I haven't had your specific problem but there are some hardware related
issues that can affect peak shape that you may want to consider. Make sure
the slit is not misshapen. The new ones have a straight and narrow opening.
Our old ones tend to widen and round out at the ends. The source magnets
affect linearity and possibly the peak shape too. If you have ever dropped
one the electron cloud in the ion source can be affected because the
magnetic field can change when jarred suddenly.

Good luck,

On Wed, Dec 16, 2015 at 9:05 AM, Andrew Cooper <[log in to unmask]>

> Hello Isogeochem family,
> I have encountered difficulty with our ThermoFisher Delta Plus Mass Spec,
> involving really ugly peak shapes.  This MS has always been finicky, but it
> recently moved into unusable for analysis.
> We cleaned the source recently and it should have resulted in a nice and
> clean beam and peak shape, however poor peak shape persisted, specifically
> for CO2 analysis, the 44 and 45 never quite overlap.  Anyone have any past
> problems and solutions for peak shape improvements on a Delta Plus.
> We are trying numerous different focus settings to see if we are wildly
> off-kilter somewhere.  Any ideas are welcome.  Board Swaps? Electrical
> proofs to detect board or faraday cup problems?
> Thanks for the help as we try to salvage an older MS,
> Andrew Cooper
> Isotope Ratio Chemist

Brad Erkkila
YASIC Manager
Yale Institute for Biospheric Studies
21 Sachem Street
New Haven, CT 06511