Detection of methylquinoline transformation products in microcosm experiments and in tar oil contaminated groundwater using LC-NMR

• Published in: Chemosphere (Oxford) 2008-02, Vol.70 (11), p.2118-2126
• Main Authors: Reineke, Anne-Kirsten, Preiss, Alfred, Elend, Manfred, Hollender, Juliane
• Format: Article
• Language: English
• Subjects: Anaerobiosis; Applied sciences; Biodegradation; Biotransformation; Chromatography, High Pressure Liquid; Coal Tar; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Groundwater; Groundwaters; Hydroxylation; LC-NMR; Magnetic Resonance Spectroscopy; Metabolites; Methylation; Methylquinolines; Natural water pollution; Oxidation-Reduction; Pollution; Pollution, environment geology; Quinolines - analysis; Quinolines - metabolism; Tar oil; Water Microbiology; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - metabolism; Water Supply - analysis; Water treatment and pollution
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2007.08.061

N-heterocyclic compounds are known pollutants at tar oil contaminated sites. Here we report the degradation of methyl-, and hydroxy-methyl-substituted quinolines under nitrate-, sulfate- and iron-reducing conditions in microcosms with aquifer material of a former coke manufacturing site. Comparison of degradation potential and rate under different redox conditions revealed highest degradation activities under sulfate-reducing conditions, the prevailing conditions in the field. Metabolites of methylquinolines, with the exception of 2-methylquinolines, were formed in high amounts in the microcosms and could be identified by 1H NMR spectroscopy as 2(1H)-quinolinone analogues. 4-Methyl-, 6-methyl-, and 7-methyl-3,4-dihydro-2(1H)-quinolinone, the hydrogenated metabolites in the degradation of quinoline compounds, were identified by high resolution LC-MS. Metabolites of methylquinolines showed persistence, although for the first time a transformation of 4-methylquinoline and its metabolite 4-methyl-2(1H)-quinolinone is described. The relevance of the identified metabolites is supported by the detection of a broad spectrum of them in groundwater of the field site using LC-NMR technique. LC-NMR allowed the differentiation of isomers and identification without reference compounds. A variety of methylated 2(1H)-quinolinones, as well as methyl-3,4-dihydro-2(1H)-quinolinone isomers were not identified before in groundwater.