Analysis of Amino Acids by Ultra High Performance Liquid Chromatography-Electrospray Ion Tandem Mass Spectrometry Using 4-Nitrobenzoyl Chloride as Precolumn Derivatization

A pre-column derivatization method for determination of amino acids in tobacco leaves by ultra-high performance liquid chromatography-electrospray ion tandem mass spectrometry using 4-nitrobenzoyl chloride as derivatization reagent was developed. The sample was extracted by ultrasound-assisted extraction, and then the extracts were rapidly derived with 4-nitrobenzoyl chloride. The derivative reaction was performed in NH4HCO3-NH3 center dot H2O buffer solution at pH 9. 0 and room temperature with oscillation assistance for 1 min. To enhance the sensitivity, the parameters of multiple reaction monitoring were also optimized. This method had many advantages including mild reaction condition , simple procedure and short derivatization time. The method showed a good linearity with correlation coefficients of 0. 9951-0. 9998. The detection limits were 0.56-2. 00 mu g/L with RSDs of 0. 5%-8. 0%. This method coupled with multivariate statistical analysis method was successfully employed for determination of amino acids in tobacco leaves from three different geographical origins, showing a good classification results.