Solvent influence on absorption spectra of food azo dyes

Abstract

The solvent influence on absorption spectra of food azo dyes was examined by the method of Linear Solvation Energy Relationships (LSER). For this purpose, six azo dyes were used: tartrazine (E 102), ponceau 4R (E 124), azorubin (E 122), brilliant black (E 151), amaranth (E 123) and gelb orange S (E 110). Absorption spectra of dissolved azo dye have been recorded in the wavelength range of visible radiation, or from 380 to 760 nm, in eight solvent of different polarity. The choice of the solvent was limited due to the high polarity of the azo dye molecules themselves. The effect of solvent dipolarity/polarizability and solvent/solute hydrogen bonding interaction are analysed by means of the linear solvation energy relationship (LSER) concept proposed by Kamlet and Taft. The linear correlation of the absorption maxima with parameters of Kamlet-Taft solvatochrome equation yielded satisfactory results.