2.3. Elemental determination
Triplicate powder samples of each product were digested for
heavy metal analyses.100 mg of each triplicate was placed into
a Teflon PFA type digestion vessel and dissolved in 65%
HNO3 (Merck, Germany; Suprapur grade) using a microwave
sample preparation system (CEM Co. Model MDS-200) (Sahan
et al., 2007).