Simultaneous measurement of 8-oxo-2 '-deoxyguanosine and 8-oxo-2 '-deoxyadenosine by HPLC-MS/MS

An assay with high selectivity and sensitivity has been developed which, fo r the first time, allows quantitative, simultaneous measurement in DNA of b oth 8-oxo-2'-deoxyguanosine (8-oxodG) and 8-oxo-2'-deoxyadenosine (8-oxodA) -important biomarkers of oxidative DNA damage in vivo. Using reversed-phase HPLC coupled to electrospray tandem mass spectrometry (HPLC-MS/MS) in mult iple reaction monitoring (MRM) mode it was possible to detect background le vels of these lesions in commercially available calf thymus DNA (85 +/- 3 a nd 7.1 +/- 0.2 per 10(6) DNA bases for 8-oxodG and 8-oxodA respectively; n = 3). Levels of 8-oxodG determined by HPLC coupled to an electrochemical de tection system (HPLC-EC) were found to be similar (75 +/- 6 per 10(6) DNA b ases; n = 3) to those obtained using tandem mass spectrometry. (C) 2000 Aca demic Press.