Validation of a Densitometric Method for the Determination of Theanine in Tea Extracts Using CP Atlas Software

L-Theanine is a non-protein amino acid that occurs in the leaves of the tea plant (Camellia sinensis) and possesses several pharmacologic effects, and therefore it is widely applied in the food industry. Considering the chemical characteristics of the molecule (high polarity, lack of chromophore group), conventional HPLC-based methods are not optimal for the quantification of the compound. However, for TLC chromatographic separation of theanine in tea extracts, there are reliable methods available and TLC analysis allows derivatization for better detection of the compound. Here we report for the first time the development and validation of an eligible densitometric method based on the analysis of digital photographs of TLC plates without the need of densitometer and using a software available free of charge for the quick and reliable determination of theanine in tea extracts.