title: Design and performance evaluation of a novel ion funnel driven by a phase-modulated rectangular wave.
abstract: BACKGROUND
  The ion funnel has proven to be an important ion transport device. It is used in mass spectrometry as a replacement for the ion transmission limited skimmer. However, conventional out-of-phase radiofrequency (RF) supply approaches inevitably produce potential barriers, decreasing transmission efficiency. A novel RF supply method is proposed that produces better transmission performance.
  
  
  METHODS
  We designed an ion funnel driven by a phase-modulated rectangular wave (PMRW). The potential field distributions of the PMRW ion funnel and a conventional ion funnel were computer simulated to evaluate their focusing properties. A series of simulations were produced using the SIMION ion-optics simulation program to compare the transmission efficiency of the two types of funnel. Preliminary experimental results were obtained using an electrospray ionization mass spectrometry platform with polypropylene glycol, propylamine and butylamine samples.
  
  
  RESULTS
  The electrical potential distribution of a PMRW ion funnel has a bowl shape at the cross section of the electrodes, rather than in the field-free region; this benefits focusing performance. A comparison of ion trajectories and flight time data produced by the SIMION simulations showed that the potential barrier did not exist in the PMRW mode. The experimental results showed that the PMRW method increased the signal intensity by 150-200% for propylamine and butylamine and 50% for polypropylene glycol.
  
  
  CONCLUSIONS
  A novel PMRW ion funnel has been designed and developed. The simulation and experimental results indicate that the PMRW ion funnel has better transmission efficiency than the conventional ion funnel, particularly for low mass-to-charge ratio ions.
authors.affiliation: College of Instrumentation and Electrical Engineering, Jilin University, Changchun, 130012, China.
authors.forename: Hualei
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Chemistry, Fudan University, Shanghai, 200433, China.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Zhang
authors.affiliation: National Institute of Metrology, Beijing, 100013, China.
authors.forename: Yuzhuo
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Beijing Perkinje General Instrument Co., Ltd, Beijing, 100085, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Ling
authors.affiliation: College of Instrumentation and Electrical Engineering, Jilin University, Changchun, 130012, China.
authors.forename: Di
authors.initials: D
authors.lastname: Tian