| Abstract: | The fast-atom-bombardment mass spectra (FAB-MS) of a series of ribo- and deoxyribonucleosides and -nucleotides were examined in both positive-ion and negative-ion modes. Behaviour of cytosine analogs having unnatural bases (2(1H)-pyrimidone, 2(1H)-pyridinone, and 4-amino-2(1H)-pyridinone) was similar to that of compounds having naturally occurring bases. Nucleotides protected by dimethoxytrityl and p-chlorophenyl groups were also investigated using this technique. Use of negative-ion mode reduces interference from positive counter-ions (e.g., Na+) and allows rapid sequence determination of simple di- and trinucleotides. |
