Isotope‐ratio detection for gas chromatography

Sessions, Alex L.

doi:10.1002/jssc.200600002

Cited by 244 publications

(288 citation statements)

References 90 publications

(139 reference statements)

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“…, 2002, 2006. However, the data presented in CHAPTER 5 only represent a snapshot in time and considerable time series studies must be conducted before such hypotheses can be validated.…”

Section: Discussionmentioning

confidence: 99%

“…The trends presented by SHERWOOD LOLLAR et al (2002, 2006, 2008 have not been observed in purported abiogenic hydrocarbons from higher temperature settings (Figure 4.8), such as those present in vent fluids of the Lost City hydrothermal site or those formed in abiotic synthesis experiments (FU et al, 2007), leading to speculation that this reflects mechanistic differences. Based on the experimental observations of reversible exchange presented here, this discrepancy may actually reflect partial or complete alkane-water H isotope exchange in the latter cases.…”

Section: H / 1 H Ratios and Abiogenesis In Igneous Environmentsmentioning

confidence: 98%

“…Compound-specific stable hydrogen isotope ( 1 H and 2 H) measurements of carbon-bound hydrogen (TOBIAS and BRENNA, 1997;BURGOYNE and HAYES, 1998;HILKERT et al, 1999;SESSIONS, 2006) have recently become widespread in organic geochemistry. The hydrogen isotope composition of n-alkanes have been utilized to elucidate such diverse processes as abiogenic hydrocarbon formation (SHERWOOD LOLLAR et al, 2002;FU et al, 2007;, formation and biodegradation of petroleum constituents (SCHOELL, 1983;WHITICAR et al, 1985;TANG et al, 2005;SCHIMMELMANN et al, 2006;BOREHAM et al, 2008) and paleoenvironmental changes (SCHEFUSS et al, 2005;SACHSE et al, 2006;EGLINTON and EGLINTON, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Reeves¹

2010

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This thesis presents the results of four discrete investigations into processes governing the organic and inorganic chemical composition of seafloor hydrothermal fluids in a variety of geologic settings. Though Chapters 2 through 5 of this thesis are disparate in focus, each represents a novel investigation aimed at furthering our understanding of subsurface geochemical processes affecting hydrothermal fluid compositions. Chapters 2 and 3 concern the abiotic (nonbiological) formation of organic compounds in high temperature vent fluids, a process which has direct implications for the emergence of life in early Earth settings and sustainment of present day microbial populations in hydrothermal environments. Chapter 2 represents an experimental investigation of methane (CH 4 ) formation under hydrothermal conditions. The overall reduction of carbon dioxide (CO 2 ) to CH 4 , previously assumed to be kinetically inhibited in the absence of mineral catalysts, is shown to proceed on timescales pertinent to crustal residence times of hydrothermal fluids. In Chapter 3, the abundance of methanethiol (CH 3 SH), considered to be a crucial precursor for the emergence of primitive chemoautotrophic life, is characterized in vent fluids from ultramafic-, basalt-and sediment-hosted hydrothermal systems. Previous assumptions that CH 3 SH forms by reduction of CO 2 are not supported by the observed distribution in natural systems. Chapter 4 investigates factors regulating the hydrogen isotope composition of hydrocarbons under hydrothermal conditions. Isotopic exchange between low molecular weight n-alkanes and water is shown to be facilitated by metastable equilibrium reactions between alkanes and their corresponding alkenes, which are feasible in natural systems. In Chapter 5, the controls on vent fluid composition in a backarc hydrothermal system are investigated. A comprehensive survey of the inorganic geochemistry of fluids from sites of hydrothermal activity in the eastern Manus Basin indicates that fluids there are influenced by input of acidic magmatic solutions at depth, and subsequently modified by variable extents of seawater entrainment and mixing-related secondary acidity production. CHAPTER 1 IntroductionSeafloor hydrothermal systems associated with the generation of oceanic crust represent a dramatic expression of heat and mass transfer from the interior of the Earth. In addition to profound effects on ocean chemistry, convective circulation of seawater through volcanically active oceanic crust leads to the formation of metal sulfide deposits. In addition, seafloor hot springs are often invoked as ideal settings from which early microbial life could have emerged.Since the initial discovery of low temperature venting at the Galápagos Spreading Center in 1977 (CORLISS et al., 1979), our understanding of the composition and diversity of hydrothermal solutions has expanded greatly. During convection through oceanic crust of basaltic composition, O 2 -replete seawater reacts with crustal rock, typically producin...

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“…, 2002, 2006. However, the data presented in CHAPTER 5 only represent a snapshot in time and considerable time series studies must be conducted before such hypotheses can be validated.…”

Section: Discussionmentioning

confidence: 99%

Section: H / 1 H Ratios and Abiogenesis In Igneous Environmentsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Reeves¹

2010

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“…Consequently, high-precision isotope ratios have a special place in chemistry, especially in geochemistry, for determining reaction mechanisms and providing formation histories (1). Currently, the most commonly used instruments for determining high-precision isotope ratios are special-purpose isotope-ratio mass spectrometers (IRMS) (2,3) that are fairly costly, require experts to operate and maintain, and are not portable-facts that have limited significantly the applicability of light stable isotope ratio measurements despite the technological advances achieved with online sample introduction and combustion for compound-specific isotope analysis (CSIA) (4).…”

mentioning

confidence: 99%

High-precision optical measurements of ¹³ C/ ¹² C isotope ratios in organic compounds at natural abundance

Zare

Kuramoto

Haase

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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A continuous-flow cavity ring-down spectroscopy (CRDS) system integrating a chromatographic separation technique, a catalytic combustor, and an isotopic 13 C/ 12 C optical analyzer is described for the isotopic analysis of a mixture of organic compounds. A demonstration of its potential is made for the geochemically important class of short-chain hydrocarbons. The system proved to be linear over a 3-fold injection volume dynamic range with an average precision of 0.95‰ and 0.67‰ for ethane and propane, respectively. The calibrated accuracy for methane, ethane, and propane is within 3‰ of the values determined using isotope ratio mass spectrometry (IRMS), which is the current method of choice for compound-specific isotope analysis. With anticipated improvements, the low-cost, portable, and easy-to-use CRDS-based instrumental setup is poised to evolve into a credible challenge to the high-cost and complex IRMS-based technique.cavity ring-down spectroscopy ͉ combustion ͉ isotopic ratio

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“…Generally, the shotnoise ratio is larger for N 2 O than for CO 2 due to the lower abundances of the rare isotope (1.1 % 13 C, 0.37 % 15 N and 0.201 % 18 O, e.g. Sessions, 2006) and the signal intensity of N 2 O as compared to CH 4 -induced CO 2 , due to lower mixing ratios (e.g. Schilt et al, 2010) and ionization efficiency (Friedli and Siegenthaler, 1988;Ghosh and Brand, 2004).…”

Section: Shot Noisementioning

confidence: 99%

An automated GC-C-GC-IRMS setup to measure palaeoatmospheric δ13C-CH4, δ15N-N2O and δ18O-N2O in one ice core sample

et al. 2013

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Abstract. Air bubbles in ice core samples represent the only opportunity to study the mixing ratio and isotopic variability of palaeoatmospheric CH4 and N2O. The highest possible precision in isotope measurements is required to maximize the resolving power for CH4 and N2O sink and source reconstructions. We present a new setup to measure δ13C-CH4, δ15N-N2O and δ18O-N2O isotope ratios in one ice core sample and with one single IRMS instrument, with a precision of 0.09, 0.6 and 0.7‰, respectively, as determined on 0.6–1.6 nmol CH4 and 0.25–0.6 nmol N2O. The isotope ratios are referenced to the VPDB scale (δ13C-CH4), the N2-air scale (δ15N-N2O) and the VSMOW scale (δ18O-N2O). Ice core samples of 200–500 g are melted while the air is constantly extracted to minimize gas dissolution. A helium carrier gas flow transports the sample through the analytical system. We introduce a new gold catalyst to oxidize CO to CO2 in the air sample. CH4 and N2O are then separated from N2, O2, Ar and CO2 before they get pre-concentrated and separated by gas chromatography. A combustion unit is required for δ13C-CH4 analysis, which is equipped with a constant oxygen supply as well as a post-combustion trap and a post-combustion GC column (GC-C-GC-IRMS). The post-combustion trap and the second GC column in the GC-C-GC-IRMS combination prevent Kr and N2O interferences during the isotopic analysis of CH4-derived CO2. These steps increase the time for δ13C-CH4 measurements, which is used to measure δ15N-N2O and δ18O-N2O first and then δ13C-CH4. The analytical time is adjusted to ensure stable conditions in the ion source before each sample gas enters the IRMS, thereby improving the precision achieved for measurements of CH4 and N2O on the same IRMS. The precision of our measurements is comparable to or better than that of recently published systems. Our setup is calibrated by analysing multiple reference gases that were injected over bubble-free ice samples. We show that our measurements of δ13C-CH4 in ice core samples are generally in good agreement with previously published data after the latter have been corrected for krypton interferences.

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Isotope‐ratio detection for gas chromatography

Cited by 244 publications

References 90 publications

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

High-precision optical measurements of ¹³ C/ ¹² C isotope ratios in organic compounds at natural abundance

An automated GC-C-GC-IRMS setup to measure palaeoatmospheric δ<sup>13</sup>C-CH<sub>4</sub>, δ<sup>15</sup>N-N<sub>2</sub>O and δ<sup>18</sup>O-N<sub>2</sub>O in one ice core sample

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Isotope‐ratio detection for gas chromatography

Cited by 244 publications

References 90 publications

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

High-precision optical measurements of 13 C/ 12 C isotope ratios in organic compounds at natural abundance

An automated GC-C-GC-IRMS setup to measure palaeoatmospheric δ&lt;sup&gt;13&lt;/sup&gt;C-CH&lt;sub&gt;4&lt;/sub&gt;, δ&lt;sup&gt;15&lt;/sup&gt;N-N&lt;sub&gt;2&lt;/sub&gt;O and δ&lt;sup&gt;18&lt;/sup&gt;O-N&lt;sub&gt;2&lt;/sub&gt;O in one ice core sample

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Resources

About

High-precision optical measurements of ¹³ C/ ¹² C isotope ratios in organic compounds at natural abundance

An automated GC-C-GC-IRMS setup to measure palaeoatmospheric δ<sup>13</sup>C-CH<sub>4</sub>, δ<sup>15</sup>N-N<sub>2</sub>O and δ<sup>18</sup>O-N<sub>2</sub>O in one ice core sample