[Determination of theanine in tea leaves by HPLC-inhibited chemiluminescence with Co2+ catalyst].

A method for the separation and determination of theanine in tea leaves has been developed, based on inhibited chemiluminescence of cobalt-catalyzed luminol-H2O2 reaction by theanine. Separations were performed on a YWG-C18 column using a mobile phase of 0.01 mol.L-1 sodium acetate-acetic acid buffer at pH 5.5 at a flow rate of 0.8 mL.min-1. The optimum concentrations of Co2+, luminol, and H2O2 were 2 micrograms.L-1, 0.25 mmol.L-1, and 0.5 mmol.L-1, respectively. Under the conditions mentioned above, the relative peak area (Y) of inhibited chemiluminescence of theanine was linear with the concentration (X) of theanine in the range of 0.2 g.L-1-5.0 g.L-1 and its linear regression equation was Y = 33,862 x + 1.0605 (r = 0.9983). The average recovery was 97.82% with a RSD of 2.16%.