The purity of reuterin in samples was assessed by high resolution electrospray ionization mass spectrometry (HRESIMS) performed on a Bruker maXis QTOF spectrometer, and Nuclear Magnetic Resonance (NMR) spectroscopy acquired on a Bruker AVANCE III 500-MHz NMR spectrometer equipped a with a 1.7 mm TCI cryoprobe. The mass spectrometer was operated in positive ESI mode. The instrumental parameters were: 4 kV capillarity voltage, drying gas flow of 1 L/min at 200 C, nebulizer pressure at 2.8 bars. TFA-Na cluster ions were used for mass calibration of the instrument
prior to samples injection. Pre-run calibrationwas by infusion with the same TFA-Na calibrant. NMR spectra (500 and 125 MHz for 1H and 13C NMR, respectively) were recorded in CD3OD, using the signals of the residual solvent as internal references (dH 3.31 and dC 49.0 ppm). The purified reuterin without contaminants was diluted in sterile distilled water to about 100 mg/ml solution and stored at 40 C until use.