15 October 2020 – New method for determining the isotopic composition of dissolved organic carbon

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15 October 2020 – New method for determining the isotopic composition of dissolved organic carbon

15 October 2020 – New automated method for determining the isotopic composition of dissolved organic carbon

Dissolved organic carbon (DOC) in water is a very important element of the carbon cycle used as a sensitive indicator of the processes of organic matter decomposition or a tracer of the quality of terrestrial and aquatic ecosystems. The analysis of 13C-COD at natural or enriched abundance levels informs precisely on its origin and dynamics.

After metrological tests, the Laboratory for Analysis of Stable Isotopes (LADIS) of the UMR FARE opens its new service of 13C-COD continuous flow analysis.

The analytical module (ISOTOC) includes an automatic sampler that makes it possible the injection of a flexible volume of solution (0.05 to 3 mL). Non-purgeable organic carbon compounds are quantitatively oxidized to CO2 by catalytic combustion under oxygen at 850°C. After passing over a separation interface, the CO2 is quantified using a NDIR detector (non-dispersive infrared detector) and then directed towards the isotope ratio mass spectrometer (IRMS, ISOPRIME PRECISION) for the determination of δ 13C.

Following an "off line" removal step of the mineral carbon from the sample, the device allows rapid routine analysis (analysis time of 10 minutes), with an excellent precision and very good reproducibility (coefficient of variation for the carbon concentration and the delta 13C respectively lower than 1% and 0.4%).

Contact:

Olivier Delfosse (olivier.delfosse@inrae.fr), Gonzague Alavoine (gonzague.alavoine@inrae.fr)

See also

Visit our Isotopic Analysis tab, /Isotope-Analysis, for more details on the analytical capabilities of the Laboratory.

Modification date : 06 June 2023 | Publication date : 15 October 2020 | Redactor : G. Lashermes