Simultaneous on-line analysis of 18 O/ 16 O and 13 C/ 12 C ratios of organic compounds using GC-pyrolysis-IRMS

Hener, Uwe; Brand, Willi A.; Hilkert, Andreas; Juchelka, Dieter; Mosandl, Armin; Podebrad, Frank

doi:10.1007/s002170050249

Cited by 60 publications

(40 citation statements)

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“…18,19 The first officially adopted stable isotope method in the European Community was the site-specific D/H ratio determination by site-specific natural isotope fractionation (SNIF) NMR 1 20 in wine ethanol, mainly for proof of beet-sugar addition. The D/H ratios in the methyl and methylene groups of ethanol are closely related to the D/H ratios of the starting sugar and the fermentation water.…”

Section: Resultsmentioning

confidence: 99%

“…The tube is left empty, no carbon is added and there is no Pt or other catalyst in the hot zone. This is markedly different from other approaches and in particular from the high temperature conversion system for measuring 18 O/ 16 O ratios 6,8 where contact between the CO product gas and oxygen bearing walls within the hot zone must be avoided.…”

Section: Methodsmentioning

confidence: 97%

“…5 The measurement of 18 O proved to be particularly difficult and was made available only recently. [6][7][8] The essential characteristics of irm-GC/MS that differentiate it from other techniques, such as GC/MS, are -sample peaks are converted post GC from the original chemical form to the characteristic analyte (for C, it is CO 2 ; for N, it is N 2 ; for O, it is CO). Whenever achievable, the analyte is purified on-line from other reaction products such that it is the only chemical species in the carrier stream; -dedicated magnetic sector field mass spectrometers which have a high sensitivity (around 1 ion detected per 1000 molecules) and which collect the respective ion currents simultaneously in an array of Faraday cups positioned along the ion optical focal plane and -connection between the GC/combustion device and the IRMS must be made with an open split in order to avoid isotopic fractionation.…”

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confidence: 99%

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Isotope ratio monitoring gas chromatography/Mass spectrometry of D/H by high temperature conversion isotope ratio mass spectrometry

Hilkert¹,

Douthitt²,

Schlüter³

et al. 1999

Rapid Commun. Mass Spectrom.

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290

211

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Of all the elements, hydrogen has the largest naturally occurring variations in the ratio of its stable isotopes (D/H). It is for this reason that there has been a strong desire to add hydrogen to the list of elements amenable to isotope ratio monitoring gas chromatography/mass spectrometry (irm-GC/MS). In irm-GC/MS the sample is entrained in helium as the carrier gas, which is also ionized and separated in the isotope ratio mass spectrometer (IRMS). Because of the low abundance of deuterium in nature, precise and accurate on-line monitoring of D/H ratios with an IRMS requires that low energy helium ions be kept out of the m/z 3 collector, which requires the use of an energy filter. A clean mass 3 (HD(+.)) signal which is independent of a large helium load in the electron impact ion source is essential in order to reach the sensitivity required for D/H analysis of capillary GC peaks. A new IRMS system, the DELTA(plus)XL(trade mark), has been designed for high precision, high accuracy measurements of transient signals of hydrogen gas. It incorporates a retardation lens integrated into the m/z 3 Faraday cup collector. Following GC separation, the hydrogen bound in organic compounds must be quantitatively converted into H(2) gas prior to analysis in the IRMS. Quantitative conversion is achieved by high temperature conversion (TC) at temperatures >1400 degrees C. Measurements of D/H ratios of individual organic compounds in complicated natural mixtures can now be made to a precision of 2 per thousand (delta notation) or, better, with typical sample amounts of approximately 200 ng per compound. Initial applications have focused on compounds of interest to petroleum research (biomarkers and natural gas components), food and flavor control (vanillin and ethanol), and metabolic studies (fatty acids and steroids). Copyright 1999 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 97%

mentioning

confidence: 99%

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Isotope ratio monitoring gas chromatography/Mass spectrometry of D/H by high temperature conversion isotope ratio mass spectrometry

Hilkert¹,

Douthitt²,

Schlüter³

et al. 1999

Rapid Commun. Mass Spectrom.

Self Cite

290

211

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show abstract

“…Still, published reports are appearing only slowly and focus primarily on its application for biochemical tracing [68] and natural products authentication [69][70][71][72] All GC-IRMS analyses of organic O rely on pyrolysis and reduction of organic molecules over carbon to quantitatively yield CO as the analyzed species. An additional concern for CO (relative to H 2 ) is the possibility of isotopic exchange between CO and Al 2 O 3 in the high-temperature pyrolysis reactor.…”

Section: Oxygen Isotopesmentioning

confidence: 99%

“…An additional concern for CO (relative to H 2 ) is the possibility of isotopic exchange between CO and Al 2 O 3 in the high-temperature pyrolysis reactor. For this reason, most systems utilize pyrolysis reactors constructed of alumina (typically 0.8 mm id) and lined with Pt or Ni tubes [68,70,71]. Pyrolysis/reduction reactors must be conditioned as for HD analyses by the periodic injection of organic compounds [70], and are typically operated at temperatures of 1200-13008C.…”

Section: Oxygen Isotopesmentioning

confidence: 99%

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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A laser extraction/combustion technique for in situ δ13C analysis of organic and inorganic materials

Wieser¹,

Brand²

1999

Rapid Commun. Mass Spectrom.

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A CO(2) laser extraction system is described for in situ delta(13)C analysis of organic and inorganic materials. Carbonaceous compounds volatilized by the laser are quantitatively converted to CO(2) gas by a combustion furnace mounted after the sample chamber. Gases produced by the laser and combustion processes are swept by helium carrier gas and separated by a packed gas chromatography column prior to their introduction to an isotope ratio monitoring mass spectrometer. A sample of lentil bean was analyzed at a spatial resolution of 200 µm and yielded delta(13)C values with precision of +/- 0.3 per thousand. The accuracy of delta(13)C measurements was better than +/- 0.5 per thousand from NBS 22 (mineral oil), USGS 24 (graphite), and IAEA CO-1 (calcium carbonate). Copyright 1999 John Wiley & Sons, Ltd.

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Simultaneous on-line analysis of 18 O/ 16 O and 13 C/ 12 C ratios of organic compounds using GC-pyrolysis-IRMS

Cited by 60 publications

References 0 publications

Isotope ratio monitoring gas chromatography/Mass spectrometry of D/H by high temperature conversion isotope ratio mass spectrometry

Isotope ratio monitoring gas chromatography/Mass spectrometry of D/H by high temperature conversion isotope ratio mass spectrometry

Isotope‐ratio detection for gas chromatography

A laser extraction/combustion technique for in situ δ13C analysis of organic and inorganic materials

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