Amines, aromatic, leather

Separation of amines was realized in an ODS column (250 x 3 mm i.d. particle size 5 /tm) at 30°C. The flow rate was 0.3 ml/min and amines were detected at 280 nm. Solvents A and B for gradient elution were ACN and 3 mM phosphate buffer (pH = 7). The gradient started with 15 per cent A for 2 min then to 60 per cent A in 50 min. Chromatograms illustrating the separation of amines are shown in Fig. 3.72. It was established that the recoveries of both SFE and MAE were higher than those of traditional solvent extraction, therefore, their application for the analysis of carcinogenic aromatic amines in leather is highly advocated [140],... 

Most of the commercially available azo dyes do not break down to produce these forbidden amines. The European legislation which states that leather articles that come into contact with human skin should not contain any of the 22 aromatic amines in concentrations above 30 ppm can be found in Annex XVII [12] of REACH. Furthermore, most eco-labels and RSL have the same criteria. 

Several amino compounds are being used extensively in industrial processes. Most of these compounds are manufactured, except hydrazine. Azo dyes are produced by diazotization of aromatic amines and currently there are at least 3000 azo dyes in use. These dyes are used widely in textiles, leather, printing, paper making, drug and food industries. In the past three decades many food, drug and cosmetic colours have been banned from commercial use as food colourants. This section gives a brief account of adverse affects caused by the use of various amino compounds. 

The carcinogenic aromatic amines released from azo dyes in leather were investigated by using microwave-assisted extraction (MAE) or supercritical fluid extraction (SFE) followed by RP-HPLC. The chemical structures of dyes and aromatic amines are listed in Fig. 3.69. The flow schemes for SFE and MAE are shown in Figs 3.70. and 3.71. 

Hydrazone Dyes If the diazonium salts of aromatic amines are coupled with the methylene derivatives of N heterocycles, hydrazone dyes (i.e., the monoaza derivatives of the enamine dyes) are obtained. Paper and leather can be dyed in yellow to red shades with these dyes [23], They are moderately lightfast on polyacrylonitrile. If the diazo components contain substituents in the 2-position relative to the amino group that can form a hydrogen bond (e.g., 2-nitroaniline [24] or 1-ami-noanthraquinone [25]), lightfastness is improved considerably (10). 

In the case of aromatic amines as coupling components, one of the oldest azo dyes is C.I. Acid Yellow36, 13065 (1) 587-98-4], Because of the basic group suitable for salt formation the dye is not fast to acid, but it is still used today for dyeing wool and in special areas (leather and paper) primarily for price reasons. 

Initially, sulfur dyes were water-insoluble, macromolecular, colored compounds formed by treating aromatic amines and aminophenols with sulfur and/or sodium polysulfide. R. Vidal developed these dyes in 1893 but they only became attractive for leather with the introduction of water-solubilizing groups. Today, the sulfur dyes can be divided into three classes conventional water-insoluble, leuco, and solubilized sulfur dyes. Most sulfur dyes are synthesized by condensation of aromatic amines with sulfur or sodium polysulfide in the so-called bake process, or else in water or under pressure as a solvent-reflux reaction. 

Azo Compounds Azo dyes are widely used in the food, pharmaceutical, cosmetic, textile, and leather industry. They are synthetic compounds characterized by one (monoazo) or several intramolecular N = N bonds. Azo dyes, if they are systemically absorbed, can be metabolized by the way of azoreductases of intestinal microflora by liver cells and skin surface bacteria. This metabolism leads to aromatic amines that can be hazardous. In the 1930s, some azo derivatives like 4-dimethyl aminoazoben-zene (Butter Yellow, Cl Solvent Yellow 2, Cl 11020) and o-aminoazotoluene were experimentally found to be directly carcinogenic to liver and bladder after feeding. Other complex azo dyes like Direct Black 38 or Direct Blue 6 (Figure 28) release the aromatic amine benzidine. Some examples of azo dyes metabolized in benzidine and benzidine-congeners are listed in Table 3. 

Similar considerations apply to all aryl amine bladder carcinogens employed in the dye, rubber and leather industries51. Between 1930 and 1960, the toxic natures of many other coal-tar (aromatic) amino compounds, particularly azo dyes, were revealed52. 

To protect human health and improve consumer safety, the European Parliament and the Council of the European Union (EU) pubhshed Directives 2002/61/EC and 2003/3/EC on September 11, 2002 and January 6, 2003, respectively. These restrict the use of carcinogenic azo-dyes in textiles and leather articles and prohibits the sale of such articles dyed with the restricted azo dyes. Directives 2002/61/EC and 2003/3/EC had been transposed into national laws and put into effect in the member states respectively by September 11,2003 and June 30,2004. Aromatic amines (azo dyes) (22 kinds) specified and prohibited by Directive 2002/ 61/EC are listed in Table 3.3. 

Eskilsson, C. S., Davidsson, R., and Mathiasson, L., Harmful azo colorants in leather. Determination based on their cleavage and extraction of corresponding carcinogenic aromatic amines using modem extraction techniques, J. Chromatogr., 955, 215-227, 2002. 

Azo dyes which, by reductive cleavage of one or more azo groups, may release one or more of the aromatic amines listed in the Appendix in detectable concentrations, i.e. above 30 ppm in the finished articles or in the dyed parts thereof, may not be placed on the market or used in textile and leather articles which may come into direct and prolonged contact with the human skin or oral cavity, such as... 

This water-white, primary aliphatic amine is available commercially in an anhydrous form. It is soluble In water, methyl and ethyl alcohols, ethyl ether, ethyl acetate, aromatic and aliphatic hydrocarbons, acetone, mineral oil, fixed oils, oleic and stearic acids. It is soluble In hat paraffin and carnouba waxes, which solidify on cooling. It is potentially useful os on intermediate In such manufactured products as dyestuffs, surface-active agents, textile specialties, pharmaceuticals, bactericides, insecticides, and cleaning compounds. It is also used os o dehoiring ogent in the leather industry. 

Annex 1, No. 7 of the German Consumer Goods Ordinance, last amended 13 July 2005 [26] had unexpected repercussions in certain azo pigments. This entry banned the use of azo dyes which, on cleavage of one or more azo bonds would form any one of 22 Usted aromatic amines (see Table 23.6) in textiles and leather articles intended for more than temporary contact with the skin. The basis for the restriction is, that the restricted dyes are possible carcinogens, which is supported by the available test data. 

Standard methods for aromatic amines arising from the reductive cleavage of azo dyes have been established in Europe, such as the French norm AFNOR XP G08-014 for dyed textiles or the German method DIN 53316 for dyed leather (Pinheiro et al. 2004). 

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