Technical data

Overview 1
Front-end ion optics
Agilent 6200 Series TOF and 6500 Series Q-TOF LC/MS System Concepts Guide 39
Ion transport 2 (Vacuum stage 4 for 6220 TOF only)
In this fourth vacuum pumping stage, the pressure is now low
enough that there are few collisions of the ions with gas
molecules.
Ion selection (Vacuum stage 4 for Q-TOF only)
Lens 2 RF The phase of lens 2 RF is matched to that of the subsequent
quadrupole resulting in a significantly increased sensitivity.
Quad mass
filters
The quadrupoles consist of hyperbolic rods that optimize ion
transmission and spectral resolution. There tends to be more
ion loss with circular rods.
Pre-filter The end section of the quadrupole also consists of short
hyperbolic rods, but their RF voltages are only high enough to
guide ions into the collision cell.
Ion fragmentation 2 (Vacuum stage 4 for Q-TOF only)
Ions selected by the quadrupole are then passed to the collision
cell where they are fragmented.
The axial acceleration collision cell is a high pressure hexapole
assembly with its axial acceleration adjusted to maximize
sensitivity while eliminating crosstalk.
Crosstalk occurs when product ions from a previously selected
precursor appear in a product ion spectrum of a subsequently
selected precursor because of slow clearance from the collision
cell. This creates a composite product ion spectrum which can
be difficult to interpret.
The components that contribute to this higher sensitivity and
faster response are
• Small diameter hexapole collision cell
• High frequency hexapole collision cell
NOTE
The following sections are only part of the Q-TOF LC/MS instrument. The
next section in the TOF instrument is the Beam shaping (Vacuum stage 4
for both 6220 TOF and Q-TOF) on page 40.