A novel high‐temperature combustion based system for stable isotope analysis of dissolved organic carbon in aqueous samples. II: optimization and assessment of analytical performance. (20th October 2014)

• Record Type: Journal Article
• Authors: Kirkels, F. M. S. A.; Cerli, C.; Federherr, E.; Gao, J.; Kalbitz, K.
• Is Part Of: Rapid communications in mass spectrometry. Volume 28:Number 23(2014)
• Page Start: 2574
• Page End: 2586
• Publication Date: 2014-10-20
• Subjects: Mass spectrometry -- Periodicals; 543.65
• DOI: 10.1002/rcm.7053
• Languages: English
• ISSNs: 0951-4198

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="rcm7053-sec-0001" sec-type="section"> <title>RATIONALE</title> <p>Dissolved organic carbon (DOC) plays an important role in carbon cycling, making precise and routine measurement of <italic>δ</italic><sup>13</sup>C values and DOC concentration highly desirable. A new promising system has been developed for this purpose. However, broad‐scale application of this new technique requires an in‐depth assessment of analytical performance, and this is described here.</p> </sec> <sec id="rcm7053-sec-0002" sec-type="section"> <title>METHODS</title> <p>A high‐temperature combustion Total Organic Carbon analyzer was interfaced with continuous flow isotope ratio mass spectrometry (TOC/IRMS) for the simultaneous analysis of the bulk DOC concentration and <italic>δ</italic><sup>13</sup>C signature. The analytical performance (precision, memory effects, linearity, volume/concentration effects, accuracy) was thoroughly evaluated, including realistic and challenging conditions such as low DOC concentrations and natural DOC.</p> </sec> <sec id="rcm7053-sec-0003" sec-type="section"> <title>RESULTS</title> <p>High precision (standard deviation, SD predominantly ≤0.15 ‰) and accuracy (R<sup>2</sup> = 0.9997) were achieved for the <italic>δ</italic><sup>13</sup>C analysis of a broad diversity of DOC solutions. Simultaneously, good results were obtained for the measurement of DOC concentration. Assessment of natural abundance and slightly <sup>13</sup>C‐enriched DOC, a wide range of concentrations (~0.2–150 mgC/L) and injection volumes (0.05–3 mL), demonstrated minor/negligible memory effects, good linearity and flexible usage. Finally, TOC/IRMS was successfully applied to determine low DOC concentrations (<2 mgC/L) and DOC from diverse terrestrial, freshwater and marine environments (SD ≤0.23 ‰).</p> </sec> <sec id="rcm7053-sec-0004" sec-type="section"> <title>CONCLUSIONS</title> <p>TOC/IRMS enables fast and reliable measurement of DOC concentrations and <italic>δ</italic><sup>13</sup>C values in aqueous samples, without pre‐concentration and freeze‐drying. Further investigations should focus on complex, saline matrices and very low DOC concentrations, to achieve a potential lower limit of 0.2 mgC/L. Thus, TOC/IRMS will give DOC research in terrestrial and aquatic environments a huge impulse with high‐resolution, routine <italic>δ</italic><sup>13</sup>C analysis. Copyright © 2014 John Wiley & Sons, Ltd.</p> </sec> </abstract>