2. Experimental
2.1. Chemicals and solvents
With the exception of semicarbazide (SC), the metabolites under investigation are not commercially available. Several milligrams of AOZ and AMOZ were provided by the Bundesanstalt für Tierseuchenbekämpfung (Federal Research Centre for Animal Diseases, Mödling, Austria) while 1-aminohydantoin (AH) was synthesised according to the three-step synthesis of Jack [18]. Semicarbazide hydrochloride (p.a. grade) was bought from Fluka (Buchs, Switzerland). Stock solutions were prepared in methanol, wrapped in aluminum foil and stored at 4°C for a maximum of 2 months.