2.3.1. Preparation of resins
The commercial Amberlite XAD-7 resin (BDH),
a non-ionic macroreticular styrene divinylbenzene
copolymer, with 20–60 mesh size and 450m2 g−1
mean area was used to separate aluminum that bounds
to hydrolyzable polyphenols. The Amberlite XAD-7
resin was dried at 110C and ultrasonically washed
in methanol, 2M HNO3 and then water, respectively.
The washed resin was then immersed in an indium
solution at pH 5 for one night to saturate the cation
exchange sides. After pretreatment, Amberlite XAD-7
resin was transferred into small polyethylene columns
with a diameter of 1 cm [23].