Quantification of Etheno-DNA adducts using liquid chromatography, on-line sample processing, and electrospray tandem mass spectrometry

Etheno-DNA adducts are promutagenic lesions present in normal animal and hu man tissues that are believed to be important in the etiology of cancer rel ated to diet and lifestyle. A method has been developed for the quantificat ion of trace levels of etheno-DNA adducts using on-line sample preparation coupled with liquid chromatography and electrospray tandem mass spectrometr y. The use of automat ed solid-phase extraction and stable labeled internal standards permitted the robust determination of ethenodeoxyadenosine conta ined in crude DNA hydrolysates from untreated rodent and human tissues at l evels on the order of one adduct in 10(8) normal nucleotides from 100 mug o f DNA. Inherent analyte response and matrix interference made sensitivity f or simultaneous determination of ethenodeoxycytidine approximately 5-fold l ower. The method was applied to the analysis of liver DNA from untreated an d urethane-treated B6C3F1 mice, untreated rat liver, human placenta, and se veral commercial DNA preparations. Some sources of potential artifactual fo rmation of etheno-DNA adducts were investigated.