LC/MS Unknown Identifications Using MSMS Libraries Part VII: Using and Creating Other MSMS Libraries | LabRulez LCMS

LC/MS Unknown Identifications Using MSMS Libraries Part VII: Using and Creating Other MSMS Libraries

Th, 27.5.2021
| Original article from: Mass Spec Interpretation Services/James Little
A series of videos exploring the use of NIST Search Software for the identification of unknowns using tandem (MS/MS) spectra.
Video placeholder

Mass Spec Interpretation Services/James Little: Using and Creating Other MSMS Libraries

MS/MS (Tandem) spectra can be used to identify unknowns employing library searches. This is accomplished in much the same approach as that employed for EI GC-MS with the NIST search software. The much improved NIST Search Version 2.4 is included with the 2020 library release.

I will attempt to introduce the user to the use of the NIST Version 2.4 search software employing NIST, Wiley, “crowd-sourced (MoNA)”, and user libraries for the identification of unknowns.

NIST has an ambitious program to extend their already comprehensive, high-quality MS/MS databases.

See the following link: NIST Pipeline for Extending MS/MS Libraries

This involves a very comprehensive process for selecting pertinent compounds for purchase and subsequent analyses. The problem with variability of the spectra is reduced by analyzing the samples on a variety of instruments at a variety of energy levels (20 steps). In addition, many different precursor ions and fragment ions are characterized (MSⁿ). This has already led to a very large high quality library of accurate mass MS/MS spectra in the 2020 release version (31K compounds/1.3 M spectra) and the effort is ongoing.

The Part VII will cover:

Detailed Handouts including tables of content are available in the LabRulezLCMS library.

  • Introduction to Presenter, James Little
  • Table of Contents
  • Series of Talks: LCMS Unknown Identifications Using MSMS Libraries
  • Read This Before Utilizing Handout
  • Philosophy on Incorporating User and Commercial Libraries in Identifications
  • User Libraries Converted and Approach
  • NIST Lib2NIST Utility for Library Conversions
  • Accessing Lib2NIST Utility
  • Quality of MoNA and Converting to NIST format
  • Low Resolution (lr_) versus High Resolution MSMS NIST Libraries
  • Problems Converting and Searching User Libraries and “Work-Arounds”
  • Composition of the MoNA Libraries and Structures in MoNA GCMS Library
  • Conversion of Wiley Commercial Libraries with Lib2NIST
  • Conversion of Personal User Library with no Precursor_m/z field
  • PowerShell Script for Adding Precursor_m/z to Personal User Library
  • Creating/Adding User Library within NIST Search Program
  • What If My Imported Library Spectrum Contained No Precursor_m/z Field?
  • What IF I Need to Add Several Different Fields for a Set of Spectra?
  • “Re(Index)” Library Indices After Additions or Creating New Library
  • Automatic Distribution of Eastman Libraries Over Network
  • Live Demo on YouTubeWebinar References (Internet Links)
  • Acknowledgements

Future parts will focus on:

  • Part VIII: Identification of Unknowns with “Spectraless” Libraries

The past sections have focused on:

James Little/Mass Spec Interpretation Services
Other projects
Follow us
More information
WebinarsAbout usContact usTerms of use

LabRulez s.r.o., all rights reserved.