title: Effect of phase locking AC and RF voltages for high mass analysis in a quadrupole ion trap mass spectrometer.
abstract: Experiments on the influence of locking the AC and RF frequency phases on the mass resolution and line position in the mass spectra from a quadrupole ion trap mass spectrometer were carried out at low ejection values of beta z to investigate the possibility of using this effect for high mass analysis. At a typical mass scan rate of 1000 u/s the improvement for the mass resolution in these experiments did not exceed 10-20% at beta z = 0.25 compared with 200-250% at beta z = 0.5. However, without phase locking, the mass resolution at beta z = 0.25 was about two times higher than that at beta z = 0.5. Thus, the absolute values for the mass resolution observed without phase-locked AC and RF frequencies at beta z = 0.25 were about the same as at beta z = 0.5 with phase locking. This observation was explained by a significant negative contribution to the mass resolution of the ion microoscillations along the trajectory at the fundamental RF frequency which is different for the cases of beta z = 0.25 and beta z = 0.5.
authors.affiliation: Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: V M
authors.initials: VM
authors.lastname: Doroshenko
authors.forename: R J
authors.initials: RJ
authors.lastname: Cotter
mesh_terms: D002364:Caseins / Q000737:chemistry; D007834:Lasers; D013058:Mass Spectrometry / Q000295:instrumentation*; D008970:Molecular Weight; D009525:Niacin / Q000737:chemistry
chemical_list: D002364:Caseins; D009525:Niacin