Analysis of DNA-adducts in DNA hydrolysates by capillary zone electrophoresis and capillary zone electrophoresis electrospray mass-spectrometry

The in vitro adduct formation with phenyl glycidyl ethers (PGEs) was studied on 2'-deoxynucleotides and DNA. The modified DNA was hydrolyzed enzymatically, and the mixtures consisting of unmodified 2'-deoxynucleotide adducts were analyzed by capillary zone electrophoresis (CZE), CZE-electrospray mass spectrometry (CZE/ES-MS) and CZE-electrospray tandem mass spectrometry (CZE/ES-MS/MS) using sample stacking. For the CZE analyses, a homemade system was developed in order to enhance the reproducibility of the retention times. This modification enabled the total comparison of the electropherograms obtained for the analysis of 2'deoxynucleotides mixtures with the electropherograms obtained for the DNA hydrolysates both treated with PGEs. The assignment of adducted and nonadducted 2'-deoxynucleotide peaks was unambiguous. Analysis of the CZE/ES-MS data gave the necessary structural information and revealed the presence of mono- and dialkylated 2'-deoxynucleotides. Interpretation of the CZE/ES-MS/MS data of the monoalkylated products allowed differentiation between purine or pyrimidine alkylation and alkylation of the 5-phosphate moiety. Recording of full-scan mass spectra during CZE/ES-MS/MS analysis of 2'-deoxynucleotide reaction mixtures and DNA hydrolysates was possible, using the described CZE sample stacking technique.