Department of Physical Sciences
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Item 11,000 yrs of environmental change in the Northwest Passage; a multiproxy core record from central Parry Channel, Canadian High Arctic(2013) Pieńkowski, Anna J.; England, John H.; Furze, Mark F.A.; Blasco, Steve; Mudie, Peta J.; MacLean, Briana rare paleoenvironmental archive from the understudied west-central Canadian Arctic Archipelago. Lithological, biogeochemical, and microfossil (dinoflagellate cysts, non-pollen palynomorphs, benthic and planktonic foraminifera) characteristics, in combination with a chronostratigraphy based on seventeen radiocarbon dates, show seven prominent paleoenvironmental episodes since the end of the last regional glaciation. The basal diamict (Zone I) records decoupling of previously grounded glacial ice, followed by ice-proximal conditions (Zone IIa) commencing at ~ 10.8 cal ka BP (age-depth model extrapolation). After an interval of pervasive sea-ice (Zone IIb), ice-distal conditions are established (Zone IIc). Although sparse microfossils are present in glaciomarine sediments (Zone II), noticeable biological activity with heightened abundances and diversities across all groups begins in the postglacial Zone III (10.3–10.0 cal ka BP) when planktonic foraminifera (Neogloboquadrina pachyderma) appear. As planktonics are excluded from the study area today (due to shallow inter-channel sills), this likely signals the inflow of relatively warm and saline Atlantic-derived Arctic Intermediate Water below 250 m, presumably facilitated by glacio-isostatically enhanced deglacial water depths. The subsequent Zone IV (10.0–7.0 cal ka BP), characterized by heightened biological productivity in both plankton and benthos and reduced seasonal sea-ice cover, may correspond to a previously proposed Holocene Thermal Maximum. This apparent amelioration ends by the mid Holocene (Zone V; 7.0–5.7 cal ka BP) when Arctic Intermediate Water is excluded from the study area and water depths approach modern values. High-Arctic conditions with seasonal sea-ice cover, a circulation dominated by Arctic Ocean Surface Water, and microfossil assemblages similar to modern are found from ~ 5.7 cal ka BP onwards (Zones VI–VII). As only minor environmental fluctuations are apparent during the late Holocene, shorter-term climatic episodes (e.g. Little Ice Age) are not recognized in this record.Item Absorption of electromagnetic waves in sandstone saturated with brine and nanofluids for application in enhanced oil recovery(2019) Ali, Hassan; Soleimani, Hassan; Yahya, Noorhana; Lorimer, Shelley; Sabet, Maziyar; Demiral, Birol M. R.; Adebayo, Lawal LanreIn this study, scattering parameters of sandstone saturated with brine and nanofluids are evaluated experimentally and numerically for the application in enhanced oil recovery (EOR). Zinc Oxide (ZnO) and Bismuth ferrite BiFeO3 (BFO) nanoparticles were synthesized via facile sol–gel method followed by nanofluid preparation. Sandstone samples were saturated with brine and nanofluids for 48 h. Electromagnetic properties of the saturated sandstones were measured experimentally using the vector network analyzer, and the scattering parameters of the samples were studied numerically by finite element method. BFO displayed higher permeability value of 1.52 and 1.30, as well as superior dielectric permittivity value 11.55 and 6.59 for real and imaginary parts, respectively. In addition, the sandstone saturated with BFO showed an impressive reflection loss (RL) value of −9.77 dB at high frequency. Conclusively, BiFeO3 nanofluids showed the best potential to enhance oil recovery which can be accredited to the superior electromagnetic properties of BFO.Item Adjustable methacrylate porous monolith polymer layer open tubular silica capillary microextraction for the determination of polycyclic aromatic hydrocarbons(2016) Mugo, Samuel; Huybregts, Lauren; Mazurok, JamesA novel adjustable porous polymer monolith layer open tubular silica capillary microextraction (PLOT-ME) device was fabricated by thermal polymerization of a poly(glycidylmethacrylate-co-ethylene glycol dimethacrylate) (GMA-co-EDMA) polymer film (∼20 µm) within a 250 µm internal diameter silica capillary initiated with 4,4′-azobis(4-cyanopentanoyl chloride). The polymer film thickness and morphology were controlled by the polymerization time and temperature. The length of the microextraction platform immersed in the sample was adjusted by the sample concentration and sample matrix. Furthermore, since the microextraction platform performance typically degraded with use, the PLOT-ME device affords a new microextraction zone that may be exposed by cleaving off the end. This ability significantly reduces the cost of microextraction for academic and research environments. The performance of the PLOT-ME device was tested for microextraction of polycyclic aromatic hydrocarbons (PAHs): naphthalene, 2,6-dimethylnaphthalene, anthracene, 9-methylanthracene, and phenanthrene in aqueous media. Linear calibration curves for the PAHs were obtained with correlation coefficients near unity and relative standard deviations from 2 to 20% for PAH standards from 100 to 0.1 µg/L. The limits of detection for the PAHs were between 0.02 and 0.06 µg/L, while the recoveries were from 97 to 104% in lake water. The precision between different PLOT-ME devices was 11%.Item Adsorption of selected heavy metals on modified nano cellulose(2016) Madivoli, Edwin S.; Kareru, Patrick G.; Gachanja, Anthony N.; Mugo, Samuel; Murigi, Martin K.; Kairigo, P. K.; Kipyegon, Cheruiyot; Mutembei, Jackson K.; Njonge, Francis K.Cellulose is an inexpensive, renewable, bio-based and an abundant raw material suitable for the development of filter membranes for water purification. This is because it has numerous functional groups that afford ease of modification to create active surfaces upon chemical modification. In this study, cellulose was isolated from two abundant biomasses, namely, Eichhornia crassipes and Cyperus papyrus using the soda process followed by bleaching with peracetic acid. The percent yield of cellulose nanofibrils (CNF) obtained from E. crassipes and C. papyrus was found to be 31.64 ± 1.46% and 29.55 ± 0.64% respectively. The degree of crystallinity and crystal sizes were calculated to be 71.42% and 0.059 nm for E. crassipes and 46.15% and 0.068 nm for C. papyrus respectively. The FT-IR absorption of the carbonyl functional group of an ester indicated that effective esterification of cellulose using citric acid was obtained when cellulose nanofibrils to citric acid ratio was 1:1. From batch adsorption studies, the capacity for citric acid modified cellulose to remove heavy metals was determined to be 8.36 mg/g Zn2+, 18.06 mg/g Cu2+, 42.69 mg/g Cd2+ and 21.64 mg/g Pb2+. In comparison to the % adsorption using unmodified cellulose of less than 5%, the heavy metals adsorption using modified nanocellulose materials were 86.47% Pb2+, 85.20% Cd2+, 77.40% Cu2+, and 70.04% Zn2+. From these results, it was concluded that modified cellulose could be used as a low cost adsorbent for removal of heavy metals and that development of household water filtration units using modified cellulose could be exploited.Item Affinity crystallography: a new approach to extracting high-affinity enzyme inhibitors from natural extracts(2016) Aguda, Adeleke H.; Lavallee, Vincent; Cheng, Ping; Bott, Tina; Meimetis, Labros G.; Law, Simon; Nguyen, Nham T.; Williams, David E.; Kaleta, Jadwiga; Villanueva, Ivan; Davies, Julian; Andersen, Raymond J.; Brayer, Gary D.; Brömme, DieterNatural products are an important source of novel drug scaffolds. The highly variable and unpredictable timelines associated with isolating novel compounds and elucidating their structures have led to the demise of exploring natural product extract libraries in drug discovery programs. Here we introduce affinity crystallography as a new methodology that significantly shortens the time of the hit to active structure cycle in bioactive natural product discovery research. This affinity crystallography approach is illustrated by using semipure fractions of an actinomycetes culture extract to isolate and identify a cathepsin K inhibitor and to compare the outcome with the traditional assay-guided purification/structural analysis approach. The traditional approach resulted in the identification of the known inhibitor antipain (1) and its new but lower potency dehydration product 2, while the affinity crystallography approach led to the identification of a new high-affinity inhibitor named lichostatinal (3). The structure and potency of lichostatinal (3) was verified by total synthesis and kinetic characterization. To the best of our knowledge, this is the first example of isolating and characterizing a potent enzyme inhibitor from a partially purified crude natural product extract using a protein crystallographic approach.Item All wired up: an exploration of the electrical properties of microtubules and tubulin(2020) Kalra, Aarat P.; Eakins, Boden B.; Patel, Sahil D.; Ciniero, Gloria; Rezania, Vahid; Shankar, Karthik; Tuszynski, Jack A.Microtubules are hollow, cylindrical polymers of the protein α, β tubulin, that interact mechanochemically with a variety of macromolecules. Due to their mechanically robust nature, microtubules have gained attention as tracks for precisely directed transport of nanomaterials within lab-on-a-chip devices. Primarily due to the unusually negative tail-like C-termini of tubulin, recent work demonstrates that these biopolymers are also involved in a broad spectrum of intracellular electrical signaling. Microtubules and their electrostatic properties are discussed in this Review, followed by an evaluation of how these biopolymers respond mechanically to electrical stimuli, through microtubule migration, electrorotation and C-termini conformation changes. Literature focusing on how microtubules act as nanowires capable of intracellular ionic transport, charge storage, and ionic signal amplification is reviewed, illustrating how these biopolymers attenuate ionic movement in response to electrical stimuli. The Review ends with a discussion on the important questions, challenges, and future opportunities for intracellular microtubule-based electrical signaling.Item Altitudinal variability of monsoon precipitation over mountainous region(2004) Singh, Prasamsa; Prajapati, Shiva BhaktaThe study conducted some investigations to know the relationship between topographic effects on rainfall distribution with regards to the topographic elevation over Mountainous region. Comparison of relationship between topographic effects on rainfall distribution with relation to the topographic elevation using ground based data of one hundred and ninety one rain gauge stations within domain of latitude 27.30' to 29.40' and longitude 80.00' to 84.00' of period June - August (1998- 2000) and Tropical Rainfall Measuring Mission/ Precipitation Radar (TRMM/ PR) within domain latitude 26.00' to 32.00' and longitude 75.00' to 80. 00' of the same duration are characterized relatively well. Digital elevation map (DEM) with spatial resolution 30 sec (Gtopo30) is used for spatial topographic study. Much attention was focused on "effective height for precipitation" i.e. topographic height where amount of rainfall is high. It was found through investigation that the rainfall decreases beyond 1800m using ground based data and rainfall decreases beyond 2100m using TRMM data.Item Analysis of conformational b-cell epitopes in the antibody-antigen complex using the depth function and the convex hull(2015) Zheng, Wei; Ruan, Jishou; Hu, Gang; Wang, Kui; Hanlon, Michelle; Gao, JianzhaoThe prediction of conformational b-cell epitopes plays an important role in immunoinformatics. Several computational methods are proposed on the basis of discrimination determined by the solvent-accessible surface between epitopes and non-epitopes, but the performance of existing methods is far from satisfying. In this paper, depth functions and the k-th surface convex hull are used to analyze epitopes and exposed non-epitopes. On each layer of the protein, we compute relative solvent accessibility and four different types of depth functions, i.e., Chakravarty depth, DPX, half-sphere exposure and half space depth, to analyze the location of epitopes on different layers of the proteins. We found that conformational b-cell epitopes are rich in charged residues Asp, Glu, Lys, Arg, His; aliphatic residues Gly, Pro; non-charged residues Asn, Gln; and aromatic residue Tyr. Conformational bcell epitopes are rich in coils. Conservation of epitopes is not significantly lower than that of exposed non-epitopes. The average depths (obtained by four methods) for epitopes are significantly lower than that of non-epitopes on the surface using the Wilcoxon rank sum test. Epitopes are more likely to be located in the outer layer of the convex hull of a protein. On the benchmark dataset, the cumulate 10th convex hull covers 84.6% of exposed residues on the protein surface area, and nearly 95% of epitope sites. These findings may be helpful in building a predictor for epitopes.Item Anatomy of a young impact crater in Central Alberta: prospects for the ‘missing’ Holocene impact record(2008) Herd, Christopher D. K.; Froese, D. F.; Walton, Erin L.; Herd, E. P. K.; Duke, J.Small impact events recorded on the surface of Earth are significantly underrepresented based on expected magnitude-frequency relations. We report the discovery of a 36-m-diameter late Holocene impact crater located in a forested area near the town of Whitecourt, Alberta, Canada. Although undetectable using visible imagery, the presence of the crater is revealed using a bare-Earth digital elevation model obtained through airborne light detection and ranging (LiDAR). The target material comprises deglacial Quaternary sediments, with impact ejecta burying a late Holocene soil dated to ca. 1100 14C yr B.P. Most of the 74 iron meteorites (0.1–1196 g) recovered have an angular exterior morphology. These meteorites were buried at depths <25 cm and are interpreted to result from fragmentation of the original projectile mass, either at low altitude or during the impact event. Impact of the main mass formed the simple bowl-shaped impact structure associated with an ejecta blanket and crater fill. The increasing availability of LiDAR data for many terrestrial surfaces will serve as a useful tool in the discovery of additional small impact features.Item Antibiotic residues in milk from Juja and Githurai markets in Kenya by liquid chromatography-tandem mass spectrometry(2021) Ouma, Josephine; Gachanja, Anthony N.; Mugo, Samuel; Gikunju, JosephThe use of antibiotics in livestock production can potentially generate drug residues in animal products, leading to adverse health effects for consumers. This study was carried out to assess the presence and quantify the levels of antibiotic residues in milk sold in Juja and Githurai markets in Kenya. A total of 65 milk samples, comprising raw milk purchased from shops (32 samples), milk purchased from automated vending machines (23 samples) and packet milk (10 samples) were analyzed for the presence of amoxicillin, cloxacillin, tetracycline, sulfamethoxazole and trimethoprim residues. A single aqueous extraction was performed and the extracts were analyzed using liquid chromatography-tandem mass spectrometry. The prevalence of antibiotic residues in raw milk samples purchased from shops and milk dispensed from automated vending machines was 46.9% and 26.1%, respectively. No antibiotic residues were detected in packet milk samples. The prevalence of antibiotic residues was higher in milk from Githurai market compared to Juja market (52% vs. 25%, P value = 0.0137). Overall, 10.8% of samples tested positive for at least one antibiotic residue above the maximum residue limits established by the Codex Alimentarius Commission and the European Union, while 20% of samples had detectable antibiotic residues at concentrations below the maximum residue limits. The mean concentrations were 6.7 µg/L, 53.3 µg/L, 30.6 µg/L, 5.0 µg/L and 6.2 µg/L for amoxicillin, cloxacillin, tetracycline, sulfamethoxazole and trimethoprim, respectively. These results suggest frequent occurrence of antibiotic residues in some milk from the selected markets, which may be posing a public health risk to consumers.Item Asymmetric synthesis of (1R,2S,3R)-gamma-methyl-cis-pentacin by a kinetic resolution protocol(2002) Bailey, Simon; Davies, Stephen G.; Smith, Andrew D.; Withey, Jonathan M.The asymmetric synthesis of (1R,2S,3R)-3-methyl-2-amino-cyclopentane carboxylic acid has been achieved via kinetic resolution of racemic tert-butyl 3-methyl-cyclopentene-1-carboxylate with homochiral lithium (S)-N-benzyl-N-alpha-methylbenzylamide.Item Asymmetric synthesis of the cis- and trans-stereoisomers of 4-aminopyrrolidine-3-carboxylic acid and 4-aminotetrahydrofuran-3-carboxylic acid(2004) Bunnage, Mark E.; Davies, Stephen G.; Roberts, Paul M.; Smith, Andrew D.; Withey, Jonathan M.The diastereoselective conjugate addition of lithium (S)-N-benzyl-N-alpha-methylbenzylamide has been successfully applied to the first asymmetric syntheses of cis-(3S,4R)- and trans-(3R,4R)-4-aminotetrahydrofuran-3-carboxylic acids (26% and 25% overall yield respectively, > 98% d.e. and > 97% e. e. in each case). Furthermore, the most efficient asymmetric synthesis to date of cis-( 3R, 4R)- and trans-( 3R, 4S)-4-aminopyrrolidine carboxylic acids is delineated: for cis-( 3R, 4R), four steps, > 98% d.e., 52% overall yield; for trans-( 3R, 4S), five steps, > 98% d.e., 50% overall yield.Item Atlantic water inflow in the early Holocene Northwest Passage marked by planktonic foraminifera (Neogloboquadrina pachyderma)(2015) Pieńkowski, Anna J.; Cage, Alix; Furze, Mark F.A.; Figueiredo Martins, Ana Sílvia de; England, John H.; McLean, Brian; Blasco, SteveFour marine piston cores from the central Canadian Arctic Archipelago (CAA), investigated for sedimentology, micropalaeontology, and biogeochemistry (52 AMS radiocarbon dates), uniformly show the prominent early Holocene (˜10 cal ka BP) appearance of planktonic foraminifera immediately following deglaciation.Item Azide trapping of metallocarbenes: generation of reactive C-acylimines and domino trapping with nucleophiles(2014) Bott, Tina; Atienza, Bren Jordan; West, F. G.Azide-tethered diazocarbonyl compounds undergo copper-catalyzed conversion to transient C-acylimines. These reactive intermediates can be trapped with a variety of carbon nucleophiles, giving rise to complex 3-indolinone frameworks, including those with adjacent tetra-substituted carbon centers, in a single transformation.Item Basin scale evolution of zebra textures in fault-controlled, hydrothermal dolomite bodies: insights from the Western Canadian Sedimentary Basin(2023) McCormick, Cole A.; Corlett, Hilary; Clog, Matthieu; Boyce, Adrian; Tartèse, Romain; Steele-MacInnis, Matthew; Hollis, CathyStructurally controlled dolomitization typically involves the interaction of high-pressure (P), high-temperature (T) fluids with the surrounding host rock. Such reactions are often accompanied by cementation and recrystallization, with the resulting hydrothermal dolomite (HTD) bodies including several ‘diagnostic’ rock textures. Zebra textures, associated with boxwork textures and dolomite breccias, are widely considered to reflect these elevated P/T conditions. Although a range of conceptual models have been proposed to explain the genesis of these rock textures, the processes that control their spatial and temporal evolution are still poorly understood. Through the detailed petrographical and geochemical analysis of HTD bodies, hosted in the Middle Cambrian strata in the Western Canadian Sedimentary Basin, this study demonstrates that a single genetic model cannot be applied to all the characteristics of these rock textures. Instead, a wide array of sedimentological, tectonic and metasomatic processes contribute to their formation; each of which is spatially and temporally variable at the basin scale. Distal to the fluid source, dolomitization is largely stratabound, comprising replacement dolomite, bedding-parallel zebra textures and rare dolomite breccias (non-stratabound, located only proximal to faults). Dolomitization is increasingly non-stratabound with proximity to the fluid source, comprising bedding-inclined zebra textures, boxwork textures and dolomite breccias that have been affected by recrystallization. Petrographical and geochemical evidence suggests that these rock textures were initiated due to dilatational fracturing, brecciation and precipitation of saddle dolomite as a cement, but significant recrystallization occurred during the later stages of dolomitization. These rock textures are closely associated with faults and carbonate-hosted ore deposits (e.g. magnesite, rare earth element and Mississippi Valley–type mineralization), thus providing invaluable information regarding fluid flux and carbonate metasomatism under elevated P/T conditions.Item Building a 3D virtual liver: methods for simulating blood flow and hepatic clearance on 3D structures(2016) White, Diana; Coombe, Dennis; Rezania, Vahid; Tuszynski, Jack A.In this paper, we develop a spatio-temporal modeling approach to describe blood and drug flow, as well as drug uptake and elimination, on an approximation of the liver. Extending on previously developed computational approaches, we generate an approximation of a liver, which consists of a portal and hepatic vein vasculature structure, embedded in the surrounding liver tissue. The vasculature is generated via constrained constructive optimization, and then converted to a spatial grid of a selected grid size. Estimates for surrounding upscaled lobule tissue properties are then presented appropriate to the same grid size. Simulation of fluid flow and drug metabolism (hepatic clearance) are completed using discretized forms of the relevant convective-diffusive-reactive partial differential equations for these processes. This results in a single stage, uniformly consistent method to simulate equations for blood and drug flow, as well as drug metabolism, on a 3D structure representative of a liver.Item Burial dolomitization driven by modified seawater and basal aquifer-sourced brines: Insights from the Middle and Upper Devonian of the Western Canadian Sedimentary Basin(2020) Stacey, Jack; Hollis, Cathy; Corlett, Hilary; Koeshidayatullah, ArdiansyahDolomitization in the Western Canadian Sedimentary Basin has been extensively researched, producing vast geochemical datasets. This provides a unique opportunity to assess the regional sources and flux of dolomitizing fluids on a larger scale than previous studies. A meta-analysis was conducted on stable isotope, strontium isotope (87Sr/86Sr), fluid inclusion and lithium-rich formation water data published over 30 years, with new petrographic, X-ray diffraction, stable isotope and rare-earth element (REE+Y) data. The Middle to Upper Devonian Swan Hills Formation, Leduc Formation and Wabamun Group contain replacement dolomite (RD) cross-cut by stylolites, suggesting replacement dolomitization occurred during shallow burial. Stable isotope, REE+Y and 87Sr/86Sr data indicate RD formed from Devonian seawater, then recrystallized during burial. Apart from the Wabamun Group of the Peace River Arch (PRA), saddle dolomite cement (SDC) is more δ18O(PDB) depleted than RD, and cross-cuts stylolites, suggesting precipitation during deep burial. SDC 87Sr/86Sr data indicate contributions from 87Sr-rich basinal brines in the West Shale Basin (WSB) and PRA, and authigenic quartz/albite suggests basinal brines interacted with underlying clastic aquifers before ascending faults into carbonate strata. The absence of quartz/albite within dolomites of the East Shale Basin (ESB) suggests dolomitizing fluids only interacted with carbonate strata. We conclude that replacement dolomitization resulted from connate Devonian seawater circulating through aquifers and faults during shallow burial. SDC precipitated during deep burial from basinal brines sourced from basal carbonates (ESB) and clastic aquifers (WSB, PRA). Lithium-rich formation waters suggest basinal brines originated as residual evapo-concentrated Middle Devonian seawater that interacted with basal aquifers and ascended faults during the Antler and Laramide Orogenies. These results corroborate those of previous studies but are verified by new integrated analysis of multiple datasets. New insights emphasize the importance of basal aquifers and residual evapo-concentrated seawater in dolomitization, which is potentially applicable to other regionally dolomitized basins.Item Candida antarctica B lipase loaded microreactor for the automated derivatization of lipids(2016) Mugo, Samuel; Tiedemann, KyleA key bottleneck in the profiling of lipids is the multistep derivatization required prior to gas chromatography (GC) analysis. A single in-vial lipid derivatization and analysis may significantly minimize sample loss and improve analytical sensitivity. A cotton fiber supported poly(glycidylmethacrylate-co-ethylene glycol dimethacrylate) polymer microbrush microreactor loaded with Candida antarctica lipase B was developed for the facile conversion of triacylglycerols into fatty acid ethyl ester derivatives for gas chromatograph – mass spectrometry (GC-MS) analysis. The polymer microbrush microreactor was fabricated in effort to provide efficient, simplified, cost-effective, and high throughput GC-MS determination of triacylglycerols. The polymer microbrush microreactor was used as an in-vial triacylglycerol transesterification platform, with economical sample consumption of less than or equal to 100 µL and significant reduction of reagents. To evaluate the polymer microbrush microreactor performance for lipids, a triolein standard and camelina oil triacylglycerols were quantitatively transformed into ethyl oleate and fatty acid ethyl esters, respectively, following a three hour reaction time. The lipase loaded cotton fiber supported poly (glycidylmethacrylate-co-ethylene glycol dimethacrylate) polymer microbrush microreactors were reusable for up to five times for quantitative transesterification with minimal loss of lipase activity.Item Carboxylic acid abundances in the Tagish Lake meteorite: lithological differences and implications for formic acid abundances in carbonaceous chondrites(2009) Hilts, Robert; Herd, Christopher D. K.; Morgan, Don; Edwards, LeAnne; Huang, YongsongThe most abundant soluble organic compounds in carbonaceous chondrites are typically carboxylic acids (Pizzarello et al 2001). Strait-chain monocarboxylic acids up to C-12 have been the focus of considerable attention owing to the exciting possibility that they may have been incorporated into the molecular architecture of prebiotic protomembranes on the ancient Earth (e.g., Silva et al 2004.) The most abundant monocarboxylic acid in interstellar space is formic acid (e.g. Remigen et al. 2003; Snyder 2008). It is generally accepted that the organic material in carbonaceous chondrites such as the Tagish Lake meteorite, which includes carboxylic acids, is derived from interstellar or nebular sources (Cronin et al 1988 and Cronin et al 1993). It is somewhat surprising, therefore, that up until now only what have been described as small or moderate formic acid concentrations have been found in aqueous extracts of carbonaceous chondrites (Huang et al 2005, Naraoka et al 1999, Yuen et al 1973, Shimoyama et al 1986, Yuen et al 1984 and Krishnamurthy et al 1992). Previous reports have ascribed the unexpectedly low formic acid abundances to either compound loss during extraction and subsequent work up, or to depletion caused by evaporation and/or aqueous leaching of the compound from the meteorite upon its exposure to the Earth's hydrosphere (Huang et al 2005 and Naraoka et al 1999). Here we present our analysis of the water-soluble monocarboxylic acids in two different lithologies within the Tagish Lake meteorite using the SPME-GCMS procedures recently developed by Huang et al 2005 to compare the two lithologies in this respect. Our results conclusively show that formic acid is, by a wide margin, the most abundant monocarboxylic acid in both of the Tagish Lake lithologies investigated thus far. This is in stark contrast to all previous studies of other meteorites in which it was concluded that the formic acid concentration was the lowest or one of the lowest of those monocarboxylic acids present in the extract (Huang et al 2005, Naraoka et al 1999, Yuen et al 1973, Shimoyama et al 1986, Yuen et al 1984 and Krishnamurthy et al 1992). Moreover, our serendipitous discovery that formic acid has a very low response factor when run on either GCMS(quadrupole) or GC-FID (Allen et al 1987) instruments suggests that previous studies on carbonaceous chondrites may have dramatically underestimated the quantities of formic acid present. Also, a close inspection of the relative abundances for the straight-chain monocarboxylic acids in each Tagish Lake lithology has led us to conclude that the overall oxidation levels for the water soluble organics from the two lithologies are different. Lastly, we have found that the monocarboxylic acids within the Tagish Lake meteorite are enriched in deuterium compared to terrestrial organics, with delta D values ranging from + 247 to + 581%o. These results confirm that the acids originate from interstellar space and that terrestrial contamination has been largely avoided.Item Carboxylic acid abundances in the Tagish Lake meteorite: lithological differences and implications for formic acid abundances in carbonaceous chondrites(2009) Hilts, Robert; Herd, Christopher D. K.; Morgan, Don; Edwards, LeAnne; Huang, YongsongAnalysis of two different Tagish Lake rocks found: 1) a very low GCMS response for formic acid, 2) formic acid concns above 100 ppm and 3) that formic acid to higher homologue ratios indicate the average level of oxidation for the soluble organics.