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NIST Standard Reference Database 1A


NIST/EPA/NIH Mass Spectral Library with Search Program
Data Version: NIST v20
Software Version: 2.4

This database is the product of an ongoing comprehensive evaluation and expansion of the world's most widely used mass spectral reference library.

(NIST SRD 1A is available ONLY from distributors)

Contents of the NIST 20 Mass Spectral and Retention Index Libraries
Library Description Library File Name Library Contents
NIST/EPA/NIH Mass Spectral Library (EI)
Main EI MS Library mainlib Spectra for chemical compounds
Replicate EI MS Library replib >43,774 replicate spectra
Tandem (MS/MS)Library
HRAM MS/MS Library -
small molecules
hr_msms_nist> 1,026,712 spectra of 94,472 precursor ions from 27,840 chemical compounds
Low Resolution MS/MS Library -
small molecules
lr_msms_nist 215,649 spectra of 163,512 precursor ions from 28,559 chemical compounds
APCI High Resolution MS/MS Library -
small molecules
apci_msms_nist 3,555 spectra of 605 precursor ions from 246 extractable and leachable compounds
MS/MS Library -
biological peptides
biopep_msms_nist 90,244 spectra of 6,803 precursor ions from 1,904 peptides
    Total: 1,320,389 spectra of 185,608 precursor ions from 30,999 chemical compounds
GC Method / Retention Index Library
Retention Index Library


447,285 RI values for 139,963 compounds; 112,253 compounds in the Main Library have retention index data.


  • Tandem (MS/MS) Library and GC Method / Retention Index Library may be obtained as separate products.

Evaluation and Quality Control

  • Each spectrum critically examined by experienced mass spectrometrists.
  • Each chemical structure examined for correctness and consistency, using both human and computer methods.
  • Spectra of all stereoisomers intercompared.
  • Chemical names examined by experts and IUPAC names provided.
  • Thousands of spectra replaced with higher quality measurements.
  • Verified CAS registry numbers.

For more information, please visit

The scientific contact for the database is:

Stephen E. Stein
Mass Spectrometry Data Center
National Institute of Standards and Technology
Gaithersburg, MD 20899-8362
(301) 975-2505
massspec [at]

Keywords: analysis; chemical analysis; chemical databases; chemical structure; chemistry; mass spectra; mass spectrometry.

Created June 19, 2014, Updated June 12, 2020