Molecular and isotopic analysis of oils by solid phase microextraction of gasoline range hydrocarbons

Harris, Scott A.; Whiticar, Michael J.; Eek, Magnus K

doi:10.1016/s0146-6380(99)00056-x

Cited by 41 publications

(42 citation statements)

References 19 publications

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“…Surprisingly, high-resolution chromatographic columns will (partially) separate molecules containing just one D atom from those containing none, as well as those containing one 13 C, 15 N, etc. This is true even for C 40 hydrocarbons and above, where the mass difference between singly substituted isotopologs is only 0.2%. The difference in retention time is only fractions of a second, but the inevitable result is that each chromatographic peak is isotopically inhomogeneous in the time domain [44,45].…”

Section: Peak Resolutionmentioning

confidence: 93%

“…Injection of volatile organic compounds (VOCs) is more difficult because of associated evaporative fractionations. Harris et al [40] compared purge-and-trap and headspace SPME methods for 13 C analysis of gasoline-range hydrocarbons, and concluded that both methods can yield accurate and precise results if injection conditions are carefully optimized. Dayan et al [41] used headspace SPME to measure 13 C in chlorinated solvents, and observed a consistent 0.3?…”

Section: Injection Methodsmentioning

confidence: 99%

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Isotope‐ratio detection for gas chromatography

Sessions¹

2006

J of Separation Science

244

270

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Isotope-ratio detection for gas chromatographyInstrumentation and methods exist for highly precise analyses of the stable-isotopic composition of organic compounds separated by GC. The general approach combines a conventional GC, a chemical reaction interface, and a specialized isotoperatio mass spectrometer (IRMS). Most existing GC hardware and methods are amenable to isotope-ratio detection. The interface continuously and quantitatively converts all organic matter, including column bleed, to a common molecular form for isotopic measurement. C and N are analyzed as CO 2 and N 2 , respectively, derived from combustion of analytes. H and O are analyzed as H 2 and CO produced by pyrolysis/reduction. IRMS instruments are optimized to provide intense, highly stable ion beams, with extremely high precision realized via a system of differential measurements in which ion currents for all major isotopologs are simultaneously monitored. Calibration to an internationally recognized scale is achieved through comparison of closely spaced sample and standard peaks. Such systems are capable of measuring 13 C/ 12 C ratios with a precision approaching 0.1? (for values reported in the standard delta notation), four orders of magnitude better than that typically achieved by conventional "organic" mass spectrometers. Detection limits to achieve this level of precision are typically a1 nmol C (roughly 10 ng of a typical hydrocarbon) injected on-column. Achievable precision and detection limits are correspondingly higher for N, O, and H, in that order.

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Section: Peak Resolutionmentioning

confidence: 93%

Section: Injection Methodsmentioning

confidence: 99%

Isotope‐ratio detection for gas chromatography

Sessions¹

2006

J of Separation Science

244

270

View full text Add to dashboard Cite

show abstract

“…Isotope fractionation was attributed to mass-dependent energy shifts during partitioning of the organic compound between the aqueous phase and the SPME fiber coating. Harris et al (15) used a hSPME method for carbon isotope analysis of gasoline range hydrocarbons in oils. They found a nonsystematic 13 C depletion or enrichment in the extracted compounds compared to results from a purge-and-trap method.…”

Section: Introductionmentioning

confidence: 99%

Determination of Compound-Specific Carbon Isotope Ratios of Chlorinated Methanes, Ethanes, and Ethenes in Aqueous Samples

Hunkeler

Aravena

2000

Environ. Sci. Technol.

115

129

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Compound-specific carbon isotope ratio analysis is a promising tool to assess the origin and fate of organic contaminants in groundwater. The aim of this study was to develop and evaluate a reliable, fast method to determine carbon isotope ratios of chlorinated methanes, ethanes, and ethenes in aqueous samples. Direct solid-phase microextraction (dSPME) and headspace solid-phase microextraction (hSPME) were selected as extraction method and compared to headspace equilibration. For dSPME and hSPME, deviations between carbon isotope ratios in the aqueous phase and on the SPME fiber were e 0.40‰. For headspace equilibration, molecules in the gas phase were enriched in 13 C compared to molecules in the aqueous phase by up to 1.46‰, in particular for chlorinated methanes. The absence of significant carbon isotope fractionation during dSPME and hSPME could be explained by the fact that both the aqueous phase and the SPME fiber coating discriminate against molecules with 13 C to a similar degree, and thus no net carbon isotope fractionation occurs. If aqueous phase/gas-phase carbon isotope fractionation during headspace equilibration is taken into account, all methods, dSPME, hSPME, and headspace equilibration, provide accurate δ 13 C values with a similar precision. Direct SPME was the most sensitive method with detection limits as low as 130 ppb.

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“…Strict collection and preservation procedures are required to avoid the evaporation of a crude oil sample to facilitate the accurate determination of its LMWHs distribution, because even minor evaporation would affect the quality of the data (Cañipa-Morales et al 2003). Although compound-specific isotope analysis (CSIA) has become a powerful tool for oil characterization and correlation (Chung et al 1998;Odden et al 1998;Harris et al 1999;Whiticar and Snowdon 1999), few studies have considered the effect of evaporation on the d 13 C values of LMWHs (Harrington et al 1999;Shin and Lee 2010).…”

Section: Introductionmentioning

confidence: 99%

Carbon isotopic fractionation during vaporization of low molecular weight hydrocarbons (C6–C12)

et al. 2017

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Three series of laboratory vaporization experiments were conducted to investigate the carbon isotope fractionation of low molecular weight hydrocarbons (LMWHs) during their progressive vaporization. In addition to the analysis of a synthetic oil mixture, individual compounds were also studied either as pure single phases or mixed with soil. This allowed influences of mixing effects and diffusion though soil on the fractionation to be elucidated. The LMWHs volatilized in two broad behavior patterns that depended on their molecular weight and boiling point. Vaporization significantly enriched the 13 C present in the remaining components of the C 6 -C 9 fraction, indicating that the vaporization is mainly kinetically controlled; the observed variations could be described with a Rayleigh fractionation model. In contrast, the heavier compounds (n-C 10 -n-C 12 ) showed less mass loss and almost no significant isotopic fractionation during vaporization, indicating that the isotope characteristics remained sufficiently constant for these hydrocarbons to be used to identify the source of an oil sample, e.g., the specific oil field or the origin of a spill. Furthermore, comparative studies suggested that matrix effects should be considered when the carbon isotope ratios of hydrocarbons are applied in the field.

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Molecular and isotopic analysis of oils by solid phase microextraction of gasoline range hydrocarbons

Cited by 41 publications

References 19 publications

Isotope‐ratio detection for gas chromatography

Isotope‐ratio detection for gas chromatography

Determination of Compound-Specific Carbon Isotope Ratios of Chlorinated Methanes, Ethanes, and Ethenes in Aqueous Samples

Carbon isotopic fractionation during vaporization of low molecular weight hydrocarbons (C6–C12)

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