Pa. Limbach et al., MOLECULAR-MASS MEASUREMENT OF INTACT RIBONUCLEIC-ACIDS VIA ELECTROSPRAY-IONIZATION QUADRUPOLE MASS-SPECTROMETRY, Journal of the American Society for Mass Spectrometry, 6(1), 1995, pp. 27-39
The use of electrospray ionization mass spectrometry for the accurate
determination of molecular masses of polynucleotides and small nucleic
acids is developed. The common problem of gas phase cation adduction
that is particularly prevalent in the mass spectrometric analysis of n
ucleic acids is reduced through the use of ammonium acetate precipitat
ions and by the addition of chemical additives that compete for adduct
ions in solution. The addition of chelating agents such as trans-1,2-
diaminocyclohexane-N,N,N',N'-tetraacetic acid to remove divalent metal
ions and triethylamine to displace monovalent cations from the analyt
e, in conjunction with ammonium acetate precipitation, reduces cation
adduction to levels that permit accurate mass analysis (mass errors of
less than 0.01%) without further complex cleanup procedures. The pote
ntial utility of accurate mass measurements of small ribonucleic acids
is discussed.