New methodology for the characterization of (±)-anti-BPDE-DNA adducts and tetrol I-1 with solid-matrix phosphorescence Original Research Article

Novel solid-matrix phosphorescence (SMP) methods were developed for the detection and characterization of (±)-anti-benzo[a]pyrene-trans-7,8-dihydrodiol-9,10-epoxide ((±)-anti-BPDE)-DNA adducts and a hydrolysis product of the (±)-anti-BPDE-DNA adducts, tetrol I-1, by using the heavy-atom salts, thallium nitrate and sodium iodide, to enhance the solid-matrix phosphorescence. Thallium nitrate was much more effective for enhancing the SMP of the (±)-anti-BPDE-DNA adducts and tetrol I-1. Thus, the results from TlNO3 were emphasized. The amount of TlNO3 adsorbed on the solid matrix was varied over a wide range, and SMP intensities, lifetimes, and spectra were acquired. Fundamental equations and calculated photophysical parameters were used to interpret the data and characterize the samples. The data indicated that there were two major populations of the (±)-anti-BPDE-DNA adducts and tetrol I-1 adsorbed on the solid matrix. Because DNA was adsorbed so strongly to the solid matrix, the (±)-anti-BPDE-DNA adducts interacted in a uniform manner with increasing amounts of TlNO3. However, tetrol I-1 responded in a more random fashion with the increase in the amount of TlNO3. The methods developed can be used to compare the SMP of small molecular-weight metabolites and DNA samples modified at different levels of (±)-anti-BPDE. Also, the methodology can be employed for DNA samples that are adducted with any material that would give measurable SMP.