An instrument will be developed for the mass spectral analysis of biomolecules which combines the best features of high flux particle bombardment (large secondary ion currents, the use of a liquid matrix and solution chemistry) and time-of-flight analysis (low cost and high ion transmission). High speed integrated transient recording will be used rather than the pulse counting techniques currently in use with plasma desorption and low flux SIMS time-of-flight configurations. The design will permit a direct comparison of the secondary ion spectra (molecular ions vs. fragmentation) under low and high primary ion flux conditions, with particular attention to the question of metastable decompositions from both methods. Time delayed ion extraction techniques, developed previously for laser desorption, will be used here to enhance high mass, low energy ion formation and focussing. The instrument will be applied to problems in biochemistry where rapid routine analysis can be undertaken under low (mass) resolution conditions, such as qualitative identification of molecular ions of peptides in hydrolysis mixtures, components of the lipid-A complex and mixtures of glycopeptides, or sequence changes in interspecies comparisons of epidermal growth factors. This proposal is identical with a proposal (GM 33967-01) submitted previously, except that: (1) results are reported on a feasibility study which demonstrates stable secondary ion currents on a time-of-flight using high flux primary beams (Section C), and (2) instrumental details are provided, based upon the use of a pulsed inert gas ion gun (Section D).
Showing the most recent 10 out of 23 publications
