Challenges in measuring nitrogen isotope signatures in inorganic nitrogen forms: An interlaboratory comparison of three common measurement approaches.

Rationale: Stable isotope approaches are increasingly applied to better understand the cycling of inorganic nitrogen (N ) forms, key limiting nutrients in terrestrial and aquatic ecosystems. A systematic comparison of the accuracy and precision of the most commonly used methods to analyze δ N in NO and NH and interlaboratory comparison tests to evaluate the comparability of isotope results between laboratories are, however, still lacking.

Methods: Here, we conducted an interlaboratory comparison involving 10 European laboratories to compare different methods and laboratory performance to measure δ N in NO and NH .