Determination of Banned Azo Dyes in Leather

Sammanfattning: Dyes are commercially indispensable and the expanding industry offers a complete palette of colors. Azo dyes constitute the largest chemical class of synthetic dyes because of their versatility, low price, and ease of production. These dyes may, however, pose health risk to humans due to formation of mutagenic/carcinogenic aromatic amines upon reductive cleavage of their azo groups (-N=N-). Therefore, the EU has introduced a ban on the marketing and use of certain azo dyes in textile and leather goods. The appended papers present analytical procedures for determination of banned azo dyes in leather. The main foci in the development of these procedures was enhancement of sample preparation by employing diverse instrumentation-based techniques, including supercritical-fluid extraction (SFE), microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), and stir-bar sorptive extraction (SBSE). Despite extensive optimization, inaccurate results were obtained when quantification was performed by means of common external standard calibration. Standard additions of the corresponding azo dyes turned out to be a feasible way to tackle the problem with systematic errors. However, the usefulness of the developed standard addition methodology relies on knowledge of, and access to, the azo dyes present in the leather. Nevertheless, all developed procedures proved superior, in terms of accuracy, to the prevailing German standard (i.e. DIN 53316) regardless of quantification method employed.