Novel tool for d13C and d15N determination in aqueous samples

The quantitative and isotopic analysis of dissolved matter (e.g., dissolved carbon and nitrogen) is of particular importance in this pool as a prime conduit in the cycling of C and N. Studying these both abundance and isotopic value of these two elemental pools simultaneously offers insight into these linked biogeochemical cycles.

Dissolved carbon concentration and isotopic composition are routinely determined through coupling of high temperature combustion (HTC) systems to isotope ratio mass spectrometry (IRMS). However, the abundance and isotopic analysis of total dissolved nitrogen (TDN) has limitations. For instance, low concentrations of dissolved nitrogen in some settings makes preconcentration steps (i.e., lyophilization) followed by elemental analysis (EA) coupled to an IRMS a laborious approach and is subject to contamination or loss of material. Second, wet-chemical oxidation-IRMS runs the risk of incomplete chemical conversion and thus isotopic fractionation of the nitrogen pool. Lastly, this approach cannot distinguish between dissolved N2 and TDN. However, HTC-IRMS may provide a solution to simultaneously analyze dissolved carbon and nitrogen.