The Fragmentor parameter controls the voltage applied to the exit of the capillary. The Fragmentor voltage affects the transmission and fragmentation of sample ions.
In general, the higher the fragmentor voltage, the more fragmentation will occur. With the 6120C LC/MS, higher Fragmentor voltages often result in better ion transmission in compounds that do not fragment readily. The Fragmentor voltage gives the ions a "push" that helps them traverse the relatively high pressure region between the exit of the capillary and skimmer 1.
For the 6125C, 6130C, and 6135C, the ion optics have been designed to reduce the ion focusing effect of the Fragmentor. This design has resulted in a significantly lower increase in ion transmission with increasing Fragmentor voltage for compounds that do not fragment readily.
Optimum Fragmentor voltage is compound dependent. Therefore, the Fragmentor voltages used during tuning are not used for data acquisition. The Fragmentor voltages used for data acquisition are specified in the method. For analysis of unknowns, the Fragmentor should be set to a low, constant value to avoid fragmentation. Typical values for analysis of unknowns:
6120C LC/MS 70 V
6125C, 6130C, and 6135C LC/MS 100 V
During manual tuning, the Fragmentor voltage can be ramped to find an optimum value to use in Tune.
You set the Fragmentor voltage in the Scan Segments table. See Method > Acquisition (LC/MS).
Ramp defaults and limits for the 6120C are:
| Default (volts) | Limits (volts) | |
|---|---|---|
| Start (From) | 0 | 0 to (Stop - Step) |
| Stop (to) | 250 | (Start + Step) to 380 |
| Step Size (by) | 3 | 1 to (Stop - Start) |
Ramp defaults and limits for the 6130C are:
| Default (volts) | Limits (volts) | |
|---|---|---|
| Start (From) | 50 | 0 to (Stop - Step) |
| Stop (to) | 380 | (Start + Step) to 380 |
| Step Size (by) | 4 | 1 to (Stop - Start) |
Dynamic Ramp
The Fragmentor voltage can also be dynamically ramped (see Tune Fragmentor Section (LC/MS)). Dynamic ramping is used during manual tuning. It is also especially useful for target compound and signature mass analyses.
Other
In the 6120C LC/MS, the Fragmentor voltage and the voltage applied to skimmer 1 are linked.
See Also