HPLC radio-chromatogram (A) and UV chromatogram (348 nm) (B) of extracts from organic phase of media in A549 cells at 24 h. A549 cells (~5 × 106) were treated with 1,3-[3H2]-B[a]P-7,8-dione (2 µM, 1 × 105 cpm/nmol, 0.2 % (v/v) DMSO) in HBSS buffer containing 1 mM sodium pyruvate. The culture media were collected at 24 h, and subsequently acidified with 0.1% formic acid before extraction with ethyl acetate. The extracts were analyzed on a HPLC-UV-RAM.