ANALYSIS OF MACROMOLECULES USING NANOELECTROSPRAY IONIZATION MASS-SPECTROMETRY AND LOW-ENERGY COLLISION ACTIVATION

The mass spectrometric analysis of several proteins using nanoelectros pray (nanoES) with elastic collisions showed an improvement in the sen sitivity over nanoES without collisional activation. We believe this e ffect is due to a better declusterization/ionization process. Optimiza tion of the collision parameters can be easily performed during the lo ng experiment time allowed using the nanoES source. Moreover, an appar ent shift in the charge-state distribution is observed, with lower cha rged ions becoming relatively more abundant with increasing either tar get gas pressure or kinetic energy of the precursor ions. Higher charg e-state ions might be expected to have higher collision frequencies an d correspondingly lose more kinetic energy than lower charge-state ion s.