A novel method for dissolved organic carbon (DOC) isotopic (δ13C) and concentration analysis in environmental samples

Frederique Kirkels1, Chiara Cerli1, Eugen Federherr2, Karsten Kalbitz1
1 University of Amsterdam
2 University of Duisburg-Essen, Elementar Analysensysteme GmbH

P 7.12 in Controls of dissolved organic matter fluxes in ecosystems

Poster Session 1 on Monday, 16:30-18:30

Dissolved organic carbon (DOC) plays an important role in aquatic and terrestrial carbon cycling, making precise and routine analysis of δ13C and DOC concentration highly desirable. A new promising system was developed for this purpose, coupling a high-temperature combustion TOC analyzer trough an interface with a continuous flow isotope ratio mass spectrometer (Elementar group, Hanau, Germany) to enable simultaneous concentration and isotopic (bulk δ13C) analysis for complex mixtures as natural DOC. We present an assessment of its analytical performance inclusive environmental DOC samples, to support broad-scale application of this new technique. High precision (SD predominantly ≤ 0.15 ‰) and accuracy (R2 = 0.9997, i.e. comparison TOC-IRMS and conventional EA-IRMS) was achieved for isotopic analysis of diverse DOC solutions. Analysis of natural abundance and slightly 13C enriched DOC, a wide range of concentrations (0.2-150 mgC/L) and injection volumes (0.05-3 ml), demonstrated good analytical performance without memory, concentration/volume effects and a wide linearity. Finally, TOC-IRMS was successfully applied to analyze low DOC concentrations (< 2 mgC/L) and DOC from diverse terrestrial, freshwater and marine environments (SD ≤ 0.23 ‰). In conclusion, TOC-IRMS enables reliable fast and analysis of DOC concentration and δ13C in liquid samples, without pre-concentration/freeze-drying.

Letzte Änderung 31.03.2014