ANALYSIS OF THE FRAGMENTS FROM COLLISION-INDUCED DISSOCIATION OF ELECTROSPRAY-PRODUCED PEPTIDE IONS USING A QUADRUPOLE ION-TRAP STORAGE REFLECTRON TIME-OF-FLIGHT MASS-SPECTROMETER

The capabilities of the ion trap storage/reflectron time-of-flight mass spectrometer (IT/reTOF) as a method for rapid structural analysis of low levels of peptides with relatively high resolution are demonstrated. The fragmentation generated by collision-induced dissociation (CID) of etectrospray-produced ions of peptides between the capillary exit and the skimmer of the electrospray source is analyzed by the IT/reTOF. A resolution of 2000-3000 is obtained for the fragment ions depending upon the storage time and other conditions of the particular experiment. This resolution is sufficient to resolve the isotopic distribution of the fragment ions, including the multiply charged ions, thus providing identification of the charge state. The resolution attained for fragment ions is enhanced by the use of a buffer gas and storage capabilities of the trap. It is shown that for these CID spectra such resolution can be obtained on low picomole samples on this relatively simple, inexpensive instrument.