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Combined use of filtered and edited 1 H NMR spectroscopy to detect 13 C‐enriched compounds in complex mixtures
Author(s) -
Howe P. W. A.,
Ament Z.,
Knowles K.,
Griffin J. L.,
Wright J.
Publication year - 2012
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.2791
Subject(s) - xenobiotic , chemistry , nuclear magnetic resonance spectroscopy , isotope , nmr spectra database , phenacetin , radiochemistry , chromatography , stereochemistry , biochemistry , spectral line , enzyme , physics , quantum mechanics , astronomy
In conventional metabolism and pharmacokinetic studies, radioactive isotopes are used to identify and quantify the breakdown products of xenobiotics. However, the stable isotope 13 C provides a cheaper and less hazardous alternative. Metabolites of 13 C‐enriched xenobiotics can be detected, quantified and identified by 13 C‐filtered NMR spectroscopy. However, one obstacle to using 13 C is its 1.1% natural abundance that produces a background signal in 13 C‐filtered NMR spectra of crude biological extracts. The signal makes it difficult to distinguish between 13 C‐enriched xenobiotics resonances from endogenous metabolites unrelated to the xenobiotic. This study proposes that the 13 C background signal can be distinguished from resonances of 13 C‐enriched xenobiotics by the absence of a 12 C component in the xenobiotic. This is detected by combined analysis of 13 C‐filtered and ‐edited NMR spectra. The theory underlying the approach is described and the method is demonstrated by the detection of sub‐microgram amounts of 13 C‐enriched phenacetin in crude extracts of hepatocyte microsomes. Copyright © 2012 John Wiley & Sons, Ltd.