Stücheli, Patrick E., Jutta Niggemann, and Carsten J. Schubert. 2018. “Comparison of Different Solid Phase Extraction Sorbents for the Qualitative Assessment of Dissolved Organic Nitrogen in Freshwater Samples Using FT-ICR-MS: SPE Sorbent Comparison for DON Extraction”. Journal of Limnology 77 (3). https://doi.org/10.4081/jlimnol.2018.1791.