Electrospray ionization mass spectrometry of RNA nucleobases: Implications for solution chemistry and ion source operating conditions

The four common RNA nucleobases, cytosine, adenine, guanine and uracil, have been analyzed by electrospray ionization mass spectrometry. In light of the significant differences in the mass spectra obtained from each species, generalizations with respect to the effects of solution chemistry variables, such as pK, pH, solute concentration and solute solubility, are suggested. Electrospray source operating conditions, such as sample flow rate, electrostatic lens potentials, drying gas temperature and drying gas how rate, have been found to have substantial impact on the spectra as well. Of particular interest is the formation of nucleobase cluster species. The relative signal strength of these clusters seems to vary considerably with nucleobase type, solution chemistry and electrospray source operating conditions. (C) 1997 Elsevier Science B.V.