Changes in Tandem (MS/MS) NIST23 Search Program (V3.0)

• Presentation in pdf for download

Tandem MS/MS library

• 51,501 compounds, 60% more than 2020 version

• 400K precursor ions, ~2.4 million spectra

• Expanded compound classes and improved link to internet via InChIkey

• Simplified tandem library search menu

• Improved name search

• Detailed description of the new version NIST Tandem Mass Spectral Library 2023 Release

James Little: Postup rozšíření NIST Tandem Mass Spectral Library

FREE Video educational series: LC/MS Unknown Identifications Using MSMS Libraries

• Part I: Overview of Software and User-Customized Configurations
• Part II: NIST Search Software and Libraries
• Part III: More Detailed Discussion of MSMS Hybrid Search
• Part IV: Importing MSMS Spectra
• Part V: NIST Structure Searches
• Part VI: MS Interpreter Correlation of Substructure to MSMS Ions
• Part VII: Using and Creating Other MSMS Libraries
• Part VIII: Identification of Unknowns with “Spectraless” Libraries

EI library

• 40 K compounds more than 2020 version, >349 K total spectra

• Expanded compound classes and improved link to internet via InChIkey

• Measured and/or improved theoretical retention indices for all compounds

• Simplified EI library search menu

• Improved name search

• Detailed description of the new version NIST/EPA/NIH EI-MS LIBRARY 2023 Release

FREE Video educational series: Identification of unknowns in GC/MS

• Part I: Spectral Searches with NIST MS Search
• Part II: Structure Searches with NIST MS Search and Using MS Interpreter
• Part III: AMDIS (NIST) for Processing EI Mass Spectral Data Files
• Part IV: Advanced NIST Hybrid Searchof EI and MS/MS Spectra
• Part V: Creating and Sharing User EI and MS/MS Libraries

Changes in Tandem (MS/MS) NIST23 Search Program (V3.0)

• List of Changes in NIST23 Search from User Manual
• Large Increase in Tandem Spectra NIST23
• New Compound Selection Process
• Procedure of Extending the NIST Tandem Mass Spectral Library
• Simplified Menus Separating Tandem and EI Search Options

Simplified EI Library Search Options Menu: Only Tandem (MS/MS) Options!

• Only the Tandem search options shown in Identity and Similarity searches for V3.0
• Pull down menu for searches, New Partial Spectrum Search

New InChIKey Google Link to Internet in V3.0 Replaces PubChem Link in V2.4

• Much improved link to Google search when clicking on InChIKey
• Often useful to select image tab in Google results to see only images
• PubChem should still shown in the search results, but only indirectly

Databases Reference in Search Results Significantly Extended

• Many more databases referenced
• Results display shows abbreviations and the total number of references
• Search results show full name of the database
• List of databases in NIST PDF document shown on next slide
• If similar hit results for compounds with different structures, should consider the one with highest number of database references in absence of sample history

Very Much Improved Name Search in V3.0 NIST Search

• Number of characters searched increased from 16-249
• Greatly improves results for specific compound of interest
• When typing in request, spaces, commas, etc. are ignored
• Can toggle to ignore numbers if desired with a-z button, but should include when specific isomer desired
• Results at bottom of screen show tandem spectra obtained at different conditions
• Only one library searched at a time

In Summary

• Use Part O to understand changes from V3.0 to 2.4
• Then view Parts I-VIII to gain complete understanding of the software for unknown identification
• In general, all major functions and concepts are the same
• NIST just simplified the Library Search options menu
• Created an EI specific one and a Tandem (MS/MS) specific one
• Many other nice features added including improved name search, Google/InChIKey search, etc.
• See total list in manual pg 23 for other minor changes