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 extr acts of coal-smoke-exposed humans for the first time. Urine samples were pr epared 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 (C E-FLNS) at 4.2 K. The daily excretion of BP-6-N7Gua in human urine of indiv iduals exposed to coal smoke was approximately 226 pmol per mu mol of creat inine. Due to the high level of excretion we propose that BP6-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 separa tion and DNA adducts identification in complex fluid extracts.