equally divided into eight parts and each part was transferred
into one of the microwave digestion vessel. After adding 2 mL
of H2O2 at 30%and 8 mL of HNO3 at 65%to each one of the
vessels, they were closed and fastened into the eight-port rotor.
The process of digestion and mineralization using the microwave
oven containing the rotor with eight loaded vessels was
performed according to the recommended program as detailed
in Table 1. In treatment with powder milk samples, portions
of 1 g were weighted and subjected to the above
procedure, similarly. The dryness digested samples were
then treated with aliquots of 8 mL of 0.1 M Na2CO3 to
separate almost of their Ca2+, Mg2+, and Fe3+ contents as
either carbonate or hydroxide precipitates. After filtration,
the resultant solutions were acidified with acetic
acid and then heated to remove the excess amounts of
carbonate as carbonic anhydride. By addition of a few
drops of ammonia to the solution, its pH was adjusted to
4.5 and then followed the Al3+ determination procedure.