Browsing by Author "Simkus, Danielle N."
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- ItemCold curation of pristine astromaterials: insights from the Tagish Lake meteorite(2016) Herd, Christopher D. K.; Hilts, Robert; Skelhorne, Aaron W.; Simkus, Danielle N.The curation and handling of volatile-bearing astromaterials is of prime importance in current and future plans for sample return missions to targets containing organic compounds, ices, or other volatile components. We report on the specific curation constraints required for the preservation of the Tagish Lake meteorite, a C2 ungrouped chondrite that contains significant concentrations of organic matter, including compounds of prebiotic interest or volatile in character, and which was recovered from a frozen lake surface a few days after its fall. Here we review the circumstances of the meteorite’s handling, its complement of intrinsic and contaminant organic compounds, and an unusual reaction between some of the specimens and the Al foil in which they were enclosed. From our results we derive the requirements for curation of the meteorite, and describe a specialized facility that enables its curation and handling. The Subzero Facility for Curation of Astromaterials consists of a purified Ar glove box enclosed within a freezer chamber, and enables investigations relevant to curation of samples at or below -10 °C. We provide several recommendations based on insights obtained from the commissioning and initial use of the facility that are relevant to collection of freshly fallen meteorites, curation of volatile-bearing meteorites and other astromaterials, and planning and implementation of curation plans for future sample return missions to volatile-bearing targets.
- ItemCompound-specific carbon isotope compositions of aldehydes and ketones in the Tagish Lake meteorite(2016) Simkus, Danielle N.; Aponte, José C.; Hilts, Robert; Elsila, Jamie E.; Herd, Christopher D. K.Investigating the aldehyde and ketone content of astromaterials provides insight into the abiotic formation of prebiotic compounds on asteroid parent bodies, as aldehydes and ketones are the chemical precursors to α-amino acids in Strecker synthesis reactions. Elucidating amino acid synthesis reactions is important for understanding the origin of prebiotic compounds on Earth and the potential for life beyond our planet. Aldehydes and ketones have been previously detected via gas chromatography mass spectrometry (GC-MS) in a few carbonaceous chondrite meteorites, including Murchison, Bells and Ivuna. However, carbon isotope compositions of aldehydes and ketones in meteorites have not yet been measured. As such, their relationship to amino acids and other compound classes in meteorites have not been fully investigated. Here, we present the first report of compound specific carbon isotope measurements of aldehydes and ketones in meteorite samples.
- ItemCompound‐specific carbon isotope compositions of aldehydes and ketones in the Murchison meteorite(2019) Simkus, Danielle N.; Aponte, José C.; Hilts, Robert; Elsila, Jamie E.; Herd, Christopher D. K.Compound‐specific carbon isotope analysis (δ13C) of meteoritic organic compounds can be used to elucidate the abiotic chemical reactions involved in their synthesis. The soluble organic content of the Murchison carbonaceous chondrite has been extensively investigated over the years, with a focus on the origins of amino acids and the potential role of Strecker‐cyanohydrin synthesis in the early solar system. Previous δ13C investigations have targeted α‐amino acid and α‐hydroxy acid Strecker products and reactant HCN; however, δ13C values for meteoritic aldehydes and ketones (Strecker precursors) have not yet been reported. As such, the distribution of aldehydes and ketones in the cosmos and their role in prebiotic reactions have not been fully investigated. Here, we have applied an optimized O‐(2,3,4,5,6‐pentafluorobenzyl)hydroxylamine (PFBHA) derivatization procedure to the extraction, identification, and δ13C analysis of carbonyl compounds in the Murchison meteorite. A suite of aldehydes and ketones, dominated by acetaldehyde, propionaldehyde, and acetone, were detected in the sample. δ13C values, ranging from −10.0‰ to +66.4‰, were more 13C‐depleted than would be expected for aldehydes and ketones derived from the interstellar medium, based on interstellar 12C/13C ratios. These relatively 13C‐depleted values suggest that chemical processes taking place in asteroid parent bodies (e.g., oxidation of the IOM) may provide a secondary source of aldehydes and ketones in the solar system. Comparisons between δ13C compositions of meteoritic aldehydes and ketones and other organic compound classes were used to evaluate potential structural relationships and associated reactions, including Strecker synthesis and alteration‐driven chemical pathways.
- ItemDevelopment of a GC-MS-SPME method for the determination of amines in meteorites(2016) Hilts, Robert; Skelhorne, Aaron W.; Simkus, Danielle N.; Herd, Christopher D. K.A GC-MS-SPME analytical method for the direct determination of amines in aqueous solution has been developed. The key step in the procedure is the conversion of the amines into their non-volatile ammonium salts by protonation with HCl.
- ItemDevelopment of a new SPME-GCMS method for the determination of amines in meteorites(2016) Hilts, Robert; Skelhorne, Aaron W.; Herd, Christopher D. K.; Simkus, Danielle N.Introduction: Amines are polar, water-soluble organics found in all meteorites that contain amino acids. It has been proposed that meteoritic amines are produced by the thermal decarboxylation of amino acids[1]. The analysis of amines using GC-MS techniques has proven to be problematical owing to the high water solubility and high volatility of these compounds. In addition, the strong interactions of polar amine molecules with the stationary phase of a typical polysiloxane column lead to extensive tailing, poor resolution of peaks and low detector response [2]. To circumvent these disadvantages the highly polar amines have been converted to less polar derivatives that are more amenable to GC analysis by substitution of amine N-H hydrogens with weakly polar moieties such as acyl, silyl, dinitrophenyl and methyl groups [2]. The derivatives of amines generally have much weaker interactions with stationary phases and thus are more volatile in terms of their chromatographic behavior, which leads to better separation on the column. In the last decade base-deactivated columns that give good separations of underivatized aliphatic and aromatic amines have been successfully developed [3]. Consequently, volatile amines in aqueous media can now be routinely and reproducibly analyzed by the combination of SPME(solid- phase microextraction) techniques with base-deactivated GC columns that have been specifically engineered to directly separate amines(see for example [4]). The great advantage of this analytical method is that it sidesteps derivatization,which invariably entails the loss of amines, especially those that are more volatile, through side reactions and incomplete transfer during isolation and workup. Results and Discussion: An aqueous test solution containing an in-house collection of amines standards, viz. N-ethylaniline (100 ppm), dipropylamine (100 ppm), methylamine (100 ppm) and piperidine (100 ppm) was prepared in 80 mL of Millipore water. The majority of this solution (70 mL) was set aside for SPME-GC(CP Volamine)MS analysis while the remaining 10 mL was adjusted to ca. pH = 2 using concentrated HCl to convert all of the amines into their corresponding, non-volatile ammonium salts. The water from this acidified mixture was removed on a rotary evaporator , affording a colourless residue. The solid was dissolved in ca. 3 mL of Millipore water and the pH was brought up to 8 by adding ca. 1 mL of 8 M NaOH(aq). The SPME –GC(CP-Volamine) trace of the reconstituted amine mixture was found to contain the same four amine standards as were seen in solution prior to the protonation step. Thus, this result proves that our amine to ammonium to amine methodologycan be used for the direct determination of volatile alkyl amines and aromatic amines. Application of our new SPME-GC(CP-Volamine)MS method to an aqueous extract of a 2-gram sample of the Tagish Lake stone10a afforded a GC trace that contained three different polar aromatic compounds, namely acetophenone , 4-phenylpyridine and 2-phenyl-1,2-propane diol. In the absence of any isotope ratio data, we cannot conclude whether these three aromatic species are indigenous or terrestrial contaminants. It should be pointed out, however, that acetophenone, has been liberated from the Tagish Lake meteorite by the application of heat [5], and thus it does not seem unreasonable to conclude that the acetophenone seen in the trace for 10a likely has an extraterrestrial origin. References: [1] M.A. Sephton, Astronomy and Geophysics, Vol. 45(2), p. 2.8-2.14 (2004). [2] H. Kataoka, Journal of Chromatography A, 733 (1996) 19-34. [3] "An Advanced Base Deactivated Capillary Column for analysis of Volatile amines, Ammonia and Alcohols.", Jaap de Zeeuw, Ron Stricek and Gary Stidsen, Restek Corp. Bellefonte, USA. [4] L. Muller, E. Fattore and E. Benfenati, Journal of Chromatography A, 791 (1997), 221-230. [5] H. Yabuta, G.D. Cody and C.M.O.D. Alexander (2007). Abstract # 2304, 38th Lunar and Planetary Science Conference.
- ItemNew insights into the heterogeneity of the Tagish Lake meteorite: soluble organic compositions of variously altered specimens(2019) Simkus, Danielle N.; Aponte, José C.; Elsila, Jamie E.; Hilts, Robert; McLain, Hannah L.; Herd, Christopher D. K.The Tagish Lake carbonaceous chondrite exhibits a unique compositional heterogeneity that may be attributed to varying degrees of aqueous alteration within the parent body asteroid. Previous analyses of soluble organic compounds from four Tagish Lake meteorite specimens (TL5b, TL11h, TL11i, TL11v) identified distinct distributions and isotopic compositions that appeared to be linked to their degree of parent body processing (Herd et al. 2011; Glavin et al. 2012; Hilts et al. 2014). In the present study, we build upon these initial observations and evaluate the molecular distribution of amino acids, aldehydes and ketones, monocarboxylic acids, and aliphatic and aromatic hydrocarbons, including compound‐specific δ13C compositions, for three additional Tagish Lake specimens: TL1, TL4, and TL10a. TL1 contains relatively high abundances of soluble organics and appears to be a moderately altered specimen, similar to the previously analyzed TL5b and TL11h lithologies. In contrast, specimens TL4 and TL10a both contain relatively low abundances of all of the soluble organic compound classes measured, similar to TL11i and TL11v. The organic‐depleted composition of TL4 appears to have resulted from a relatively low degree of parent body aqueous alteration. In the case of TL10a, some unusual properties (e.g., the lack of detection of intrinsic monocarboxylic acids and aliphatic and aromatic hydrocarbons) suggest that it has experienced extensive alteration and/or a distinct organic‐depleted alteration history. Collectively, these varying compositions provide valuable new insights into the relationships between asteroidal aqueous alteration and the synthesis and preservation of soluble organic compounds.
- ItemOrigin and evolution of prebiotic organic matter as inferred from the Tagish Lake meteorite(2011) Hilts, Robert; Herd, Christopher D. K.; Blinova, Alexanda; Simkus, Danielle N.; Huang, Yongsong; Tarozo, Rafael; Alexander, Conel M. O.; Gyngard, Frank; Nittler, Larry R.; Cody, George D.; Fogel, Marilyn L.; Kebukawa, Yoko; Kilcoyne, A. L. DavidThe complex suite of organic materials in carbonaceous chondrite meteorites probably originally formed in the interstellar medium and/or the solar protoplanetary disk, but was subsequently modified in the meteorites’ asteroidal parent bodies. The mechanisms of formation and modification are still very poorly understood. We carried out a systematic study of variations in the mineralogy, petrology, and soluble and insoluble organic matter in distinct fragments of the Tagish Lake meteorite. The variations correlate with indicators of parent body aqueous alteration. At least some molecules of prebiotic importance formed during the alteration.
- ItemSoluble organic compounds in the Tagish Lake meteorite(2014) Hilts, Robert; Herd, Christopher D. K.; Simkus, Danielle N.; Slater, Greg F.The C2 ungrouped Tagish Lake meteorite preserves a range of lithologies, reflecting variable degrees of parent-body aqueous alteration. Here, we report on soluble organic compounds, including aliphatic and aromatic hydrocarbons, monocarboxylic acids, and amino acids, found within specimens representative of the range of aqueous alteration. We find that differences in soluble organic compounds among the lithologies may be explained by oxidative, fluid-assisted alteration, primarily involving the derivation of soluble organic compounds from macromolecular material. In contrast, amino acids probably evolved from precursor molecules, albeit in parallel with other soluble organic compounds. Our results demonstrate the role of parent-body alteration in the modification of organic matter and generation of prebiotic compounds in the early solar system, and have implications for interpretation of the complement of soluble organic compounds in carbonaceous chondrites.
- ItemSoluble organic compounds in the Tagish Lake Meteorite(2014) Hilts, Robert; Herd, Christopher D. K.; Simkus, Danielle N.; Slater, Greg F.The C2 ungrouped Tagish Lake meteorite preserves a range of lithologies reflecting variable degrees of parent body aqueous alteration. Here we report on soluble organic compounds, including aliphatic and aromatic hydrocarbons, monocarboxylic acids and amino acids, found within specimens representative of the range of aqueous alteration. We find that differences in soluble organic compounds among the lithologies may be explained by oxidative, fluid-assisted alteration, involving changes from one type of soluble organic compound to another, or derivation of soluble organic compounds from macromolecular material. Our results demonstrate the role of parent body alteration in the modification of organic matter in the early Solar System, and have implications for interpretation of the complement of soluble organic compounds in carbonaceous chondrites.
- ItemSynthesis of prebiotic organic compounds within the Tagish Lake Meteorite(2014) Hilts, Robert; Herd, Christopher D. K.; Simkus, Danielle N.; Slater, Greg F.The Tagish Lake meteorite stones are composites of several different lithologies that exhibit varying degrees of parent body hydrothermal alteration. Through leeching regimens with polar and weakly polar solvents , and by employing GC-MS techniques, we found within the extracts several different classes of soluble organic compounds, ranging from highly polar monocarboxylic acids, amino acids and phenols, to essentially non-polar aliphatic and aromatic hydrocarbons. The differences in both the concentrations and the classes of soluble polar organic species across the four lithologies studied are likely the result of varying degrees of oxidative hydrothermal alteration of primordial insoluble organic matter (IOM).The amino acids found in the water extracts, by contrast, are probably derived from small precursor molecules ,such as aldehydes and ketones, via aqueous-based reactions within the parent body.