Novel LC-ESI/MS/MSn Method for the Characterization and Quantification of 2‘-Deoxyguanosine Adducts of the Dietary Carcinogen 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine by 2-D Linear Quadrupole Ion Trap Mass Spectrometry
An accurate and sensitive liquid chromatography-electrospray ionization/multi-stage mass spectrometry (LC-ESI/MS/MSn) technique has been developed for the characterization and quantification of 2‘-deoxyguanosine (dG) adducts of the dietary mutagen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (Ph...
Saved in:
Published in | Chemical research in toxicology Vol. 20; no. 2; pp. 263 - 276 |
---|---|
Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
American Chemical Society
19.02.2007
|
Online Access | Get full text |
Cover
Loading…
Summary: | An accurate and sensitive liquid chromatography-electrospray ionization/multi-stage mass spectrometry (LC-ESI/MS/MSn) technique has been developed for the characterization and quantification of 2‘-deoxyguanosine (dG) adducts of the dietary mutagen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). PhIP is an animal and potential human carcinogen that occurs in grilled meats. Following enzymatic digestion and adduct enrichment by solid-phase extraction (SPE), PhIP−DNA adducts were analyzed by MS/MS and MSn scan modes on a 2-D linear quadrupole ion trap mass spectrometer (QIT/MS). The major DNA adduct, N-(deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (dG-C8-PhIP), was detected in calf thymus (CT) DNA modified in vitro with a bioactivated form of PhIP and in the colon and liver of rats given PhIP as part of the diet. The lower limit of detection (LOD) was 1 adduct per 108 DNA bases, and the limit of quantification (LOQ) was 3 adducts per 108 DNA bases in both MS/MS and MS3 scan modes, using 27 μg of DNA for analysis. Measurements were based on isotope dilution with the internal standard, N-(deoxyguanosin-8-yl)-2-amino-1-(trideutero)methyl-6-phenylimidazo[4,5-b]pyridine (dG-C8-[2H3C]-PhIP). The selected reaction monitoring (SRM) scan mode in MS/MS was employed to monitor the loss of deoxyribose (dR) from the protonated molecules of the adducts ([M + H − 116]+). The consecutive reaction monitoring (CRM) scan modes in MS3 and MS4 were used to measure and further characterize product ions of the aglycone ion (BH2 +) (Guanyl-PhIP). The MS3 scan mode was effective in eliminating isobaric interferences observed in the MS/MS scan mode and resulted in an improved signal-to-noise (S/N) ratio. Moreover, the product ion spectra obtained by the MSn scan modes provided rich structural information about the adduct and were used to corroborate the identity of dG-C8-PhIP. In addition, an isomeric dG-PhIP adduct was detected in vivo. This LC-ESI/MS/MSn method is the first reported application on the use of the MS3 scan mode for the analysis of DNA adducts in vivo. |
---|---|
Bibliography: | istex:D9374DC26BE74E51BDA9B088C2F6586A900E1B5E ark:/67375/TPS-K126WVWF-V Formerly Angela K. Brock. To whom correspondence should be addressed. Phone: 518-474-4151. Fax: 518-486-1505. E-mail: rturesky@wadsworth.org. NYS Department of Health. University of Toledo College of Medicine. |
ISSN: | 0893-228X 1520-5010 |
DOI: | 10.1021/tx0601713 |