beverage samples
were subjected to wet digestion. The steps of this process are as
follows. (i) 15 mL of beverage samples were transferred to a
100 mL conical flask, and treated with a mixture of HNO3 and
H2O2 (2:1, v/v). (ii) This mixture was carefully heated on a hot plate
for 3 h at 120 C and maintained until the complete decomposition
of sample was achieved. (iii) Afterwards, the mixture was cooled
and filtered by membrane filter of 0.45 lm.