Quick extraction and direct determination of amino acids from plants by hydrophilic interaction liquid chromatography (HILIC) and high-performance liquid chromatography-mass spectrometry without derivatization

Amino acids are naturally compound in many plants and have a essential effects on human life. This work presents a simple and rapid analytical method for direct determination of amino acids without derivatization. The preparation method of samples was green and quick, which extracted amino acids with water in 10 min, and separated on a HILIC-Z (2.1 mm×100 mm, 2.7 μm i.d.) using acetonitrile-water solution as mobile phase, and then detected under ESI-multiple reaction monitoring mode. Satisfactory determination of 21 underivatized amino acids from three different plants was achieved in 15 min. This method showed a good linearity (R2 > 0.99) for the analyst and the detection limits (LOD) were 0.53 mg/kg–10.39 mg/kg for the amino acids. The average recoveries were in the range of 80%–120% at spiked concentrations. The analytical method is high sensitivity, accuracy and analytical efficiency, meanwhile it may be used for the analysis of amino acids in other plants.