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- Posts: 1
- Joined: Wed Jul 31, 2024 5:17 pm
- Location: United States
Hello!
We have an agilent 5977A MSD with a 7890B GC operating in PCI. We are having issues with autotune, specifically the MSD is needing to ramp the methane gas flow from the suggested 20 to around 38 to achieve an ion ratio (m/z 28/27) of the suggested 2.2. There are currently no error messages, but when running a QAQC after autotune we are getting low sensitivity/response.
Things we have tried so far:
1) New methane tank.
2) Venting, cleaning the CI source and pumping down
3) Checked for leaks/changed the regulator for the tank
4) Checked for leaks- no peak for water (m/z 19) or air (m/z 32) in the tune file
5) Tune in EI seems fine
6) Checked the PFDTD calibrant level
7) We believe the methane is reaching the source as the vacuum is 2E-4 T which, checking the pressure measurement table, corresponds to 35% which is what our MFC is ramping up to to reach the correct ion ratio
A new tune file, just incase the current is corrupt
9) Tried the 'setting up methane flow', still has the same MFC ramping issue.
We get no other obvious errors, other than the ramping it seems to "pass" autotune, but we still get low sensitivity when doing QAQC. Any suggestions would be greatly appreciated thanks!
We have an agilent 5977A MSD with a 7890B GC operating in PCI. We are having issues with autotune, specifically the MSD is needing to ramp the methane gas flow from the suggested 20 to around 38 to achieve an ion ratio (m/z 28/27) of the suggested 2.2. There are currently no error messages, but when running a QAQC after autotune we are getting low sensitivity/response.
Things we have tried so far:
1) New methane tank.
2) Venting, cleaning the CI source and pumping down
3) Checked for leaks/changed the regulator for the tank
4) Checked for leaks- no peak for water (m/z 19) or air (m/z 32) in the tune file
5) Tune in EI seems fine
6) Checked the PFDTD calibrant level
7) We believe the methane is reaching the source as the vacuum is 2E-4 T which, checking the pressure measurement table, corresponds to 35% which is what our MFC is ramping up to to reach the correct ion ratio
A new tune file, just incase the current is corrupt9) Tried the 'setting up methane flow', still has the same MFC ramping issue.
We get no other obvious errors, other than the ramping it seems to "pass" autotune, but we still get low sensitivity when doing QAQC. Any suggestions would be greatly appreciated thanks!
