Determination of theanine in tea-extraction by HPLC with a compensate after column and charged aerosol detection

An analytical method for the determination of theanine in tea-extraction by HPLC with compensate after column and charged aerosol detector(CAD)was developed.The results showed that the calibration formula was Y=0.1412X-0.0614,the correlation coefficient was above 0.9998,and the calibration curve was linear in the range of 1.50 ~ 50.0μg/mL,and the detection limit of the method(calculate with S/N=3)was 0.50μg/mL,and limit of quantitation was 1.50μg/mL(calculate with S/N=10).Then a sample was analyzed with this method,and the recoveries of blank sample spiked were 97.62% ~ 112.13%,and the difference of retention time was less than 0.2min and the relative standard deviation of peak area was 0.62%(n=5).The sensitive and accurate method was successfully applied to the analysis of theanine in tea-extraction.