Azo colorants that are able to form 4-aminoazobenzene, generate under the conditions of ISO 14362-1, the amines aniline and 1,4-phenylenediamine. The presence of these 4-aminoazobenzene colorants cannot be reliably ascertained without additional information (e.g. the chemical structure of the colorant used) or without a special procedure. ISO 14362-3:2017 is supplementary to ISO 14362-1 and describes a special procedure to detect the use, in commodities, of certain azo colorants, which may release 4-aminoazobenzene, and that are - accessible to reducing agent without extraction, particularly concerning textiles made of cellulose and protein fibres (e.g. cotton, viscose, wool, silk), and - accessible by extracting the fibres (e.g. polyester or imitation leather). For certain fibre blends, in 9.3 and 9.4 (with and without extraction) may need to be applied. The procedure also detects 4-aminoazobenzene (Solvent Yellow 1), which is already available as free amine in commodities without reducing pre-treatment. The use of certain azo colorants, which may release, by reductive cleavage of their azo group(s), one or more of the other aromatic amines listed in the Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) as regards Annex XVII, except 4-aminoazobenzene, cannot be determined quantitatively with this method.