Isotope-Ratio and Background Corrections for Accelerator Mass Spectrometry Radiocarbon Measurements

Donahue, D. J.; Linick, T. W.; Jull, A. J. T.

doi:10.1017/s0033822200040121

Cited by 365 publications

(281 citation statements)

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“…where (14C/13C) is the sample ratio, normalized to S13C = -25%o, and is the calculated standard ratio at 1950, determined from measurements of NBS oxalic acid standards, also normalized to &3C = -25%o (Donahue, Linick & Jull 1990 where M is the uncertainty in the system background. Details of the calculation, including a discussion of background, are given in Donahue, Linick and Jull (1990) and Donahue, Jull, and Toolin (1990).…”

Section: Ams Sample Preparation and Analysismentioning

confidence: 99%

Mass Spectrometric ¹⁴C and U-Th Measurements in Coral

et al. 1992

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ABSTRACT. We discuss U-Th and 14C measurements in coral. Samples with U-Th dates in excess of 50 ka BP were chosen for study. Some bulk samples from this group have measurable 14C dates, which range from 30 ka to 43 ka BP. These can be explained by 0.5-2.5% contamination by modern carbon. This small amount of contamination can produce significant offsets in 14C dates of coral samples older than -10 ka. It may be undetectable in X-ray powder diffraction patterns. We describe a sample pretreatment that removes the modern carbon by selective dissolution and produces accurate 14C dates.

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Section: Ams Sample Preparation and Analysismentioning

confidence: 99%

Mass Spectrometric ¹⁴C and U-Th Measurements in Coral

et al. 1992

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“…27 Thus the adjustment (0.975/0.9822) appears in the equation below. So, the biological isotopic fractionation in the biological sample is normalized to a constant atmospheric 13 C content by [0.975/(1 + δ 13 C sample /1000)].…”

Section: Methodsmentioning

confidence: 99%

Carbon Isotopes Profiles of Human Whole Blood, Plasma, Red Blood Cells, Urine and Feces for Biological/Biomedical ¹⁴C-Accelerator Mass Spectrometry Applications

et al. 2011

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Radiocarbon (14C) is an ideal tracer for in vivo human ADME (absorption, distribution, metabolism, elimination) and PBPK (physiological-based pharmacokinetic) studies. Living plants preferentially incorporate atmospheric 14CO2, vs 13CO2, vs 12CO2, which result in unique signature. Furthermore, plants and the food chains they support also have unique carbon isotope signatures. Humans, at the top of the food chain, consequently acquire isotopic concentrations in the tissues and body fluids depending on their dietary habits. In preparation of ADME and PBPK studies, 12 healthy subjects were recruited. The human baseline (specific to each individual and their diet) total carbon (TC) and carbon isotope 13C (δ13C) and 14C (Fm) were quantified in whole blood (WB), plasma, washed red blood cell (RBC), urine, and feces. TC (mg of C/100μL) in WB, plasma, RBC, urine, and feces were 11.0, 4.37, 7.57, 0.53, and 1.90, respectively. TC in WB, RBC, and feces was higher in men over women, P < 0.05. Mean δ13C were ranked low to high as follows, feces < WB = plasma = RBC = urine, P < 0.0001. δ13C was not affected by gender. Our analytic method shifted δ13C by only ± 1.0 ‰ ensuring our Fm measurements were accurate and precise. Mean Fm were ranked low to high as follows, plasma = urine < WB = RBC = feces, P < 0.05. Fm in feces was higher for men over women, P < 0.05. Only in WB, 14C levels (Fm) and TC were correlated with one another (r = 0.746, P < 0.01). Considering the lag time to incorporate atmospheric 14C into plant foods (vegetarian) and or then into animal foods (non-vegetarian), the measured Fm of WB in our population (recruited April 2009) was 1.0468 ± 0.0022 (mean±SD), the Fm of WB matched the (extrapolated) atmospheric Fm of 1.0477 in 2008. This study is important in presenting a procedure to determine a baseline for a study group for human ADME and PBPK studies using 14C as a tracer.

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“…where ( 14 C/ 13 C) S is the measured ratio in the sample, normalized to δ 13 C = -25‰, and ( 14 C/ 13 C) STD is the calculated modern standard ratio at AD 1950, determined from measurements of NBS oxalic acid standards, also normalized to -25‰ (Donahue et al 1990). The 14 C age of a sample is then calculated from F as:…”

Section: Reservoir Age Calculationsmentioning

confidence: 99%

Modern and Pleistocene Reservoir Ages Inferred from South Pacific Corals

et al. 2009

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ABSTRACT. This paper presents radiocarbon results from modern South Pacific corals from the Marquesas Islands, Vanuatu, Papua New Guinea (PNG), and Easter Island. All of the measurements are from pre-bomb Porites corals that lived during the 1940s and 1950s. The data reflect subannual to multiannual surface ocean 14 C variability and allow for precise, unambiguous reservoir age determinations. The results are compared with published values from other coral records throughout the South Pacific, with striking consistency. By comparisons with other published values, we identify 3 South Pacific regions with uniform pre-bomb reservoir ages (1945 to 1955). These are 1) the Central Equatorial South Pacific (361.6 ± 8.2 14 C yr, 2 σ); 2) the Western Equatorial South Pacific (322.1 ± 8.6 14 C yr, 2 σ); and 3) the subtropical Pacific (266.8 ± 13.8 14 C yr, 2 σ).The question of how much, and how fast, South Pacific reservoir ages might have varied in the past is addressed by examining a published record from a Pleistocene coral from Vanuatu that lived over a 700-yr period during the Younger Dryas. The average reservoir age at that time was larger than today, by ~150 yr, and exhibited reservoir age variability on a decadal timescale not seen in modern times. Measured paleo-reservoir ages increase sharply in this record by as many as 300 14 C yr in 3 decades. These increases are punctuated by smaller reservoir age decreases, on the order of 150 yr. This reservoir age variability provides a rare picture of active ocean ventilation and ocean-atmosphere exchange at the close of the Pleistocene.

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Isotope-Ratio and Background Corrections for Accelerator Mass Spectrometry Radiocarbon Measurements

Cited by 365 publications

References 3 publications

Mass Spectrometric ¹⁴C and U-Th Measurements in Coral

Mass Spectrometric ¹⁴C and U-Th Measurements in Coral

Carbon Isotopes Profiles of Human Whole Blood, Plasma, Red Blood Cells, Urine and Feces for Biological/Biomedical ¹⁴C-Accelerator Mass Spectrometry Applications

Modern and Pleistocene Reservoir Ages Inferred from South Pacific Corals

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Isotope-Ratio and Background Corrections for Accelerator Mass Spectrometry Radiocarbon Measurements

Cited by 365 publications

References 3 publications

Mass Spectrometric 14C and U-Th Measurements in Coral

Mass Spectrometric 14C and U-Th Measurements in Coral

Carbon Isotopes Profiles of Human Whole Blood, Plasma, Red Blood Cells, Urine and Feces for Biological/Biomedical 14C-Accelerator Mass Spectrometry Applications

Modern and Pleistocene Reservoir Ages Inferred from South Pacific Corals

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Mass Spectrometric ¹⁴C and U-Th Measurements in Coral

Mass Spectrometric ¹⁴C and U-Th Measurements in Coral

Carbon Isotopes Profiles of Human Whole Blood, Plasma, Red Blood Cells, Urine and Feces for Biological/Biomedical ¹⁴C-Accelerator Mass Spectrometry Applications