Ultrasensitive UPLC-MS-MS Method for the Quantitation of Etheno-DNA Adducts in Human Urine

Etheno-DNA adducts are generated from the metabolism of exogenous carcinogens and endogenous lipid peroxidation. We and others have previously reported that 1,N6-ethenodeoxyadenosine (edA) and 3,N4-ethenodeoxycytidine (edC) are present in human urine and can be utilized as biomarkers of oxidative stress. In this study, we report a new ultrasensitive UPLC-ESI-MS/MS method for the analysis of edA and edC in human urine, capable of detecting 0.5 fmol edA and 0.3 fmol edC in 1.0 mL of human urine, respectively. For validation of the method, 20 human urine samples were analyzed, and the results revealed that the mean levels of edA and edC (SD) fmol/µmol creatinine are 5.82 ± 2.11 (range 3.0–9.5) for edA and 791.4 ± 328.8 (range 116.7–1264.9) for edC in occupational benzene-exposed workers and 2.10 ± 1.32 (range 0.6–4.7) for edA and 161.8 ± 200.9 (range 1.8–557.5) for edC in non-benzene-exposed workers, respectively. The ultrasensitive detection method is thus suitable for applications in human biomonitoring and molecular epidemiology studies.