This study led by Richard Gruseck and Michael Zumstein, with contributions from Thilo Hofmann, Marton Palatinsky, and Michael Wagner, focused on the further development and adaptation of an existing method to quantify guanidine. The resulting method, which is based on derivatization and LC-MS analysis, enables guanidine detection at concentrations in the range of 10 nanomolar and is applicable to human urine, wastewater, different biological growth media, and samples from other environments. This publication complements the recent Nature article on the "Growth of complete ammonia oxidizers on guanidine".
