IMS FILTER rozas  2021-03-31

IMS filter rozas EDIT 2021-03-31

Hello Skyline team!

I would like to ask you something related to the drift time filter. I have made up a transition list including drift times but anyways, I should add an ion mobility library through "Transition settings-ion mobility- add" in order to filter my results taking into consideration the drift times. Is this correct?

On the other hand, I have seen that when I create an ion mobility library using drift times, the CCS is calculated automatically but, How could add the data of CCS calibration that I obtained experimentally in order to correct these values?

Thank you so much,

Kind regards

Brendan MacLean responded:  2021-03-31

Hi Laura,
Yes, I think you will want to use Ion Mobility Filtering. I am not aware of an instrument which pre-filters its spectra based on drift time. The drift time instruments I know of are those from Agilent and Waters. The Bruker timsTOF allows pre-filtering by 1/K0 in a prmPASEF method, and the SCIEX SelexION and Thermo FAIMS allow filtering by Compensation Voltage. If you think, however, that your transition list can be provided to your instrument in its method in a way that will cause it to produce filtered spectra, then in that case using IMS Filtering would be redundant and of no real benefit.

When the CCS values are present in the library, then Skyline will use those preferentially over the drift time values. You should be able to manually edit the values in the grid, but keep in mind: 1) if you edit a drift time value, you should clear the CCS that was calculated from it, or your editing will not impact the filtering, 2) if you edit a CCS value, you should probably clear the original drift time or provide a new drift time to keep from storing out-of-sync values, though in general this is less important than #1 because Skyline will use the CCS value over the drift time value.

Hope this is helpful to you. Thanks for using the IMS features and posting to the Skyline support board.


rozas responded:  2021-04-05

Thank you Brendan for your help. I will take into consideration your advices regarding the edition of CCS values.
Finally, I will use Ion Mobility Filtering because through the transition list my results were not filtered in terms of drift times.

have a nice day,