CHARACTERIZATION OF THE REACTION-PRODUCTS OF DEOXYGUANOSINE WITH THE ANTICANCER AGENT BFNU AND BFNU-1,1,1',1'-D4 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′‐d4 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. Copyright © 1990 John Wiley & Sons, Ltd.