The Organic Isotopologue Frontier

Gilbert, Alexis

doi:10.1146/annurev-earth-071420-053134

Cited by 25 publications

(33 citation statements)

References 141 publications

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“…Previous studies have also demonstrated that differences in the bulk and position-specific 13 C isotope composition of propane can be influenced by the source, the rate and temperature of gas formation as well as secondary processes such as migration or diffusion [21,35,36]. A different original source of hydrocarbons is supported by the higher 13 C/ 12 C ratios for methane and ethane in Gamou compared with those in Murono (Table 2).…”

Section: Position-specific 13 C Composition Of Propanementioning

confidence: 77%

“…The past few years have witnessed a boom in hydrocarbon isotopic analysis with the advent of isotopologue analysis. Isotopologues are molecules that differ in the number and/or position of isotope substitution [ 11 , 12 ]. These include multiply substituted isotope species such as 13 C H 3 D and CH 2 D 2 for methane [ 13 , 14 , 15 , 16 ], 13 C H 3 - 13 C H 3 for ethane [ 17 , 18 ], as well as position-specific isotopologues such as 13 C H 3 -CH 2 -CH 3 and CH 3 - 13 C H 2 CH 3 of propane [ 19 , 20 , 21 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

“…The latter approach has proven particularly useful for the detection of hydrocarbon anaerobic oxidation in natural gas basins [23]. Through culture experiments using sulfate-reducing bacteria isolated from the Guaymas Basin [24], Gilbert et al [23] showed that bacteria tend to assimilate the central 13 C-isotopologue of propane at a lower rate compared with the terminal 13 C-isotopologue and the 12 C-isotopologue. The relative 13 C-enrichment depends on the extent of anaerobic oxidation of propane and has been used to detect and quantify biodegradation of propane in natural gas reservoirs [12,23].…”

Section: Introductionmentioning

confidence: 99%

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Hydrocarbon Cycling in the Tokamachi Mud Volcano (Japan): Insights from Isotopologue and Metataxonomic Analyses

et al. 2022

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Understanding hydrocarbon cycling in the subsurface is important in various disciplines including climate science, energy resources and astrobiology. Mud volcanoes provide insights into biogeochemical processes occurring in the subsurface. They are usually associated with natural gas reservoirs consisting mainly of methane and other hydrocarbons as well as CO2. Stable isotopes have been used to decipher the sources and sinks of hydrocarbons in the subsurface, although the interpretation can be ambiguous due to the numerous processes involved. Here we report new data for hydrocarbon isotope analysis, including position-specific isotope composition of propane, for samples from the Tokamachi mud volcano area, Japan. The data suggest that C2+ hydrocarbons are being biodegraded, with indirect production of methane (“secondary methanogenesis”). Data from chemical and isotopic composition are discussed with regard to 16S rRNA analysis, which exhibits the presence of hydrogenotrophic and acetoclastic methoanogens. Overall, the combination of isotopologue analysis with 16S rRNA gene data allows refining of our understanding of hydrocarbon cycling in subsurface environments.

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Section: Position-specific 13 C Composition Of Propanementioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydrocarbon Cycling in the Tokamachi Mud Volcano (Japan): Insights from Isotopologue and Metataxonomic Analyses

et al. 2022

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“…Amino acid PSIA has been achieved previously by a range of methodologies, including isotopic nuclear magnetic resonance (NMR) spectroscopy of intact molecules, and IRMS coupled to online or offline chemical and/or thermal degradation (for reviews, see Refs [20][21][22] ). Most prior amino acid PSIA studies have targeted pre-purified analytes, purchased commerciallyreflecting the challenges of isolating amino acids from natural samples in large enough quantities or with sufficient purity for existing measurement strategies.…”

Section: Intramolecular Carbon Isotope Fractionations Have Been Observedmentioning

confidence: 99%

Position‐specific carbon isotope analysis of serine by gas chromatography/Orbitrap mass spectrometry, and an application to plant metabolism

Wilkes

Sessions

Zeichner

et al. 2022

Rapid Comm Mass Spectrometry

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Rationale Position‐specific 13C/12C ratios within amino acids remain largely unexplored in environmental samples due to methodological limitations. We hypothesized that natural‐abundance isotope patterns in serine may serve as a proxy for plant metabolic fluxes including photorespiration. Here we describe an Orbitrap method optimized for the position‐specific carbon isotope analysis of serine to test our hypothesis and discuss the generalizability of this method to other amino acids. Methods Position‐specific carbon isotope ratios of serine were measured using a Thermo Scientific™ Q Exactive™ GC Orbitrap™. Amino acids were hydrolyzed from Arabidopsis biomass, purified from potential matrix interferences, and derivatized alongside standards. Derivatized serine (N,O‐bis(trifluoroacetyl)methyl ester) was isolated using gas chromatography, trapped in a reservoir, and purged into the electron ionization source over tens of minutes, producing fragment ions containing different combinations of atoms from the serine‐derivative molecule. The 13C/12C ratios of fragments with monoisotopic masses of 110.0217, 138.0166, and 165.0037 Da were monitored in the mass analyzer and used to calculate position‐specific δ13C values relative to a working standard. Results This methodology constrains position‐specific δ13C values for nanomole amounts of serine isolated from chemically complex mixtures. The δ13C values of fragment ions of serine were characterized with ≤1‰ precisions, leading to propagated standard errors of 0.7–5‰ for each carbon position. Position‐specific δ13C values differed by up to ca 28 ± 5‰ between serine molecules hydrolyzed from plants grown under contrasting pCO2, selected to promote different fluxes through photosynthesis and photorespiration. The method was validated using pure serine standards characterized offline. Conclusions This study presents the first Orbitrap‐based measurements of natural‐abundance, position‐specific carbon isotope variation in an amino acid isolated from a biological matrix. We present a method for the precise characterization of isotope ratios in serine and propose applications probing metabolism in plants. We discuss the potential for extending these approaches to other amino acids, paving the way for novel applications.

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“…Both approaches involve laboratory-based instrumentation, and the samples are unavoidably destroyed either before (e.g., pyrolisis) or during analysis. Nevertheless, they were successfully applied to measure the intramolecular 13 C distribution of natural gas samples of thermogenic origin. − These pioneering studies revealed that thermogenic propane exhibits systematic variations in the carbon isotope structure. However, more detailed research and widespread applications are required to better understand the various processes and pathways that occur in natural gas systems.…”

Section: Introductionmentioning

confidence: 99%

Position-Specific Isotope Analysis of Propane by Mid-IR Laser Absorption Spectroscopy

et al. 2023

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Intramolecular or position-specific carbon isotope a n a l y s i s o f p r o p a n e ( 1 3 C H 3 − 1 2 C H 2 − 1 2 C H 3 a n d 12 CH 3 − 13 CH 2 − 12 CH 3 ) provides unique insights into its formation mechanism and temperature history. The unambiguous detection of such carbon isotopic distributions with currently established methods is challenging due to the complexity of the technique and the tedious sample preparation. We present a direct and nondestructive analytical technique to quantify the two singly substituted, terminal ( 13 C t ) and central ( 13 C c ), propane isotopomers, based on quantum cascade laser absorption spectroscopy. The required spectral information on the propane isotopomers was first obtained using a high-resolution Fourier-transform infrared (FTIR) spectrometer and then used to select suitable mid-infrared regions with minimal spectral interference to obtain the optimum sensitivity and selectivity. We then measured high-resolution spectra around 1384 cm −1 of both singly substituted isotopomers by mid-IR quantum cascade laser absorption spectroscopy using a Stirling-cooled segmented circular multipass cell (SC-MPC). The spectra of the pure propane isotopomers were acquired at both 300 and 155 K and served as spectral templates to quantify samples with different levels of 13 C at the central (c) and terminal (t) positions. A prerequisite for the precision using this reference template fitting method is a good match of amount fraction and pressure between the sample and templates. For samples at natural abundance, we achieved a precision of 0.33 ‰ for δ 13 C t and 0.73 ‰ for δ 13 C c values within 100 s integration time. This is the first demonstration of sitespecific high-precision measurements of isotopically substituted non-methane hydrocarbons using laser absorption spectroscopy. The versatility of this analytical approach may open up new opportunities for the study of isotopic distribution of other organic compounds.

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The Organic Isotopologue Frontier

Cited by 25 publications

References 141 publications

Hydrocarbon Cycling in the Tokamachi Mud Volcano (Japan): Insights from Isotopologue and Metataxonomic Analyses

Hydrocarbon Cycling in the Tokamachi Mud Volcano (Japan): Insights from Isotopologue and Metataxonomic Analyses

Position‐specific carbon isotope analysis of serine by gas chromatography/Orbitrap mass spectrometry, and an application to plant metabolism

Position-Specific Isotope Analysis of Propane by Mid-IR Laser Absorption Spectroscopy

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