Rapid Determination of Amino Acids in Fruits of Ziziphus jujuba by Hydrophilic Interaction Ultra-High-Performance Liquid Chromatography Coupled with Triple-Quadrupole Mass Spectrometry

In this study, a sensitive and rapid method for the simultaneous determination of free amino acids without derivatization using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry (HILIC–MS/MS) was developed. The method was performed on an ultra-high-performance liquid chromatography (UHPLC) separation system coupled with a triple-quadrupole mass spectrometry (TQ-MS) instrument. Sufficient separation of 23 underivatized amino acids was achieved on an Acquity BEH Amide column (2.1 mm × 100 mm, 1.7 μm) in a single run of 12 min. Then the method was applied for the analysis of the free amino acids in 46 batches of Ziziphus jujuba fruits which comprised 39 cultivars from 26 cultivation regions. Multivariate statistical analysis was also used to investigate the differences in free amino acid profiles among the samples. This study showed that HILIC–UHPLC–TQ-MS is an effective technique to analyze underivatized amino acids in the food samples.