Se content of different fractions from green tea was analyzed by atomic fluorescence spectroscopy [20]. The sample
was digested with 10 mL of a mixture of HNO3 and HClO4
(v/v, 4:1) at 120 ◦
C in a sand bath for 45 min. After cooling, 5 mL of 6 mol L−1
HCl was added to reduce Se6+
to Se4+ for 15 min. The digest was diluted with deionized
water to 50 mL. Then, 10 mL of the digest solution were
transferred to a reaction vessel and 2 mL of 6 mol L−1
HCl and 1 mL of 10% (w/w) K3
Fe(CN)3
were added. The
control in the same procedure was used to provide a blank
value.