MATRIX-ASSISTED LASER DESORPTION IONIZATION USING A NEW TANDEM QUADRUPOLE ION STORAGE TRAP, TIME-OF-FLIGHT MASS-SPECTROMETER/

A tandem quadrupole ion-storage trap, time-of-flight instrument using matrix-assisted laser desorption/ionization has been constructed, Deso rbed ions are first trapped in an RF field and collisionally relaxed p rior to time-of-night mass analysis, So far masses up to 90 kDa, a res olution of up to 700 and trapping times of up to 10 minutes have been measured with RF frequencies and amplitudes as low as 20 kHz and 40 V, respectively, The effects of pulse synchronization with the RF voltag e and of extraction voltage variation on instrument performance have b een investigated, Molecular ions of melittin have been found to underg o reactions in the gas phase during storage.