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- Posts: 15
- Joined: Wed Sep 13, 2017 1:14 pm
after solving the noise issue on our Agilent MS7000a system, we still have problems with the peak shape. We noticed deteriorating peak shapes for quite some time with a rather wide range of analytes (also before the noise issue came up).
This example of an alkane standard mix was measured without time filtering. When I activate time filtering (I think it's on by default), the peak shape is almost perfectly Gaussian. I find this worrying since we may have been experiencing this issue for quite some time, but nobody may have noticed since time filtering was on all the time.
Agilent have suggested that the Quad 1 may need to be cleaned, as the abundances of the higher m/z in the tune are way lower in the Q1 compared to Q2. I would not rule that out but our samples are usually really clean and do not contain much dirt. From my understanding the quartz/gold quads should not require cleaning.
The most recent tune report can be found here.
Another diagnostic would be that the filament current fluctuates between 34.9 and 35.2 µA. Agilent say that fluctuations of +/- 1 µA may cause zig-zag peaks, but this should not be an issue in our case.
The ion source is clean and switching between the brand new filaments does not change anything with regards to the peak shape.
Any tips regarding trouble shooting are highly appreciated.
Thanks,
cb23