Objective: To establish a quantitative method for the free amino acids in Notoginseng Radix et Rhizoma. Method: Hydrophilic interaction chromatography-tandem mass spectrometry was used to determine the 22 amino acids in Notoginseng Radix et Rhizoma. An ACQUITY UPLC BEH amide column (2.1 mm×100 mm

1.7 μm) was applied for the separation of these amino acids with a gradient mobile phase consisting of solution A (water

5 mmol·L-1 ammonium formate

5 mmol·L-1 ammonium acetate and 0.15% formic acid) and solution B (acetonitrile

1 mmol·L-1 ammonium formate

1 mmol·L-1 ammonium acetate and 0.05% formic acid) at a flow rate of 0.4 mL·min-1. The linear gradient conditions were as follows:0-6 min

15%-20% A;6-10 min

20%-30% A;10-12 min

30%-46% A. The column temperature was maintained at 35 ℃. Multiple reaction mode detection (MRM) in positive ion mode was used in this assay. Result: Good separation of the 22 amino acids was obtained within 12 min. Good correlations were found between the investigated compounds concentrations and their peak areas within the test ranges with the correlation coefficient from 0.991 7 to 0.999 9.The average recoveries were from 93.7% to 104.7%. The overall intra-and inter-day variations (RSDs) based on the peak areas of the analyte were in the range of 1.13%-4.95% and 1.84%-5.62% respectively. The total content of 22 free amino acids in 10 batches samples of Notoginseng Radix et Rhizoma was from 4.72 mg·g-1 to 5.96 mg·g-1. Conclusion: The proposed method is simple

rapid

sensitive and suitable for the determination of amino acids in Notoginseng Radix et Rhizoma and could provide the basis for Notoginseng Radix et Rhizoma quality control.