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Neutral Loss

Description

This module performs feature annotation by matching neutral losses (=precursor m/z - fragments) against a library of annotated neutral losses (adapted from Kersten et al 2011, Kersten et al 2013, Correa&Niessen 2017 (ISBN:9781118500187)). Such neutral losses can indicate functional groups present in the molecule and help with identification. The annotation algorithm works as follows:

  • For each feature, iterate through neutral losses and compare them against a library of annotated neutral losses.
  • If the values of a neutral loss and a library neutral loss match (are inside a specified mass deviation), annotate the feature.

Parameters

  • mass_dev_ppm: the maximum allowed mass deviation difference to constitute a match
  • nonbiological: allows to specify if neutral losses characteristic to non-biological molecules (synthetic chemicals) should be included in the search. This may lead to spurious matches.

Limitations

  • Neutral loss matches can often be spurious (a neutral loss can correspond to many different molecule substructures) or can result from random noise. Therefore, they must not be trusted blindly.