Standard stock solutions of 1000 mg L1 for each individual
food colorant were prepared by dissolving approximately 25 mg
of unpurified colorant in 25 mL deionized water, taking into con-
sideration the purity of the colorant. The solutions were kept in
the fridge (4–8 C) for a maximum time period of 3 months.
Standard working solutions of 100 mg L1 were prepared by
appropriate dilution of the stock solutions in deionized water
and kept stable for 1 month at 4–8 C.