Stable carbon isotope analysis of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in natural waters – Results from a worldwide proficiency test

Geldern, Robert van; Verma, Mahendra P.; Carvalho, Matheus Carvalho de; Grassa, Fausto; Huertas, António Delgado; Monvoisin, Gaël; Barth, Johannes A. C.

doi:10.1002/rcm.6665

Cited by 31 publications

(35 citation statements)

References 23 publications

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“…Our δ 13 C‐DIC intercomparison study involving 16 groups worldwide showed between‐lab reproducibility of uncorrected raw values (±0.11‰) comparable to that reported from the only previous published interlaboratory comparison of seawater analyses (van Geldern et al ), which was limited to only five groups. The level of between‐lab reproducibility was also not statistically different from the magnitude and variability of offsets between historical cruise data sets detected by crossover analysis.…”

Section: Conclusion and Recommendationssupporting

confidence: 87%

“…In this study, the between‐lab reproducibility ( δ 13 C stdev ) for both RM and DSW, before correction based on RMs but after outlier removal, was 0.11‰. The only previously published assessment by van Geldern et al () involved only five groups and reported between‐lab reproducibility ( δ 13 C stdev ) as low as 0.07‰ for results from four laboratories but reaching 0.47‰ when results from all five laboratories were included.…”

Section: Discussionmentioning

confidence: 44%

“…Intercomparisons of this type have been conducted for oxygen and hydrogen stable isotope compositions of water ( δ 2 H‐H 2 O and δ 18 O‐H 2 O; e.g., Walker et al ; Wassenaar et al ; Verma et al ), seawater nutrient concentrations (Aoyama et al ), and seawater DIC and alkalinity concentrations (Bockmon and Dickson ; Verma et al ). However, to the authors’ knowledge, there has been only one published interlaboratory comparison study of δ 13 C‐DIC measurements on natural waters (van Geldern et al ). In their study, five groups measured a wide variety of natural water samples, including replicate samples of seawater.…”

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confidence: 99%

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An international intercomparison of stable carbon isotope composition measurements of dissolved inorganic carbon in seawater

Cheng

Normandeau

Bowden

et al. 2019

Limnology & Ocean Methods

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We report results of an intercomparison of stable carbon isotope ratio measurements in seawater dissolved inorganic carbon (δ13C‐DIC) which involved 16 participating laboratories from various parts of the world. The intercomparison involved distribution of samples of a Certified Reference Material for seawater DIC concentration and alkalinity and a preserved sample of deep seawater collected at 4000 m in the northeastern Atlantic Ocean. The between‐lab standard deviation of reported uncorrected values measured with diverse analytical, detection, and calibration methods was 0.11‰ (1σ). The multi‐lab average δ13C‐DIC value reported for the deep seawater sample was consistent within 0.1‰ with historical measured values for the same water mass. Application of a correction procedure based on a consensus value for the distributed reference material, improved the between‐lab standard deviation to 0.06‰. The magnitude of the corrections were similar to those used to correct independent data sets using crossover comparisons, where deep water analyses from different cruises are compared at nearby locations. Our results demonstrate that the accuracy/uncertainty target proposed by the Global Ocean Observing System (±0.05‰) is attainable, but only if an aqueous phase reference material for δ13C‐DIC is made available and used by the measurement community. Our results imply that existing Certified Reference Materials used for seawater DIC and alkalinity quality control are suitable for this purpose, if a “Certified” or internally consistent “consensus” value for δ13C‐DIC can be assigned to various batches.

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Section: Conclusion and Recommendationssupporting

confidence: 87%

Section: Discussionmentioning

confidence: 44%

mentioning

confidence: 99%

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An international intercomparison of stable carbon isotope composition measurements of dissolved inorganic carbon in seawater

Cheng

Normandeau

Bowden

et al. 2019

Limnology & Ocean Methods

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“…Over the last decade, WCO analysis has become a routine analytical technique . However, a unified world‐wide laboratory protocol for selecting soluble international isotope reference materials has not yet been established, creating the potential for inconsistency in results obtained by different laboratories.…”

Section: Introductionmentioning

confidence: 99%

Reference materials selection for the stable carbon isotope analysis of dissolved carbon using a wet oxidation system

Skrzypek

Ford

2019

Rapid Comm Mass Spectrometry

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Rationale Wet chemical oxidation combined with isotope ratio mass spectrometry has become a routine technique for analyzing the stable carbon isotope composition of dissolved organic (DOC) and inorganic (DIC) carbon. However, methodological inconsistencies between laboratories in using different reference materials lead to a discrepancy in results. We experimentally tested the precision and accuracy of the analysis of commonly available international reference materials and other chemicals potentially suitable for laboratory standards. Methods The solid international reference materials and other simple chemicals were used to prepare water solutions. A range of carbon concentrations was chosen to optimize tests for (1) precision and accuracy, (2) linearity, (3) detection limits, (4) memory effects, and (5) efficiency of DIC removal from a DOC/DIC mixtures. Samples were analyzed using an LC‐IsoLink coupled with a Delta V Plus isotope ratio mass spectrometer (Thermo Fisher Scientific). Results The analytical setup had a negligible memory effect, good reproducibility (<0.21‰) and accuracy (maximum difference from the true values <0.35‰) for the analyzed organic compounds if approximately ≥9 × 10−09 moles of dissolved carbon was injected into the system (~11 mg C L−1 if a 10‐μL loop was used). Analyses of sodium bicarbonate or calcium carbonate solutions had a two‐fold lower accuracy despite maintaining a high precision. Conclusions Aqueous solutions of international reference materials such as L‐glutamic acids (USGS40, USGS41), benzoic acid (IAEA‐601) and sucrose (IAEA‐CH‐6) can be successfully used for direct normalization of results to the VPDB scale. By contrast, analyses of caffeine and urea returned very reproducible but highly inaccurate results and these materials are not recommended for standards.

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“…In addition, the large quantities of chlorine gas produced as a byproduct of WO in seawater, causes the rapid corrosion of some parts of the reaction vessel, the fouling of the halide/sulfide traps, and the rapid exhaustion of reducing agents. As part of a recent intercomparison study, two different labs using wet chemical oxidation measured the δ 13 C-DOC of a single seawater sample to be -9.3 and -11.0‰ (Van Geldern et al 2013), an 8 to 10‰ δ 13 C enrichment over values generally reported for seawater DOC (-20.1 to -22.9‰;Bauer 2002 and references therein), probably caused by a WO method artifact.…”

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confidence: 99%

Untitled

2014

Limnology & Ocean Methods

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We provide a detailed description of the hyphenation of an Aurora 1030C high temperature catalytic conversion DOC analyzer, a GD-100 CO 2 trap and a continuous flow IRMS, which has made possible the highthroughput, automated measurements of ), comparable to that obtained in a conventional elemental analyzer-IRMS setup. The system blank contribution is the limiting factor in obtaining maximal performance; optimal system blanks values are on the order of 0.2 μg C with an isotopic signature varying from -20 to -12‰ during the lifetime of the combustion column. With appropriate blank correction procedures, accurate analyses (±0.5‰ or better) can be obtained on concentrations as low as 0.5 mg DOC L -1 , representing the lower limit typically observed in aquatic systems. Sample matrix does not affect reproducibility or accuracy; this method is amenable to both freshwater and seawater samples. Although no certified DOC standards exist for δ 13 C, our two laboratories analyzed a consensus reference material from a deep-ocean environment (CRM Batch 13 Lot # 05-13, Hansell 2013) and found δ 13 C values of -19.9 ± 0.5‰ (n = 4) and -20.6 ± 0.3‰ (n = 3), which corroborates previously reported values for similar samples (Bouillon et al. 2006;Lang et al. 2007;Panetta et al. 2008) and is consistent with its marine origin.

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Stable carbon isotope analysis of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in natural waters – Results from a worldwide proficiency test

Cited by 31 publications

References 23 publications

An international intercomparison of stable carbon isotope composition measurements of dissolved inorganic carbon in seawater

An international intercomparison of stable carbon isotope composition measurements of dissolved inorganic carbon in seawater

Reference materials selection for the stable carbon isotope analysis of dissolved carbon using a wet oxidation system

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