The sample was mixed with a reagent containing
aluminum chloride and sodium nitrite, and a pink-colored
flavonoid-aluminum complex was formed in alkaline medium.
A solution corresponding to 30 l of sodium nitrite (10%), 60 l
of aluminum chloride hexahydrate (20%), 200 l of NaOH (1 M)
and 400 l of water was added to 100 l of each sample.