Digestion
of candies and candy packages for heavy metal
analysis
Candy samples were digested with microwave-assisted
acid digestion. Samples were weighted to approximately
2.0 g in a vessel, to which 9.0 ml HNO3 and 1.0 ml H2O2 were
added. The temperature of the microwave instrument was
increased from room temperature to 200 C at 5 C min1
and held at this temperature for 15 min. After digesting,
the solution was gently heated to remove HNO3, and the residue
was then diluted to 10–20 ml with 0.5 mol l1 HNO3.
Sample blanks were performed with empty vessel, to which
9.0 ml HNO3 and 1.0 ml H2O2 were added.
Candy packages were digested using the dry ash method
(500 C, 6 h). Samples were weighted to approximately
0.2 g in ceramic crucible and diluted to 10–100 ml with
0.5 mol l1 HNO3 after digesting. Sample blanks were also
performed with empty ceramic crucible. Eight or nine Samples
and their blank were simultaneously analyzed as a
sample batch. All the solutions were assayed by ICP-OES
(Perkin–Elmer, Optima 5300DV, USA). The concentration
ranges for standard solutions were typically between 50
and 5000 lg l1