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Topic: ppm in XCMS centWave (Read 282 times) previous topic - next topic

  • blueskypie
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ppm in XCMS centWave
Hi,
The centWave paper says the following:
Quote
1. Mass deviation μ in ppm, typically set to a generous multiple of the mass accuracy of the mass spectrometer. We use μ = 30 ppm for the Bruker MicrOTOF-Q, which is advertised with a mass accuracy of 3-5 ppm.

But I see others use ppm=2.5, instead of 25, for Orbitrap with advertised mass accuracy < 5 ppm. Could anyone explain why?

Thanks!
  • Jan Stanstrup
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  • Administrator
Re: ppm in XCMS centWave
Reply #1 –
I would say that 2.5 is almost certainly a bad idea... It needs to be true also for the edges of peaks to work well.
I used 20 for orbitrap data and I remember that setting it significantly lower gave problems.
  • University of Copenhagen, Denmark
Blog: stanstrup.github.io
  • blueskypie
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Re: ppm in XCMS centWave
Reply #2 –
Thank you so much for the reply! And thank you for all the tutorials on your page! It's very helpful for a newcomer to this field.

Here is a slide from a tutorial by Workflow4Metabolomics. Seems for Q-TOF instruments, the ppm is set to be ~10 times of actually accuracy, but not for Orbitrap. I also see others using ppm=2.5 for Orbitrap, so I was just wondering why?
  • Last Edit: March 28, 2018, 09:49:48 AM by blueskypie