Which MS1 trace is imported in thermo data?

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Which MS1 trace is imported in thermo data? michelle dubuke17846  2019-05-31
 

Hi,

I'm importing data that was acquired using lockmass correction on a QE-HFX, and in Xcalibur there are two profile traces - lockmass corrected, and non corrected. Which of these does Skyline import when it generats the XIC for the data?

Thanks!
Michelle

 
 
matt.chambers42 responded:  2019-05-31

Hi MIchelle, are you saying that the file has 2 copies of every scan, one lockmass-corrected and one not?

 
michelle dubuke17846 responded:  2019-05-31

Hi Matt,

In Xcalibur, yes; there is a different trace for lockmass corrected, non-corrected, as well as a trace if there are any polarity switching events.

--Michelle

 
matt.chambers42 responded:  2019-05-31

For the moment, ignore the chromatogram traces in Xcalibur please. What are the actual spectra? Some are lock-mass corrected and some are not? Is it like every scan is collected once uncorrected and then stored again as corrected? If so, do the scans have 2 different retention times?

We'll probably need to see the data file (can you upload it?), but if the scans have different RTs, then I suspect Skyline will be using both uncorrected and corrected scans. There's nothing in ProteoWizard or Skyline to check for this case. And it seems quite an odd one. If each scan is duplicated, your files will be twice as large but without any real benefit (unless of course you are trying to evaluate the benefit you get from lock mass correction) :)

 
michelle dubuke17846 responded:  2019-05-31

HI Matt,

Unfortunately I can't upload the file (proprietary info), but it turns out that this particular file doesn't have the separate spectra; I was confusing it with an older instrument's data acquisition. So, thanks for the help!

--Michelle