scholarly journals Evaluating the utility of ion mobility separation in combination with high-pressure liquid chromatography/mass spectrometry to facilitate detection of trace impurities in formulated drug products

2007 ◽  
Vol 21 (7) ◽  
pp. 1255-1263 ◽  
Author(s):  
Christine Eckers ◽  
Alice M.-F. Laures ◽  
Kevin Giles ◽  
Hilary Major ◽  
Steve Pringle
Keyword(s):  
Mass Spectrometry ◽  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Ion Mobility ◽  
Liquid Chromatography Mass Spectrometry ◽  
Trace Impurities ◽  
Mobility Separation ◽  
Drug Products ◽  
Ion Mobility Separation

scholarly journals A Novel Metabolic Pathway for Degradation of 4-Nonylphenol Environmental Contaminants bySphingomonas xenophagaBayram

2005 ◽  
Vol 280 (16) ◽  
pp. 15526-15533 ◽  
Author(s):  
Frédéric L. P. Gabriel ◽  
Andy Heidlberger ◽  
Daniel Rentsch ◽  
Walter Giger ◽  
Klaus Guenther ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Resonance Spectroscopy ◽  
Growth Substrate ◽  
Liquid Chromatography Mass Spectrometry ◽  
Hydrogen Atoms ◽  
Chromatography Mass Spectrometry ◽  
Sphingomonas Xenophaga

Several nonylphenol isomers with α-quaternary carbon atoms serve as growth substrates forSphingomonas xenophagaBayram, whereas isomers containing hydrogen atoms at the α-carbon do not (Gabriel, F. L. P., Giger, W., Guenther, K., and Kohler, H.-P. E. (2005)Appl. Environ. Microbiol.71, 1123–1129). Three metabolites of 4-(1-methyloctyl)-phenol were isolated in mg quantities from cultures of strain Bayram supplemented with the growth substrate isomer 4-(1-ethyl-1,4-dimethyl-pentyl)-phenol. They were unequivocally identified as 4-hydroxy-4-(1-methyl-octyl)-cyclohexa-2,5-dienone, 4-hydroxy-4-(1-methyl-octyl)-cyclohex-2-enone, and 2-(1-methyl-octyl)-benzene-1,4-diol by high pressure liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy. Furthermore, two metabolites originating from 4-n-nonylphenol were identified as 4-hydroxy-4-nonyl-cyclohexa-2,5-dienone and 4-hydroxy-4-nonyl-cyclohex-2-enone by high pressure liquid chromatography-mass spectrometry. We conclude that nonylphenols were initially hydroxylated at theipso-position forming 4-alkyl-4-hydroxy-cyclohexa-2,5-dienones. Dienones originating from growth substrate nonylphenol isomers underwent a rearrangement that involved a 1,2-C,O shift of the alkyl moiety as a cation to the oxygen atom of the geminal hydroxy group yielding 4-alkoxyphenols, from which the alkyl moieties can be easily detached as alcohols by known mechanisms. Dienones originating from nongrowth substrates did not undergo such a rearrangement because the missing alkyl substituents at the α-carbon atom prevented stabilization of the putative α-carbocation. Instead they accumulated and subsequently underwent side reactions, such as 1,2-C,C shifts and dihydrogenations. Theipso-hydroxylation and the proposed 1,2-C,O shift constitute key steps in a novel pathway that enables bacteria to detach α-branched alkyl moieties of alkylphenols for utilization of the aromatic part as a carbon and energy source.

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