W4M/LC-MS - Annotation

Mass spectrum
Annotation level
Database
Deconvolution
Goal

What about about mass spectrum interpretation (adduct, fragments, ionisation process) ?

At the end of the course, you will be able to :

  • Underline the differents steps towards annotation
  • Find usefull information in xcms/Camera outputs
  • Search spectrum or compound database
  • Filter results on scores
Prerequisites

Knowledge about mass spectrum interpretation (adduct, fragments, ionisation process).

Introduction
  • Preceding course section enabled you to have at your disposal a filtered list of ions and some might be the searched biomarkers of your study
  • What you may want now is to annotate/identify those compounds
  • So, what should you do to annotate/identify those compounds ?
  • This course section will show you how to exploit the variable Metadata and other available information.
Summary
  • The annotation challenge
  • From mass spectra to elemental formula
  • Using compounds databases
Contents
Conclusion
  • Annotation is still one of the main challenge in metabolomics 
  • Remember that definitive identification of compounds (level 1) can not be reached without pure standard injections
  • Once you have identified, your annotaion/identification can be used in pathway analysis tools like Metexplore !
References
  • Schymanski, E.L., P. Singer, H., Slobodnik, J., M. Ipolyi, I., Oswald, P., Krauss, M. (…) Hollender, J. (2015). Non-target screening with high-resolution mass spectrometry: critical review using a collaborative trial on water analysis.  407 : 6237. https://doi.org/10.1007/s00216-015-8681-7
  • Viant, M.R., Kurland, I.J., Jones, M.R., Dunn, W.B. (2017). How close are we to complete annotation of metabolomes ?. Chemical Biology, 37, 1-76. https://doi.org/10.1016/j.cbpa.2017.01.001