Direct determination of underivatized amino acids from Ginkgo biloba leaves by using hydrophilic interaction ultra high performance liquid chromatography coupled with triple quadrupole mass spectrometry

Ginkgo biloba leaf extract has been widely used in dietary supplements and more recently in some foods and beverages. In addition to the well-known flavonol glycosides and terpene lactones, G. biloba leaves are also rich in amino acids. To determine the content of free amino acids, a reliable method has been established by using hydrophilic interaction ultra-HPLC coupled with ESI-MS. 20 free amino acids were simultaneously determined without derivatization in 12 min. The proposed method was fully validated in terms of linearity, sensitivity, repeatability, as well as recovery. Furthermore, the principal component analysis was applied to different G. biloba leaves collected in November (after fruit harvest season), which revealed that the samples from different production areas exhibited regional disparity in different clusters in accordance with their various hydrophilic interaction chromatograms coupled with mass profiles. The established approach could be helpful for evaluation of the potential values as dietary supplements and the quality control of G. biloba leaves, which might also be utilized for the investigation of other medicinal herbs containing amino acids.