Some synthetic dyes are sold with impurities making the
determination of the purity of these necessary. To determine purity,
100 mg of colorant is dissolved in 100 mL of purified water and
this has been taken as the reference solution. The percentage of
purity was calculated accordingly (Minioti, Sakellariou, &
Thomaidis, 2007). In this equation, the following variables are considered:
dilution factor of measured solution from standard solution;
absorbance of measure solution with reference to water;
concentration of reference solution; and specific absorbance of
aqueous solution of the colorant at 1% (w/v).