Abstract: A method for simultaneous analysis of 20 free amino acids in tobacco was developed using liquid chromatography-electrospray ionization/ion trap tandem mass spectrometry (LC-ESI-IT-MS/MS). Tobacco samples were extracted and filtered, and analyzed without derivatization or solid phase extraction. The LC separation was carried on a reversed-phase HyPURITY C18 column (200 mm×2.1 mm, 5 μm) with the mobile phase of 1%(v/v) acetonitrile/water solution containing 0.1% nonafluoropentanoic acid and 90% acetonitrile/water solution containing 0.1% nonafluoropentanoic acid in gradient mode. The results showed that the limits of detection (LODs) of 20 amino acids were in the range of 0.01-0.05 μmol/L (S/N=3), the linear correlation coefficients were above 0.9977 in all cases, and the relative standard deviations (RSDs) of peak areas of the extracted ion chromatograms were in the range of 0.78%-4.93%. The developed method is of good efficiency, sensitivity and selectivity, and has been successfully applied to determine the free amino acids in varieties of tobacco samples.

Key words: free amino acids, liquid chromatography-tandem mass spectrometry (LC-MS/MS), tobacco