Stability and reproducibility of green tea extract
Green tea extract in acetate buffer was prepared and left for 1,
2, 3, 4, 24, 48 and 72 h before mixing with Fe(II) and Fe(III)
solutions (10 and 100 ppm) at the ratio of 1:1 (10 ml extract:
10 ml Fe solution). Absorbances of the mixture were recorded
after mixing for 30 and 45 min at 560 nm against acetate buffer
using a Spectronic 21 (Spectronic Instrument). Absorbance of
green tea extract alone was also recorded to ensure that the
absorbance of the extract did not change significantly with time,
since such a change might interfere with the absorbance of the