Nevertheless, from the results, we may conclude that both
Fe(II) and Fe(III) could form color complexes with green tea
extract and that Fe(III)-green tea complex has higher molar
absorptivity. Therefore, in order to obtain the best sensitivity
when applying the system with real samples, Fe(III) was chosen
as a standard to form complex with green tea extract in acetate
buffer pH 4.8, for the construction of calibration/standard
addition graphs