Hi,
We have recently started experiencing issues with an established method, where the FID is not remaining lit and will intermittently restart during sequences. The system will be in the ready state and fully equilibrated before the run starts then often after the first injection we will see large disturbances in the baseline where the FID has reignited. The next few injections will often then be fine with no interference and then we will see it again for one injection. The reignition normally happens in quick succession about 3 times in the first 10 minutes of that injection. The sequence doesn't abort and the system doesn't come out of the ready/run state.
The conditions being used in the method are:
| Condition | Setting |
| Mode | Constant Flow |
| Column Flow | 1mL/min |
| Pressure | 0.584 bar |
| Split Ratio | 200:1 |
| Split Flow | 200 mL/min |
| purge flow | 3 mL/min |
| Total Flow | 204 mL/min (although the actual is reading 44 mL/min) |
| Detector Temp | 270 C |
| Air Flow | 450mL/min |
| H2 flow | 40mL/min |
| Makeup N2 | 45mL/min |
The issue started after we had to shutdown the instrument for maintenance on the Hydrogen generator which is supplying gas for 2 GCs. The generator was set to the same psi as before and is maintaining pressure with no observable issues. The GC system has been reset, along with the desktop computer. The jet has been cleaned and the column reinstalled. All gas lines have been checked for leaks and none were found, although the gas filters do appear to be saturated and log has been kept of the last change. We are changing the filters but it is not thought this is causing the issue as both GCs are being supplied by the same nitrogen line and the issue is only being observed on one of them.
Does anyone have any insights as to what else may be causing these issues?
Below is a picture of the baseline disturbances we are seeing in the online signals
