed by us- drites to the early Earth could have been any impor- ing OPAMAC derivatization and HPLC separation to tant source of the Earth's prebiotic organic inventory determine bound amino acids in the bulk sample [4]. [2]. Over 80 different amino acids have been detected Results and Discussion: The HPLC-FD and in the Murchison CM2 meteorite, most of them com- LC-ToF-MS chromatograms of the 6 M HCI- pletely non-existent in the terrestrial biosphere [3]. hydrolyzed, hot water extracts of the CM2 meteorites We have optimized a new liquid chromatography- ALH 83 100, LEW 90500 and Murchison and the ser- time of flight-mass spectrometry (LC-ToF-MS) tech- pentine blank are shown in Figure 1. The distributions nique coupled with OPAMAC derivatization in order of amino acids in the LEW 90500 and Murchison me- to detect amino acids in meteorite extracts by UV teorites were found to be nearly identical, which is fluorescence and exact mass simultaneously. The consistent with previous analyses of these two meteor- detection limit of the LC-ToF-MS instrument for ites [ 1, 51. The most abundant amino acids detected in amino acids is at least 3 orders of magnitude lower Murchison and LEW 90500 were a-aminoisobutyric than traditional GC-MS techniques. acid (AIB) and isovaline (1,300 to 3,200 ppb). In con- Here we report on the first analyses of amino acids trast, ALH 83100 contained a much lower abundance and their enantiomeric abundances in the CM2 carbo- of AIB (250 ppb) and isovaline (< 10 pp) compared to naceous meteorites ALH 83100, LEW 90500, and Murchison and LEW 90500. Therefore, if Strecker- Murchison using this new LC-ToF-MS instrument cyanohydrin synthesis was the predominant pathway configuration. Amino acid analyses of any kind for for the formation of amino acids on these CM meteor- the CM meteorite ALH 83100 have not previously ite parent bodies [ 1,6], then ALH 83 100 originated on been reported. a chemically distinct parent body that was depleted in Samples and Analytical Techniques: The acetone and 2-butanone required for the formation of Antarctic CM2 carbonaceous chondrites ALH 83 100 AIB and isovaline by Strecker [l]. (split 246, parent 26) and LEW 90500 (split 69, parent The most striking difference between ALH 83 100 1) were provided by the meteorite sample curator at and the other CMs was the large unidentified peak the NASA Johnson Space Center. The CM2 meteorite (marked 'X' in Fig. 1) present in the hydrolyzed ex- Murchison (USNM 6650.2) was provided by the tract of ALH 83 100 at a much higher concentration (- Smithsonian Museum of Natural History. The meteor- 8,500 ppb) than detected in Murchison (240 ppb) and ite samples were crushed into a fine powder with an LEW 90500 (390 ppb). Peak X was only detected at annealed (500°C overnight) mortar and pestle in a very low concentrations (- 150 ppb) in the water ex- positive pressure (I-pm filtered air) clean room. tract of ALH 83100 prior'to acid hydrolysis, which Crushed serpentine (a hydrated magnesium silicate) indicated that compound X was present in predomi- that had been heated at 500°C for several hours was nantly bound or peptide form. A peak with a similar used as a procedural blank. In addition, a sterile nylon retention time was also detected by HPLC-FD in a bag used to store the Antarctic meteorite samples after previous analysis of the Antarctic Martian meteorites collection was also analyzed in parallel. ALH 84001 and MIL 04436 [7, 81, however the mass A portion of each samplq (-50 to 200 mg) was of the compound was not determined. sealed in a clean glass test tube with 1 ml of double- Using HPLC-FD and LC-ToF-MS, we were able to distilled water for 24 h in a heating block set at 100°C. identify compound X in ALH 83100 as E-amino-n- The ampoules were cracked open and centrifuged to caproic acid (EACA) based on the exact molecular separate out the particulate from the water super- mass (m/z = 393.15, ES+ mode) and UV fluorescence natant. One half of the water extract was transferred retention time of the OPA/NAC derivative (Fig. 1). A to a new test tube, dried under vacuum and desalted high concentration of EACA was also identified in the AMINO ACIDS IN ANTARCTIC CM METEORITES: D. P. Glavin et al. 2006 acid hydrolyzed Nylon bag water extract. This result ple storage bags such as Teflon or polyethylene as an is not surprising since Nylon-6 is simply a peptide of alternative to Nylon-6. EACA and upon acid hydrolysis will yield large quan- References: [l] Ehrenfreund P. et al. (2001) tities of free EACA. PNAS, 98, 2138-2141. [2] Chyba C. and Sagan C. Conclusions: We have demonstrated that LC-ToF- (1992) Nature, 355, 125-132. [3] Botta 0. and Bada J. MS coupled with HPLC-FD detection is a very power- L. (2002) Sum. Geophys., 23, 411-467. [4] Glavin D. ful tool for the detection of amino acids in meteorite P. et al. (1999) Proc. Natl. Acad. Sci. USA, 96, 8835- extracts. Using this new analytical technique we were 8838. [5] Botta 0. and Bada J. L. (2002) LPSC able to identify a total of 20 different amino acids and XXXZZZ, abstract #1391, LPI, Houston (CD-ROM). [6] their enantiomers in the Antarctic CM meteorites Peltzer E. T. et ai. (1984) Ah. Space Res. 4, 69-74. ALH 83100 and LEW 90500, as well as the non- [7] Bada J. L. et al. (1998) Science 279, 362-365. [SI Antarctic CM Murchison. One amino acid that has Glavin D. P. et al. (2005) LPSC XXXVZ, abstract previously been detected in the Antarctic Martian me- #1920, LPI, Houston (CD-ROM). teorites ALH 84001 and MIL 03346, but has eluted Acknowledgements: The authors would like to identification, was also detected in the Antarctic me- thank K. Righter, T. McCoy and L. Welzenbach who teorites ALH 83100 and LEW 90500 and determined kindly provided the meteorite samples used in this by Le-ToF-MS to be EACA. EACA is a likely amino study. The NASA Astrobiology Institute and the acid contaminant derived from the nylon bag used to store the Antarctic meteorite samples. Fortunately, Goddard Center for Astrobiology (DPG, JPD, OB) Nylon-6 leaches only trace levels of other amino ac- and the NASA Specialized Center for Research and ids, however future meteorite collection efforts in Training in Exobiology (AA, JLB) for grant support. Antarctica should consider other types of sterile sam- (a) Standard HPLC with UV fluorescence (b) LC-ToF-MS '1 I "CX x S- *' I .3- vi LEW 90500 7 PE) a cC - e 5 0 .?- \ X = OPA/NAC labeled Ym E-aminn-n-cnproica cid 2 Murchison 1 "CY I2 34 56 2 SerpentineBlank 6 Si h~ 0 4 10 15 20 25 30 390 191 392 393 394 395 3% 397 3% Rctention Time (min) Mass (m/z) Figure 1. HPLC separation of OPANAC derivatives with simultaneous UV fluorescence and time of flight mass spectrometer (ToF-MS) detection of amino acids in the 6M HCI-hydrolyzed hot water extracts from the Antarctic CM2 carbonaceous chon- drites ALH 83100 and LEW 90500, the CM2 meteorite Murchison, and a serpentine blank (a). The ToF-MS ion trace shows the exact mass of the OPAINAC-E-amino-n-caproiacc id molecular ion as well as the mono-, di-, and tri-I3C species in both ES+ and ES- modes (b). The peaks were identified by comparison of the retention time and exact molecular mass to those in an amino acid standard run on the same day, as follows: I, D-aspartic acid; 2, L-aspartic acid; 3, L-glutamic acid; 4, D-glutamic acid; 5, D-serine; 6, L-serine; 7, glycine; 8, f3-alanine; 9, D-alanine; 10, y-amino-n-butyric acid; 1 1, L-alanine; 12, D-p-amino-n-butyric acid; 13, a-aminoisobutyric acid (AIB); 14, D,L-B-AIB; 15, L-f3-amino-n-butyrica cid; 16, D,L-a-amino-n-butyrica cid; 17, D- isovaline; 18, L-isovaline; 19, L-valine; and X, E-amino-n-caproic acid (EACA).