Nist standard Reference Database 1a nist 98 Mass Spectral Library with Windows Search Program (Version 7) For Use with Microsoft

The NIST Mass Spectrometry Data Center

Stephen E. Stein, Director
Evaluators:

Anzor Mikaya, Principal

Pierre Ausloos

Carol Clifton

Sharon G. Lias

Vladimir Zaikin

Damo Zhu
Programmers:

Oleg V. Fateev

Alexander A. Levitsky

Dmitrii Tchekhovskoi

W. Gary Mallard

O. David Sparkman

Joan A. Sparkman

Technology Administration

National Institute of Standards and Technology

Standard Reference Data Program

Gaithersburg, MD 20899

The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high-quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.

© 1987, 1988, 1990, 1992, 1994, 1995, 1996, 1997, 1998 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

Certain trade names and company products are mentioned in the text to specify adequately the computer products and equipment needed to use this software. In no case does such identification imply endorsement by the National Institute of Standards and Technology of these computer products and equipment, nor does it imply that the products are necessary the best available for the purpose.

Introduction

The NIST/EPA/NIH Main Library now contains spectra of more than 100,000 compounds along with associated chemical identification data including chemical structures, synonyms, and other of relevant information. The best quality spectra are placed in the Main Library; and good-quality, alternate spectra are provided in the Selected Replicates Library, bringing the total number of spectra to 129,136. Each spectrum has been carefully evaluated, and all decisions regarding selection or deletion were made only after agreement of two experienced mass spectral evaluators. While computer methods assisted in finding chemical identification errors and inconsistencies and revealed certain varieties of mass spectral errors, manual interpretation was the principal basis for this evaluation effort. All erroneous spectra from previous versions have been removed or replaced. Efforts have also been made to remove duplication of the same or edited forms of a single spectrum and to limit the replicate library to spectra showing a meaningful degree of variability. This release represents the largest increase in both quality and coverage in the 25-year history of the NIST/EPA/NIH Mass Spectral Database—the world’s most widely used reference MS database. For the first time it can be stated that the library has been fully evaluated. The objective of this effort has been to provide the best possible reference library for compound identification by mass spectral library searching.

B. Version 1.7 Search Software for Windows

This software, providing a flexible means of accessing data in the NIST and User libraries, includes:

1. 
   chemical identification by optimized, documented spectrum-matching methods,
   
2. 
   analyzing mass spectra of compounds not in the library using library data,
   
3. 
   finding spectra with pre-selected characteristics,
   
4. 
   viewing spectra by name, formula, CAS registry number, molecular weight, or ID number,
   
5. 
   User library building and maintenance, and
   
6. 
   integration with a number of commercial GC/MS data systems and spectral analysis tools.
   

While details for the operation of Version 1.7 are provided in its on-line help system, selected features are described briefly below followed by some introductory sample sessions.

When the program is first started, seven tiled windows appear on the screen (the Desktop), each with its own data and behavior. The behavior of any Window may be modified by making it active (clicking on it) and then pressing the AdjustWin button at the bottom of the Desktop. As you become familiar with program operation, you may wish to change the dimensions of some Windows or even close some of them to create a custom Desktop. When the program is restarted, it begins with the most recent Desktop. To save a window-arrangement Desktop for future use, select Desktop from the Menu Bar and then Save As… from the resulting Menu. Prior Desktops may be restored using one of the predefined names or your own name. Such arrangements describe the geometry and type of information shown in each Window, not the actual data contained in it. To restore a previous hit list, select it from the list at the top of the Hit List Window.

As with Version 1.5 and 1.6, the program offers a unique means of interpreting spectra of compounds not identified in the Library by the User spectrum search. This is most useful when no acceptable matching spectra are found in a User spectrum search of the NIST Library. At this point, by selecting Substructure Information from the Tools menu, the current hit list is analyzed, and statistical information on the composition of the unknown is derived from the hit list. For instance, the probability that any of a range of substructures is present or absent is listed (phenyl, acid, ester group, double bond, heteroatom, etc.) along with an estimate of the molecular weight and chlorine/bromine content (the latter is based only on the spectrum itself).

Starting with Version 1.6, users may import their own chemical structures with selected user spectra. This is done in the Tools/Librarian section of the program by connecting a user-drawn structure in standard MOL-file format with a user spectrum. Such structure-drawing programs are widely available (for example, ISIS/Draw may be freely downloaded from http://www.mdli.com). As before, if a user spectrum is given its CAS registry number and the Main Library has a structure for it, this structure is automatically shown with user spectra unless the user has attached an imported structure to the spectrum.

A variety of methods for automated searching and reporting of results are available. For the File menu selection, if Print automation is on, printing will follow each library search. A set of print options is also available from the “User Search Options” Window (select Search, then User spectrum). These options are of particular use when using this NIST Program with other data acquisition programs.