<title>New methods to sequence DNA by mass spectrometry</title>

Preliminary work on a new approach to sequencing polynucleotides by the Sanger procedure is presented. The method is based on a mass spectrometric determination of the four component terminal nucleotide residues, where the information regarding the identity of the individual nucleotides is contained in the mass of a stable nuclide marker. Specifically, the four stable isotopes of sulfur (32, 33, 34, 36) will be used to identify the four terminal bases (A, T, G, C ) where the label is incorporated as a thiophosphate bridge. The nucleotide fragments are separated by capillary electrophoresis. The identity of the isotope marker for the terminal base is then determined by combustion, and mass spectrometric analysis of the resulting isotopically labeled sulfur dioxide.