In Situ Quantification of Ammonia in Biofluids using High-Resolution Nuclear Magnetic Resonance.

Ammonia is an important metabolite and is involved in many physiological processes; the abnormal level of ammonia in vivo is correlated with the different phenotypes of diseases. Quantification of ammonia is important for disease diagnosis. However, in situ analysis of ammonia remains challenging due to the limitations of conventional methods, such as the toxicity of reactants and interference by amine analytes. Herein, we established a simple and reliable method for in situ quantification of ammonia using a series of ¹⁹F-Tags that are reactive to ammonia in aqueous solution and produce well-resolved NMR signals from other amine analytes in the NMR spectrum. This method has been effectively employed in the in situ quantification of ammonia at micromolar concentrations in biofluids, including cell lysates, human plasma, and human urine.