Abstract

The recently introduced amendment to the Consumer Goods Act in Germany concerns itself with the prohibition of the manufacture, marketing and import of consumer goods dyed with those azo dyes, which by cleavage of the azo bond(s) can liberate certain toxic listed aromatic amines. In many laboratory analytical methods the reduction of the azo bond is accomplished by treatment with sodium dithionite. However, using this strong reducing agent more than just the azo groups can be cleaved as specified in the German Act. In some cases even new amines can be generated which are neither part of the dye structure nor involved in the synthesis of the dye. These additional amines are formed by a side reaction due to the analytical procedure used and can thus lead to incorrect analytical results. The example reported here relates to the formation of 4—aminodiphenyl, when the diazo component is aniline.