The five presentations made in the workshop are summarized here. The general operational concepts of the LDMS method were reviewed, emphasizing results obtained from linear analysis, from reflectron analysis, and by using post source decay for detailed structural information. Fourteen of the fifteen peptides in the digest were seen, but this required detection of positive and negative ions and analysis in three different matrices. All six spectra showed a different peptide subset. Only one peptide could be seen in all six spectra, and five peptides were seen in only one of the six spectra.
Peak broadening during linear analysis limits the ability to resolve components with similar mass.
Broadening is caused partly by ion decomposition during flight, so that the parent and daughter ions arrive at the detector at almost, but not exactly, the same time. In reflectron analysis, an electrostatic mirror directs ions to a second detector, and during this process, parent and daughter ions are separated, providing resolution values up to about 2,000. Reflectron analysis may also provide detailed structural information about samples if they undergo post source decay, i.e., decomposition after ionization. When properly adjusted, the reflectron allows measurement of daughter ion masses. From the fragment masses, the sequences of known and unknown peptides can be determined on much simpler instrumentation than used previously.