Detection of methylquinoline transformation products in microcosm experiments and in tar oil contaminated groundwater using LC-NMR.
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 (1)H 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.
Reineke
Anne-Kirsten
AK
Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.
Preiss
Alfred
A
Elend
Manfred
M
Hollender
Juliane
J
D000693:Anaerobiosis; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D003033:Coal Tar; D006900:Hydroxylation; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D010084:Oxidation-Reduction; D011804:Quinolines / Q000032:analysis / Q000378:metabolism*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*; D014881:Water Supply / Q000032:analysis*
D011804:Quinolines; D014874:Water Pollutants, Chemical; D003033:Coal Tar