Characterization of DNA adducts from lung tissue of asphalt fume-exposed mice by nanoflow liquid chromatography quadrupole time-of-flight mass spectrometry

Abstract

A bioanalytical method based on nanoflow liquid chromatography coupled to a hybrid quadrupole orthogonal acceleration time-of-flight mass spectrometry was developed to characterize selected polyaromatic hydrocarbon (PAH)–DNA adducts. The collision-induced dissociation of analytes results in characteristic fragmentation patterns that can be utilized to identify the DNA adducts. In the experiment, 32 B6C3F1 mice were exposed daily (4 h/day) to asphalt fume in a whole-body inhalation chamber for 10 days; 16 nonexposed mice served as controls. The asphalt fume was generated at 180 °C and the concentrations of PAHs in the animal exposure chamber ranged from 152 to 198 mg/m 3. The DNA adducts N 2-deoxyguanosine-benzo( a)pyrene-7,8-dihydrodiol-9,10-epoxide ( N 2-dG-BPDE); N 6-deoxyadenosine-benzo( a)pyrene-7,8-dihydrodiol-9,10-epoxide ( N 6-dA-BPDE), and N 4-deoxycytidine-benzo( a)pyrene-7,8-dihydrodiol-9,10-epoxide ( N 4-dC-BPDE) were identified. The concentrations of N 2-dG-BPDE, N 6-dA-BPDE, and N 4-dC-BPDE adducts were determined to be 1.17, 0.97, and 0.68 pmol/mg DNA, respectively, in the lung tissue of exposed mice using the nanoflow technique. The total DNA adducts in exposed lung tissue was determined to be 8.35 pmol/mg DNA by 32P-postlabeling assay. In total, the results indicated that PAH–DNA adducts were significantly elevated ( p<0.001) in the lung tissue of asphalt-fume-exposed mice relative to tissue from control animals.