Liquid Chromatography−Mass Spectrometry Analysis. Quinoa seed sample from previously described extraction and acid hydrolysis was injected into a Dionex UHPLC UltiMate 3000 liquid chromatograph interfaced to an amaZon SL ion trap mass spectrometer (Bruker Daltonics, Billerica, MA). A C18 column (Agilent Poroshell 120 2.7 μm particle size, 150 mm × 4.6 mm) was used for chromatographic separation. The initial mobile phase conditions were 0.1% formic acid in water (v/v; mobile phase A) and 0.1% formic acid in acetonitrile (v/v; mobile phase B). The gradient went to 98% solvent B, with the flow rate maintained at 0.4 mL/min, in 30 min. The mass spectrometer electrospray capillary voltage was maintained at 4.5 kV and the drying temperature at 220 °C with a flow rate of 10 L/min. The nebulizer pressure was 40 psi. Nitrogen was used as both nebulizing and drying gas and helium was used as collision gas at 60 psi. The mass-to-charge ratio was scanned across the range m/z 50−1200 in enhanced resolution positive ion auto MS/MS mode. The smart parameter setting (SPS) was used to automatically optimize the trap drive level for precursor ions. The instrument was externally calibrated with the ESI TuneMix (Agilent). UV monitoring was at 280 nm for HMF derivatives.