Application of MALDI and PSD to the structure determination of adducts between DNA bases and the carcinogen 7H-dibenzo[c,g]carbazole

Dibenzo[c,g]carbazole is the first heterocyclic aromatic compound that is known to be activated by one-electron oxidation; the resulting radical cation intermediate reacts with DNA to form adducts. We synthesized reference DNA adducts and studied them by MALDI and PSD, as well as by four-sector tandem mass spectrometry. The information content of PSD product-ion spectra compares favorably with those obtained by FAB or ESI and tandem sector mass spectrometry. The small differences that do occur are attributable to energy differences between the methods of ionization. We also assessed the reproducibility of PSD spectra using a statistical test called the 'similarity index' and found them to be as reproducible as product-ion spectra obtained on a four-sector tandem mass spectrometer. (C) 1997 Elsevier Science B.V.