ABSTRACT
During the analysis of colored material it was found that certain atomic groups favor the absorption of light of certain wavelengths (selective absorption), and thus impart a color. Such atomic groups are called chromophores. The azo group (-N = N-) is one of the most important chromophore groups. They are the color carrier proper of azo colorants, during their disintegration discoloration occurs, e.g., by reduction agents which split the colorant molecule into two aromatic amines. Another chromophore group is the nitro group(-N02), linked to one or more benzene rings (1) systems of numerous conjugated double bonds also cause a colored appearance, as is shown in the example of betacarotene (2).
