Improvements in Mass Spectrometers for the Measurement of Small Differences in Isotope Abundance Ratios

McKinney, C. R.; McCrea, J. M.; Epstein, Samuel; Allen, Harriet A.; Urey, Harold C.

doi:10.1063/1.1745698

Cited by 610 publications

(222 citation statements)

References 3 publications

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“…Second, highly specialized mass spectrometers that maximize ion beam current and stability at the expense of mass resolution and dynamic range are employed (described in Section 5). Third, a system of differential measurements is employed in which sample and standard are repeatedly compared [2].…”

Section: Principles Of Stable Isotope Analysismentioning

confidence: 99%

“…2). This arrangement, though seemingly archaic in its similarity to the earliest mass spectrometers [2], remains the best choice for maximizing ionization efficiency and transmission, providing large (lA) and stable ion beams, and affording highly stable detection of ion-beam currents.…”

Section: Isotope-ratio Msmentioning

confidence: 99%

“…The use of multiple detectors to monitor two or three masses simultaneously effectively cancels fluctuations in ion beam intensity [2] and obviates the need for peak jumping. While the design of the Faraday detectors themselves has changed little over the past 50 years, reducing noise and stray capacitance in the electrometers remain an area of active development, particularly for D/H analyses.…”

Section: Isotope-ratio Msmentioning

confidence: 99%

“…Although invented more than 65 years ago [1,2], the isotope-ratio mass spectrometer (IRMS) was not successfully adapted as a detector for GC until the late 1970s [3,4]. Even today, high-precision isotope-ratio detection of GC analytes remains a somewhat specialized endeavor, and is practiced by no more than a few hundred laboratories worldwide.…”

Section: Introductionmentioning

confidence: 99%

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Isotope‐ratio detection for gas chromatography

Sessions¹

2006

J of Separation Science

236

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: Principles Of Stable Isotope Analysismentioning

confidence: 99%

Section: Isotope-ratio Msmentioning

confidence: 99%

Section: Isotope-ratio Msmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Isotope‐ratio detection for gas chromatography

Sessions¹

2006

J of Separation Science

236

270

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“…This method can be used with very small samples, and has precision suitable for quantifying most variations caused by radioactive decay and other nuclear processes (e.g., of the order of 1-10 parts per thousand uncertainty in the ratio). Relatively few Ar isotope ratio measurements have been made by dynamic dual-inlet mass spectrometry [23,24], which can require larger amounts of gas, but can be done with superior precision (e.g., of the order of 0.01 parts per thousand uncertainty in the ratio in some cases). This method has been used in studies of small isotopic variations; for example, those related to mass-dependent isotopic fractionation caused by diffusion, dissolution, and other processes not involving nuclear transformations.…”

Section: Reference Materials and Reporting Of Isotope Ratiosmentioning

confidence: 99%

Variation in the terrestrial isotopic composition and atomic weight of argon (IUPAC Technical Report)

Böhlke

2014

Pure and Applied Chemistry

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Abstract:The isotopic composition and atomic weight of argon (Ar) are variable in terrestrial materials. Those variations are a source of uncertainty in the assignment of standard properties for Ar, but they provide useful information in many areas of science. Variations in the stable isotopic composition and atomic weight of Ar are caused by several different processes, including (1) isotope production from other elements by radioactive decay (radiogenic isotopes) or other nuclear transformations (e.g., nucleogenic isotopes), and (2) Ar) at various levels of precision are widely used for studies in geochronology, water-rock interaction, atmospheric evolution, and other fields.

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Routine analysis by high precision gas chromatography/mass selective detector/isotope ratio mass spectrometry to 0.1 parts per mil

Hall¹,

Barth²,

Kalin³

1999

Rapid Commun. Mass Spectrom.

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Stable isotope methods are potentially quite useful for validating natural or enhanced mineral degradation of contaminants. For this reason, a continuous flow gas chromatograph (GC), isotope ratio mass spectrometer (IRMS) has been coupled with a quadrupole mass selective detector (MSD) to allow simultaneous mass spectral and stable carbon isotope ratio data to be obtained from a single chromatographic analysis. This allows the target contaminant and any extra-cellular degradation intermediates to be both qualified and quantified. Previously acceptable limits of precision (0.3 parts per mil) are undesirable given the small fractionation observed during aerobic degradation. To further understand the fate of organic contaminants and to gain information about the metabolic degradative pathway employed by a microorganism, routine isotopic analyses on a range of analytes have been performed. Quantities of sample producing mass-44 ion beam signal (I(44)) of 2 x 10(-10) to 1 x 10(-8) A were analysed. When the IRMS was tuned for high sensitivity, ion source nonlinearities were overcome by peak height correction from an algorithm that was produced using known isotopic standards of varying concentrations. This led to sample accuracy of <0.01 per thousand and sample precision of 0.1 per thousand. Copyright 1999 John Wiley & Sons, Ltd.

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Improvements in Mass Spectrometers for the Measurement of Small Differences in Isotope Abundance Ratios

Cited by 610 publications

References 3 publications

Isotope‐ratio detection for gas chromatography

Isotope‐ratio detection for gas chromatography

Variation in the terrestrial isotopic composition and atomic weight of argon (IUPAC Technical Report)

Routine analysis by high precision gas chromatography/mass selective detector/isotope ratio mass spectrometry to 0.1 parts per mil

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