External ion accumulation of low molecular weight poly(ethylene glycol) by electrospray ionization fourier transform mass spectrometry

摘要: The combination of electrospray ionization (ESI) with Fourier transform mass spectrometry (FTMS) is a powerful tool in characterizing synthetic polymers. ESI permits the generation intact, multiply charged high ions, whereas FTMS provides resolution and correspondingly improved accuracy. However, under “nonideal” empirically determined operating conditions, discrimination effect occurs as function accumulation time that can result significant differences for calculated average values (Mn, Mw) polydispersities. A multidimensional tuning process to eliminate deleterious effects bias demonstrated several sodiated poly(ethylene glycol) samples containing oligomers masses covering 600–3350 Da regime. In addition, experiments are performed order elucidate possible mechanism(s) cause effect. It proposed extended collisions (reactive nonreactive) occur hexapole alter energy (and velocity) distributions ions before injection into trap. By choosing higher skimmer potentials, over narrower “window” preselected exhibit lower overall effects.