AbstractIn the determination of ammonia in sera usingo‐benzenesulfonamido‐p‐benzoquinone proteins cause false positive results. These findings contradict the reaction mechanism postulated in lit., according to which a dimer is formed through an NH‐bridge. As deduced by1H‐NMR‐, IR‐, UV‐, and mass spectroscopic investigations of the reaction product and by semi‐empirical MO‐calculations, charge transfer (CT)‐complexes3aare formed with ammonia as well as with proteins, amino acids, and amines. These CT‐complexes are in a solvent dependent equilibrium with their salts3b. Depending on the electron density of the amine compound, different subsequent