Double Emission Ramp

[Bridget85]

We are running 524.2 Method with GCMS 7890/5975C Agilent
Often, having an issue with passing BFB daily check, so get the suggestion from Agilent, how help to pass BFB criteria.
After performing Autotune(sometimes BFB Autotune if BFB daily check failed) we are setting the EntLens to 0 and performing Ramp emission. Then max them and raise the Mass 69 by raising the voltage.
But always had only one ramp where all 3 mass max at one point.
Today get 2 sets of ramp.
First: Mass 69 and 502 about at Emission 14.8, then a small jump and second: all 3 mass at Emission 34.6
What it can be? I mean the first set of Mass 69 and 502.
Can we fix it?
Thanks

[chemstation]

Hi Bridget85,

Have you tried customising an S-tune to alter the voltages along the mz.

S-tune was originally implemented to de-tune the MSD, as the high mz recorded
where greater than the traditional EI spectra.

I realised on a dying MSD that I could get it to acquire the usually MSD EI spectra,
by manually entering the values I wanted the S-tune in the configuration, and then
running the S-tune, no manually tuning needed, and easier for QC acceptance
until you clean the source.

kind regards
Alex

[James_Ball]

We are running 524.2 Method with GCMS 7890/5975C Agilent
Often, having an issue with passing BFB daily check, so get the suggestion from Agilent, how help to pass BFB criteria.
After performing Autotune(sometimes BFB Autotune if BFB daily check failed) we are setting the EntLens to 0 and performing Ramp emission. Then max them and raise the Mass 69 by raising the voltage.
But always had only one ramp where all 3 mass max at one point.
Today get 2 sets of ramp.
First: Mass 69 and 502 about at Emission 14.8, then a small jump and second: all 3 mass at Emission 34.6
What it can be? I mean the first set of Mass 69 and 502.
Can we fix it?
Thanks

I normally set my emission to 29 and save then run the BFB tune. After the BFB tune I inject BFB and check the ratios. This has the Entrance Lens Offset as dynamic, which I then go into and adjust the settings in dynamic for entrance lens offset for 131 and 219 up or down and reshoot the BFB and recheck, repeating until I get a solid passing tune. Once you get accustomed to what changes provide what results on the BFB injection you can do the quickly without ever reopening the calibration gas valve, just go into manual tune, adjust by 1 volt or a fraction of volt and save and shoot, doesn't take long to hit the proper ratio.

Also if you can run the multiplier voltage at the lowest possible setting that gives you the needed sensitivity you will have less problems with linearity of the late eluting compounds.

If you have trouble with 174 being too high then increase emission 1-3, if it is too low decrease emission 1-3. Higher emission gives more lower masses and lower emission tends to give more high mass fragments.