HP5972 autotune 502 peak abundance

[Wendy]

Hello,

I have a problem with m/z 502 abundance when running standard autotune using PFTBA with HP 5972 ms recently. About two weeks ago when I switched from filament 2 to filament 1, 502/69 jumped from normal 2~4% to 16%. Then I switched it back to filament 2, the abundence seemed normal. After several days' running, I tried filament 1, the 502 abundence seemed normal again.

Today the mass 502/69 jumped to more than 15% after I replaced the Helium tank (it was 2% ~ 4%). I have tuned it several times using both filament 1 and 2, and the abundance is still above 15%.

Any suggestion will be appreciated.

[Rick]

Hi!
Give me more information about your tune result:
Do you use Standard tune or Autotune?
Number of peak on your tune report?
Reppeler voltage?
Foreline?
ect....

[Consumer Products Guy]

Did you accidentally choose the option for high mass auto-tune to get more sensitivity at the higher masses??

[Wendy]

Thank you, Rick and Consumer Products Guy!
I used Standard Spectra Autotune. The Set Normial %502 was 3. The tune parameters on Monday was:

EMVolts: 2118 / AmuGain: 277
Xray: 55.6 / AmuOffs: 63
Emission: 35.0 / Wid219 : -0.066
Ms Temp: 186 / TTI : OFF
Vacuum: 47 / DC Pol: POS



Mass / Abund / Rel Abund / Iso Mass / Iso Abund / Iso Ratio
69.00 / 278464 / 100 / 70.00 / 2329 / 0.84
219.00/ 106688 / 38.31 / 220.10 / 4793 / 4.49
502.00 / 41288 / 14.83 / 503.10 / 4173 / 10.11

I re-tuned it this morning and I got

EMVolts: 1976 / AmuGain 280
Xray 51.3 / AmuOffs 74
Emission 35.0 / Wid219 0.011
Ms Temp 184 / TTI OFF
Vacuum 48 / DC Pol POS


Mass / Abund / Rel Abund / Iso Mass / Iso Abund / Iso Ratio
69.00 / 299328 / 100 / 70.00 / 3636 / 1.21
219.00/ 135552/ 45.29 / 220.10 / 5605 / 4.13
502.00 / 8926 / 2.98 / 503.10 / 904 / 10.13

This instrument just sat there for nearly two days and the tune parameters changed so much. This has happened recently. Is there anything wrong besides the ion source box needs to be cleaned? Thank you for your time.

[Rick]

Filament is not your problem and i don't think that your source is your problem....isolate your problem

Try this:
1-Cap your interface inlet....you will able to isolate your ms system only (no helium)
Tune and check....

2-Check if your calibration vial is full or empty

3-Clean your source

4-Rotate of 1/2 turn your Electron multiplier



Your MS temp is 184 today, but yesterday, your ms is at 186...why??and what is your reppeler voltage?

[Consumer Products Guy]

Rick: 5972s (and 5971s) heat the MS by indirect heating of the transfer line temperature, so a difference of 2 degrees is not significant.