A fixed concentration of GA was spiked in every sample as an IS before analysis, in order to verify the reproducibility of the assay. The concentration of the IS was determined in control tablets using the calibration curve of GA (Table 3). Determination of EGCG was achieved only if the recovery % of the IS was within acceptable limits (95–105%), as shown in Table 3. The assay was considered superior to previously reported HPLC methods, with respect to its ability to compensate for matrix interference, obviate the need for a standard of EGCG, its short analysis time and minimal mobile phase consumption. The TLC–densitometric assay does not require either preconditioning of the stationary phase or lengthy washing steps that are often required when analysing natural products in particular.