Standard additio--a way of improving quantification of banned azo dyes in leather.

An analytical procedure based on supercritical-fluid extraction and microwave-assisted extraction was applied on six different real leather samples for the determination of banned azo dyes. Determination of the dyes was performed indirectly by measuring their corresponding harmful aromatic amines, formed after reduction. A comparative study between external standard calibration and standard addition using both the dyes as well as the corresponding amines showed that the latter quantification method provided the highest accuracy.