On-line identification of depurinating DNA adducts in human urine by capillary electrophoresis-fluorescence line narrowing spectroscopy

The benzo[a]pyrene (BP)-derived 7-(benzo[a]pyren-6-yl)guanine (BP-6- N7Gua) depurinating one-electron oxidation adduct was identified in the urine extracts of coal-smoke-exposed humans for the first time. Urine samples were prepared by solid-phase extraction and reversed-phase high-performance liquid chromatography. Subsequently, the BP-6-N7Gua adduct was identified on-line with capillary electrophoresis fluorescence line narrowing spectroscopy (CE- FLNS) at 4.2 K. The daily excretion of BP-6-N7Gua in human urine of individuals exposed to coal smoke was approximately 226 pmol per μmol of creatinine. Due to the high level of excretion we propose that BP-6-N7Gua adducts found in urine could serve as effective biomarkers for risk assessment of BP exposure. The results demonstrate that CE-FLNS allows for on-line separation and DNA adducts identification in complex fluid extracts.