MS Spectrum Not Same - Xevo G2 Qtof with Xevo TQ-S Micro

[anuarhassim]

Hello there,

I'm running with both the equipment.
But getting different result m/z with same cone voltage and collision energy.

One get 391.23 and qtof get 427.0312.

Is there any solution?
Thanks.

[Gaetan Glauser]

Hi,

It would be good if you can give us a bit more information about the method (MS mode) and the analyte (e.g. molecular mass and expected pseudo-molecular ion; are 391 and 427 already fragments of the molecule?), but I can already give some hints: If I remember well the Xevo G2 has a T-wave downstream of the ion block while the TQ-S micro has a first generation Stepwave, which notoriously causes more fragmentation than the T-wave or the second generation of Stepwaves. This could explain the different spectra you observe (mass difference of 36 Da, maybe two H2O losses?).

You can try to lower the voltages on the Stepwave as much as possible (ask Waters for the specific values). If this does not work, you will have to live with it or buy a new triple quad which generates less in-source fragmentation

[carlo.annaratone]

Hi,

As said above, the TQ-S micro and the G2 have different front end ion guides. These share some commonalities but are in the end different designs. This means you'll see different in-source fragmentation patterns. However, nothing prevents you from using different cone voltages on the two instruments - they do not have the same hardware so it does not make much sense to use the same settings anyway! You'll see much closer results when fragmenting in the collision cell where the two instruments are extremely similar.