Two important software innovations have been made to the NIST/EPA/NIH Mass Spectral Database, a major international resource for analytical chemists and environmental scientists to use in identifying unknown substances. The database is available from the National Institute of Standards and Technology for scientific instruments and for personal computers.
The software innovations include a new "Dynamic Link Library" system that offers distributors of the database a prepackaged program that can be directly incorporated in mass spectrometers without any reformatting or indexing. The PC version has been updated with new features that provide a more efficient way of searching the database to reduce the chance that a correct match will be missed.
The library of 74,000 electron mass spectra of 62,235 chemical compounds is one of the most widely known standard reference data products from NIST. Users include scientists in the chemical, pharmaceutical, food and beverage, rubber, petroleum, aerospace, telecommunications and computer industries as well as hospitals, environmental laboratories and law enforcement agencies.
Mass spectrometry is the most extensively used instrument technique in analytical chemistry. It involves the ionizing of molecules of an unknown sample. These ionized molecules undergo dissociation (breaking up into simpler parts) and the ionized fragments then are analyzed according to their mass. This generates a "spectrum," which--like a fingerprint--is characteristic of the chemical species.
The mass spectral database is distributed by the makers of mass spectrometers as an integral part of instrument data systems. In the past, manufacturers had to reformat and index the data files from NIST, then write and maintain their own software for the data collection. Software developed for the PC version also is provided for seamless integration in commercial instruments for the first time.
The PC version has a new "incremental" name search that provides a display of dictionary-sorted names that track the selection entered by the user. This makes it easy to observe other similar compound names in the system. The program allows the user to search for a particular spectrum by name, chemical formula or Chemical Abstracts Registry Number; or to search for a spectrum that matches the spectrum of an unknown chemical compound. The PC version also has a file of 12,000 replicate spectra that were previously available only in commercial instruments.
Stephen E. Stein, manager of the NIST Mass Spectral Data Center, explains that a replicate spectrum is a second or third spectrum of the same compound, often taken under different instrument conditions. Each spectrum is usually similar to others in its group, but not identical. Statistical analysis suggests that a user is more likely to retrieve the correct spectrum out of a database when replicates are included, said Stein.
For information on the 1994 NIST/EPA/NIH Mass Spectral Database, Standard Reference Database 1, or for 1A, Version 4.5 for PCs, contact the Standard Reference Data Program, A320 Physics Building, NIST, Gaithersburg, Md. 20899-0001, (301) 975-2208, fax: (301) 926-0416, e-mail: SRDATA [at] enh.nist.gov (via Internet).
The PC version is available on 3«-inch high-density disks for $1,290 (5-inch disks available only by special request). It requires MS DOS 2.1 or later, 640K memory and a color monitor. There also is a CD-ROM version available for $1,200. It requires 520K memory and a Hewlett-Packard LaserJet or Epson compatible printer. Upgrades from all previous PC editions are $200.
As a non-regulatory agency of the Commerce Department's Technology Administration, NIST promotes U.S. economic growth by working with industry to develop and apply technology, measurements and standards.