Characterization of sulfonated azo dyes and aromatic amines by pyrolysis gas chromatography/mass spectrometry
- 447 Downloads
Sixteen sulfonated and unsulfonated azo dyes as well as eleven sulfonated and unsulfonated aromatic amines were analyzed and qualitatively characterized by means of pyrolysis gas chromatography/mass spectrometry at different temperatures. Aniline and aminonaphthalene were found to be the dominant pyrolysis products of sulfonated aromatic amines and dyes. Azo dye and dye class specific key compounds such as benzidine, vinyl-p-base and 4-aminoazobenzene could be identified by pyrolysis gas chromatography/mass spectrometry of commercial acid, cationic, direct, reactive and solvent dyes. 500 °C was the optimal pyrolysis temperature for most of the pyrolyzed compounds. The method was applied to a dried sample of a textile wastewater concentrate from a dyeing process. Reactive azo dyes of the group of Remazol dyes and anthraquinone dyes could be identified as the major compounds of the sample. The finding of caprolactam (a printing additive) suggests that the wastewater contained effluent from a process of heat-activated printing with reactive dyes. p-Chloraniline, a banned aromatic amine, was identified. Chemical reduction of the wastewater sample prior to pyrolysis resulted in the release of volatile aromatic amines and aided the classification of several products of pyrolysis.
KeywordsPyrolysis GC–MS Thermal extraction Sulfonated azo dyes Aromatic amines
We thank Dr. Konrad Bootz from DyStar GmbH, Leverkusen, Germany for kindly providing dyes and dye educts. We owe much gratitude to Ruth Meurer for supporting the performance of Py-GC MS analyses.
- 1.Zollinger H (1991) Color chemistry, 2nd edn. VCH, New York, p 1Google Scholar
- 2.DyStar (2000) German legislation on azo dyes, 2nd issue. DyStar GmbH, Leverkusen, GermanyGoogle Scholar
- 3.EC (2006) Directive 2002/61/EC of the European Parliament and of the Council of 19th July 2002. Off J Eur Commun L243:15Google Scholar
- 4.Reisch MS (1996) Chem Eng News 10Google Scholar
- 5.Correia VM, Stephenson T, Judd SJ (1994) Environ Technol 15:917–929Google Scholar
- 6.Wampler TP (ed) (1995) Handbook of pyrolysis. Marcel Dekker, New York, Ch 1Google Scholar
- 7.Saferstein R, Manura JJ (1977) J Forensic Sci 22:748Google Scholar
- 8.DeFelippi J, Kenion G, Ludicky R (1995) In: Proc 43rd ASMS Conf on Mass Spectrometry and Allied Topics, 21–26 May 2005, Atlanta, GAGoogle Scholar
- 20.Wagner B, Xu M (2004) Reactive dye printing process. US Patent 20040219296Google Scholar