Standardization An aliquot of 5 mL of a solution containing
up to 1.35 μg of Al3+ was transferred into a 10-mL volumetric
flask and its pH was adjusted to 4.50±0.05 by addition of
1 mL of the acetic/acetate buffer solutions. One milliliter of
1.0×10−4 M 3H2NA was added to it and diluted to the mark
with water. It was then shaken for 10 min and its fluorescence
intensity was measured (λex=366 nm, λem=460 nm).
Milk Samples Digestion The recommended procedure for
microwave digestion of samples is as follows: in treatment
with commercial milk samples, a portion of 100 mL of the
sample was placed in a porcelain dish and gently heated for
drying out of its liquid contents. The dried residue (≈8 g)was