Detection and determination of aromatic amines as products of reductive splitting from selected azo dyes.

The current environment-friendly regulations concerning textile products ban the marketing of textiles dyed with azo dyes capable of reductively splitting carcinogenic aromatic amines. The study analyzes seven azo dyes whose chemical structure determines various quantities of splitting aromatic amines, such as benzidine. For tests, seven commercially available azo dyes with aromatic amines in their structure were selected. These included two hazardous dyes: Acid Red 85 and Direct Blue 6, both capable of reductively splitting carcinogenic benzidine. Of the remaining five azo dyes, three--Ponceau SS, Sudan II, and Disperse Yellow 7--are capable of splitting p-phenylenediamine and aniline, while Mordant Orange 1 and Disperse Orange 3 can split only p-phenylenediamine. For Acid Red 85 and Direct Blue 6, the quantity of benzidine split from them was analyzed, depending on the conditions of the reduction process (e.g., in the HPLC method, 104 g/kg of dye for reduction in NaOH, and 41 g/kg of dye for reduction in acetate buffer). The spectrophotometric method proved useful for preliminary analysis of amine content in examined samples. Spectrophotometric analysis may be used to determine the total content of amines counted as aniline. A full qualitative and quantitative analysis of amines released from azo dyes is possible using high-performance liquid chromatography (HPLC).

Semiempirical infrared spectra simulations for some aromatic amines of interest for azo dye chemistry.

A set of semiempirical methods (PM3, AM1, MNDO, MNDO3, INDO, CNDO and ZINDO/1) has been tested to find the best tool for the identification of aromatic amines by infrared spectroscopy. Analysed were 1,4-, 1,3-, 1,2-phenylenediamines and aniline, amines commonly used in the dye industry. Of all the semiempirical methods tested, AM1 showed the closest correspondence to experimental values. It provided the best linearity between the calculated and experimental frequencies (correlation coefficient, cc = 0.9993). In the range of -NH2 stretching vibrations, the best correspondence between the theoretical and experimental frequencies was achieved for the PM3 method (cc = 0.8369).

The evaluation of structural changes in wool fibre keratin treated with azo dyes by Fourier Transform Infrared Spectroscopy.

Fourier Transform Infrared Spectroscopy spectroscopy is a useful technique for the analysis of structural changes in wool fibres at the molecular and supermolecular levels. Ecological requirements the textile industry has to meet oblige manufacturers to use ecological dyes in the process of fibre dyeing. These dyes should not split into the forbidden, carcinogenic aromatic amines (e.g. benzidine) while used. Wool was dyed with an azo dye, then underwent a chemical reaction. Changes were observed in the region of Amide A, Amide B, Amide I and II, dipolar ions amino acids, and the fingerprint region.