Electronic spectral parameters of the azo indicators: methyl red, methyl orange, PAN, and fast black K-salt

The electronic absorption spectra of some azo indicators (methyl red, methyl orange, PAN, and fast black K-salt) were taken in different solvents with different physical properties in order to study the solvent-solute interaction. The parameters used depend on the solvent dielectric constant and refractive index. The data are analyzed based on multiple regression technique.