Characterization of the reaction products of deoxyguanosine with the anticancer agent BFNU and BFNU‐1,1,1′, 1′ ‐ d 4 in different buffers by high‐performance liquid chromatography/atmospheric pressure ionization tandem mass spectrometry

The products of the reaction of the anticancer agent 1,3‐bis(2‐fluoroethyl)‐1‐nitrosourea (BFNU) and BFNU‐1,1,1′, 1′‐ d 4 with the DNA base deoxyguanosine were characterized by applying high‐performance liquid chromatography (HPLC)/tandem mass spectrometry. The total effluent from the HPLC column was introduced into the atmospheric pressure ionization (API) source of a triple‐quadrupole mass spectrometer via a heated nebulizer. The gasified mixture produced from the heated nebulizer was exposed to corona discharge ionization which led to generation of gas‐phase chemical ionization type of ions. The LC/API mass spectrometry produced ions and the tandem mass spectra allowed unambiguous identification, and assignment of positions of the deuterium atoms, in the products of the reaction under a variety of experimental conditions. The identification and characterization of a variety of 7‐(2′‐haloethyl)guanine derivatives among the reaction products provide confirmation of a proposed mechanism for the action of BFNU on DNA bases.