Pickering Laboratories has reported earlier that we developed and validated a post-column method for analysis of Theanine in tea (Camellia sinensis) dietary ingredients and supplements. Theanine is the main naturally occurring amino acid found in tea and it is responsible for a number of health benefits of tea as well as for its savory pleasant taste. 

The analytical method was developed in response to call for methods issued by Stakeholders Panel for Dietary Supplements. The method implements a simple extraction procedure without any clean-up steps and uses cation-exchange chromatography and post-column derivatization with Ninhydrin reagent to separate and detect Theanine.

Pickering method was approved by Expert Review Panel as AOAC First Action Official method for analysis if Theanine and can be implemented by laboratories for analysis if wide range of complex green tea-containing  dietary supplements in forms of powders, tablets, tinctures, gelcaps, sofgels and capsules.

The method and validation results are published in Journal of AOAC International:

J AOAC Int. 2016 Nov 1, 99(6), 1470-1478.

Maria Ofitserova, Sareeta Nerkar

Analysis of Theanine in Tea (Camellia sinensis) Dietary Ingredients and Supplements by High-Performance Liquid Chromatography with Postcolumn Derivatization: Single-Laboratory Validation, First Action 2016.10.