Ion transmission and ion/molecule separation using an electrostatic ion guide in chemistry ionization mass spectrometry

The performance of an electrostatic ion guide for use in chemical ionizatio n mass spectrometry is evaluated. The study focuses on the use of the ion g uide to extract charged particles in a rapidly expanding beam consisting of ions and neutral molecules. A theoretical analysis of this system is prese nted, using three-dimensional calculations of the trajectories of ions. Lab oratory measurements verifying the theoretical calculations are also report ed. The results illustrate the two principal advantages for this system: ef ficient ion transmission and ion-neutral molecule separation. A comparison between the ion guide and the commonly used electrostatic ion lenses shows that the ion guide is significantly more efficient in capturing and transpo rting charged particles from a diverging ion source. (C) 2000 Elsevier Scie nce B.V.