The ion concentrating routing multipole (ICRM) is an active collision cell, which can also trap ions. The assembly includes a split gate lens, an L2 lens, quadrupole rods, and L31 and L32 lenses.
| No. | Description | No. | Description |
|---|---|---|---|
1 | L31 lens and L32 lens | 2 | Split gate lens and L2 lens |
Two PCB halves are connected together to form a sealed gas chamber that encloses the RF-only quadrupole ion guide, which is where the higher-energy collision dissociation (HCD) of ions can take place if nitrogen gas is present. The collision cell has an axial field down its length to increase throughput speed.
The split gate lens starts and stops the injection of ions into the ICRM by deflecting the beam at the appropriate times. The offset voltage on all the split gate lenses depends on the calibration of the system, but the differential voltages used to deflect the beam are approximately ±100 V.
The L2 lens is located behind the split gate and serves several functions. It focuses the ions into the ICRM, acts as a barrier to minimize the amount of collision gas that enters the quadrupole mass analyzer from the ICRM, and shields the quadrupole mass analyzer from the RF voltage applied to the ICRM (or vice versa). A circular hole in the center of the lens allow the ion beam to pass through.
The quadrupole rods are bent into a 90-degree arc, which reduces the footprint of the instrument, prevents the transmission of unwanted neutral species to the detector, and dramatically lowers the noise level in the scan data.
The L31 lens acts as a barrier to minimize the amount of collision gas that enters MP3 from the ICRM. Together, the L31 and L32 lenses form a two-element aperture lens to focus the ions into MP3. Circular holes in the center of the lenses allow the ion beam to pass through.