Technical data

38 Agilent 6200 Series TOF and 6500 Series Q-TOF LC/MS System Concepts Guide

1Overview

Front-end ion optics

For information on the various ion sources, see “How do

different ion sources work?” on page 16

After the API source forms ions, the

Agilent 6200 Series TOF or

6500 Series Q-TOF LC/MS system

performs the following

operations, organized according to the stages of the ion path

and the vacuum stages of the

TOF or Q-TOF. See Figure 8 on

page 28 for details.

Ion enrichment (Vacuum stage 1)

Ions produced in an API source are electrostatically drawn

through a drying gas and then pneumatically conducted

through a heated sampling capillary into the first stage of the

vacuum system. The majority of drying gas and solvent vapor

are deflected by the skimmer and exhausted by a rough pump.

The ions that pass through the skimmer pass into the second

stage of the vacuum system.

Ion transport 1 (Vacuum stage 2 and vacuum stage 3)

An octopole ion guide is a set of

small parallel metal rods with a

common open axis through which

the ions can pass.

In this stage the ions are immediately focused by an octopole

ion guide. Radio frequency voltage applied to the parallel

octopole rods repel ions above a particular mass range toward

the center of the rod set. The ions pass through the octopole ion

guide because of the momentum obtained from being drawn

from atmospheric pressure through the sampling capillary.

In a Q-TOF and in the Agilent G6224 and G6230 TOF, the

octopole spans both the 2nd and the 3rd vacuum stages. Ions

exit the octopole and pass through two focussing lenses and an

RF lens.

In an Agilent 6220 TOF, the ions exit the first ion guide and pass

into the third stage of the vacuum system. In the third stage of

the vacuum, the ions are passed onto a second octopole

assembly (octopole 2) which then sends the ion on to the beam

shaping assembly.