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. Author manuscript; available in PMC: 2012 Oct 17.
Published in final edited form as: Chem Res Toxicol. 2011 Sep 14;24(10):1729–1734. doi: 10.1021/tx200262d

Figure 2.

Figure 2

Chromatograms obtained upon LC-NSI-HRMS/MS-SRM analysis of human leukocyte DNA (129 μg, 12.9 μg on column) containing 59.4 fmol/μmol Gua. The relatively higher amount of analyte in this sample allowed confirmation of its identity by additional monitoring of the accurate mass of the molecular ion of 7-ethyl-Gua and the internal standard. Panel (A) shows the result from monitoring of the accurate mass of 7-ethyl-Gua (m/z 180.08799). Panel (B) shows the result from the monitoring of the accurate mass of [15N5]7-ethyl-Gua (m/z 185.07317). Panel (C) shows the results from the transition at m/z 180 [M + H]+ → m/z 152.05669 [Gua + H]+ for 7-ethyl-Gua and panel (D) shows the corresponding transition m/z 185 [M + H]+ → m/z 157.04187 [Gua + H]+ for the internal standard. Results are shown with a 5 ppm mass tolerance.