Analysis, Purification and Stability: Requirements for a Metabolism Study of an Azo Dye and Pigment

Abstract

Impurities of aromatic amines in the azo dye and pigment, Direct Black 38 and Pigment Yellow 12, and in vitro stability of the dye were determined. These factors can affect the results of studies designed to ascertain whether the two compounds are metabolized to potential carcinogens in hamsters. Procedures for removing impurities from the two compounds are also presented. Electron-capture gas chromatography of the heptafluorobutyryl derivatives of the impurities and degradation products was used to satisfy all the analytical requirements of the experiments. Major impurities found in Direct Black 28 were benzidine, 4-aminobiphenyl and 2,4-diaminoazobenzene; whereas, only 3,3'-dichlorobenzidine was found in Pigment Yellow 12. Stability studies of the purified dye conducted in water and in urine from hamsters and humans indicated that the dye would not degrade under the conditions used for collecting and assaying samples from a metabolism experiment. However, within 48 hours at 25 and 37.5 degrees C, the dye did degrade to known carcinogens in both hamster and human urine. Such degradation not only points out the need for proper storage of samples from metabolism studies but suggests that industrial effluents containing the dye should be properly treated before release into the environment.

Potent mutagenicity in the Ames test of 2‐cyano‐4‐nitroaniline and 2,6‐dicyano‐4‐nitroaniline, components of disperse dyes

“…Besides the possible toxicity of azo dyes per se [Yadav et al, ; Fernandes et al, ], these dyes can also present hazards mediated by their constituent aromatic amines. Residues of the amines used in synthesis may remain as impurities in the final dye product [Stavric et al, ; Nony and Bowman, ]. Furthermore, the aromatic amine components of the dyes may be liberated by the action of azoreductases, which can split the azo bond [Prival et al, ; Prival et al, ; Ryan et al, ; Feng et al, ; Mercier et al, ; Brissos et al, ].…”

Enhancement of Oxyanion and Diatrizoate Reduction Kinetics Using Selected Azo Dyes on Pd-Based Catalysts

“…Azo dyes were technical grade (percent purity is reported as available) and were purchased from Sigma-Aldrich (fast yellow AB 95% purity, congo red 91% purity), Acros (acid red 27 85% purity, metanil yellow 98% purity, methyl red, acid orange 7, acid yellow 11, acid yellow 17), Alfar-Aesar (methyl orange) or TCI (eriochrome black T). The primary impurities in azo dyes are their parent amines, based on study of direct black 38 and pigment yellow 12 ; small amounts of dispersants (e.g., polymers, surfactants) are also likely. We will show that amines of the azo dye MO do not affect reaction rate enhancement.…”

Ecologically friendly chitosan-montmorillonite bio-nanocomposite as adsorbent for textile dyes from aqueous solutions

“…It was found that there is a strong relationship between exposure to aromatic amines and risk to human cancer [1]. Since dyes have a high degree of chemical and photolytic stability [2] adsorption can be regarded as an appropriate method for dye removal prior their release into rivers, lakes etc. [3,4].…”