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Topic: Multiple features for narrow RT range (Read 244 times) previous topic - next topic

  • qz1234
  • [*]
Multiple features for narrow RT range
Hello there,

We have a question in regards to XCMS feature selection.

Upon preprocessing of QTOF data XCMS spits out a results table that shows multiple features across very narrow bands of RT ranges.
For example 30 different features (though often closely related ones) at a RT of 4.3 minutes. Another 15 for 4.5 minutes etc...

We've tried various preprocessing settings, but this doesn't change feature selection dramatically.

What could be going wrong?
Thanks.

  • Jan Stanstrup
  • [*][*][*][*][*]
  • Administrator
Re: Multiple features for narrow RT range
Reply #1
Are you talking about adducts and fragments? XCMS does not attempt to give you one feature per compound but one feature per ion.

CAMERA would be the standard tool to try to group ions originating from the same compound. There is however no consensus on how to statistically treat/merge those groups.
  • University of Copenhagen, Denmark
Blog: stanstrup.github.io

  • qz1234
  • [*]
Re: Multiple features for narrow RT range
Reply #2
Excellent. That actually explains the EIC and TIC chromatograms versus the feature selection.
Thanks  ;D