Analytical Chemistry Information at NIST

Stephen R. Heller

USDA, ARS, Beltsville, MD 20705

The US National Institute of Standards and Technology (NIST) has recently made available a good deal of chemical data on its web site. Much of this is in the area of analytical chemistry, with even more to be coming in the near future. The center of the NIST data activity is their Office of Standard Reference Data (SRD). For over thirty years, the Standard Reference Data Program has provided well-documented numeric data to scientists and engineers for use in technical problem-solving, research, and development. These recommended values are based on data which have been extracted from the world's literature, assessed for reliability, and then evaluated to select the preferred values.

The following is the home page of NIST/SRD:

NIST Standard Reference Data Products Catalog

National Institute of Standards and Technology


Standard Reference Data Products CATALOG

DATA. Reliable, evaluated, numeric data.

For critical technical decisions, engineers and scientists count on the Standard Reference Data (SRD®) Program at NIST.

NIST Online Reference Databases
New and Updated Databases.
Database descriptions are accessed through:
   List of all databases by scientific discipline.
   List of all databases with prices.
Other NIST Databases - Optical character recognition data sets . . .
Journal of Physical and Chemical Reference Data.

The National Institute of Standards and Technology (NIST) was formerly the National Bureau of Standards (NBS).

Suggestions and comments:

Standard Reference Data Products CATALOG

The NIST Standard Reference Database Series consists of over 50 electronic databases. The majority of databases are versatile, sophisticated PC packages which have gained wide acceptance and approval. SRD® provides clear, concise documentation with each PC package.

NIST Standard Reference Database Series
Analytical Chemistry
Atomic and Molecular Physics

Chemical and Crystal Structure
Chemical Kinetics
Industrial Fluids and Chemical Engineering

Materials Properties
Surface Data
Thermodynamics and Thermochemistry

Other NIST Databases
Optical character recognition data sets (fingerprints, handwriting...)
International Database of Reference Materials

Most databases are updated yearly, with the addition of more data and more software capabilities. Comments and suggestions are continually solicited from users in order to improve software features and identify new areas of research.

Please browse our latest (Vol. 1, No. 2) newsletter, SRD DATA LINK, for up-to-date information.

Additionally, the NIST/EPA/NIH Mass Spectral Library is incorporated into commercial mass spectrometers which are in service worldwide. SRD is proud to announce the new Microsoft Windows(tm) version of the Mass Spectral Database.

NIST DATA Homepage

NIST Technology 
Services NI ST Virtual Library

Last Update 21_October_1996

The analytical databases and publications referred to above are a comprehensive set of easy-to-use databases that help the analytical chemist identify unknown materials, and in many cases, once identified, avoid the need to recharacterize a substance.

The data have been fully evaluated using a variety of techniques. When appropriate, duplicate measurements have been included for completeness. The databases are updated and expanded on a regular basis. These PC databases have sophisticated software that enable searches that take only seconds.

Mass Spectra
NIST/EPA/NIH Mass Spectral
NIST/EPA/NIH Mass Spectral DOS Version
NIST/EPA/NIH Mass Spectral Windows Version
NIST/EPA Gas-Phase Infrared
NIST X-Ray Photoelectron Spectroscopy
NIST Surface Structure
Diffraction Data
NIST/Sandia/ICDD Electron Diffraction
NIST Crystal Data
Spectrum Analysis
NIST/NIH Desktop Spectrum Analyzer Program and X-Ray Database
Publications in Analytical Chemistry

Another one of the links from this home page is to a list of NIST online databases. These include:

First, there is the Physical Reference Data of the NIST Physics Laboratory. There are several online databases listed on this home page in the areas of physical constants, atomic and molecular spectroscopic data, and x-ray and gamma-ray data.

Second, there is the Electron Interactions with Plasma Processing Gases data excerpted from an article to be published in the Journal of Physical and Chemical Reference Data (JPCRD). Presented here are collision cross section data and electron transport coefficients for gases used in the manufacturing of semiconductor devices. Third, and last, there is the first edition of The NIST WebBook is the NIST Chemistry WebBook which contains thermodynamic data for over 5000 compounds and ion-energetics data for over 10000 compounds. The user may search on specific compounds based on name, chemical formula or CAS registry number. Structures are given for all species, as well as common and commercial names.

It is this last item, the Chemistry Webbook, the home page of which is shown below, is what I want to describe and demonstrate here.

NIST Chemistry WebBook

NIST Standard Reference Database Number 69

© 1991, 1994, 1996 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

NIST reserves the right to charge for these data in the future.

Please choose one of the following search options:

Note: The pages in this site are best viewed with a browser that supports tables.

This site provides thermodynamic and ion energetics data complied by NIST under the Standard Reference Data Program.

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 judgement. 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.

NIST ONLINE Reference Databases

NIST WWW Home Page

If you have comments or questions about this site, please contact

The example chosen from this database of ion potential and thermochemsitry data is for pyridine. A name search and a formula search was chosen, and not a CAS Registry number search, for no particular reason, other than to show what two typical searches look like. As one can see, the seacrhes work essentially the same way. The first figure below shows the choices of seacrhes on the Chemsitry Webbook home page, the second page and thrid pages show the formula and name searches, and finally the last page shows the results and all the data about pyridine. Chemical Formula Search

Search for Species Data by Chemical Formula

Rules for chemical formulas:

Please enter the desired chemical formula:

Please select the desired units for thermodynamic data: SI Calories

Press here to search:

NIST Chemistry WebBook

If you have comments or questions about this site, please contact

Chemical Name Search

Search for Species Data by Chemical Name

Notice:The database currently used for name searches contains only a subset of commonly used names. If a name search fails, you may be able to find the desired coupound through a formula search.

Please enter a chemical species name (e.g., methane):

Please select the desired units for themodynamic data: SI Calories

Press here to search:

NIST Chemistry WebBook

If you have comments or questions about this site, please contact



Thermochemical Data:

Quantity Value Units Source
Df,298K,gas 140 ± 0.8 kJ/mol 79KUD/KUD3
298K,gas 282.6 J/(mol K) 69STU/WES

Heat Capacity (C°p) Data:

Temperature (K) 300.0
p (J/(mol K)) 78.20

Ionization Potential Data:

Value from NIST Critical Review (88LIA/BAR):  9.25 eV

Value (eV) Method Source
9.34 ± 0.03 EI 84ARI/YOS
9.25 TIMS 82LIF
9.60 PE 81KIM/KAT
9.26 PE 78UTS/KOB
9.25 PI 78ELA/BER
9.74 ± 0.05 EI 76ZAR/ORE
~9.5 EI 75VAN/PLA
9.85 ± 0.1 EI 74STE/GRU
9.263 PE 72KIN/MUR
9.66 ± 0.03 EI 72JOH/MEL
9.70 EI 71DIS/FOF2
9.70 ± 0.05 EI 71DIS/FOF
9.4 PI 61TER
9.51(V) PE 78KLA/NOV
9.66(V) PE 74KOB/NAG2
9.7(V) PE 73BAT/HEI
9.60 ± 0.5 (V) PE 72HEI/HOR
9.59(V) PE 70GLE/HEI

Explanation of terms and codes

Appearance Potential Data:

Ion Value (eV) Other Products Method Source
C4H4 11.84 ± 0.05 HCN TIMS 84LIF/MAL
C4H4 12.55 ± 0.1 HCN EI 84BUR/HOL3
C4H4 12.34 ± 0.05 HCN EI 84BUR/HOL3
C4H4 11.95 ± 0.2 HCN TIMS 82LIF
C4H4 11.8 HCN N/A 78ELA/BER
C4H4 12.34 ± 0.1 HCN EI 77ROS/MCC
C4H4 13.41 ± 0.05 HCN EI 76ZAR/ORE

Explanation of terms and codes

Literature References:

Kudchadker, A.P.;Kudchadker, S.A., Pyridine and Phenylpyridines, API Monograph 710-79,American Petroleum Institute,Washington,DC, 1979, 1.

Stull, D.R.;Westrum,Jr., E.F.;Sinke, G.C., The Chemical Thermodynamics of Organic Compounds, John Wiley,New York, 1969, 1.

Lias,S.G.; Bartmess,J.E.; Liebman,J.F.; Holmes,J.L.; Levin,R.D.; Mallard,W.G., Gas-Phase Ion and Neutral Thermochemistry, J. Phys. Chem. Ref. Data., 1988, 17, Suppl. 1.

Arimura,M.; Yoshikawa,Y., Ionization efficiency and ionization energy of cyclic compounds by electron impact, Mass Spectrosc. (Tokyo), 1984, 32, 375.

Lifshitz,C., Time-dependent mass spectra and breakdown graphs. 2. The kinetic shift in pyridine, J. Phys. Chem., 1982, 86, 606.

Kimura,K.; Katsumata,S.; Achiba,Y. Yamazaki,T.; Iwata,S., Ionization energies, Ab initio assignments, and valence electronic structure for 200 molecules, Handbook of HeI Photoelectron Spectra of Fundamental Organic Compounds, Japan Scientific Soc. Press, Tokyo, 1981.

Utsunomiya,C.; Kobayashi,T.; Nagakura,S., Photoelectron angular distribution measurements for some pyridines, Bull. Chem. Soc. Jpn., 1978, 451, 3482.

Eland,J.H.D.; Berkowitz,J.; Schulte,H.; Frey,R., Rates of unimolecular pyridine ion decay and the heat of formation of C4H4+, Int. J. Mass Spectrom. Ion Phys., 1978, 28, 297.

Zaretskii,Z.V.I.: Oren,D.; Kelner,L., Automatic method for the measurement of the electron impact ionization and appearance potentials, Appl. Spectrosc., 1976, 30, 366.

Van Veen,E.H.; Plantenga,F.L., Threshold electron-impact excitation spectrum of pyridine, Chem. Phys. Lett., 1975, 30, 28.

Stefanovic,D.; Grutzmacher,H.F., The ionisation potential of some substituted pyridines, Org. Mass Spectrom., 1974, 9, 1052.

King,G.H.; Murrell,J.N.; Suffolk,R.J., The vacuum-ultraviolet photoelectron spectra of fluoropyridines, J. Chem. Soc. Dalton Trans., 1972, 564.

Johnstone,R.A.W.; Mellon,F.A., Electron-impact ionization and appearance potentials, J. Chem. Soc. Faraday Trans. 2, 1972, 68, 1209.

Distefano,G.; Foffani,A.; Innorta,G.; Pignataro,S., Electron impact ionization potentials of some manganese, chromium and tungsten organometallic derivatives, Int. J. Mass Spectrom. Ion Phys., 1971, 7, 383.

Distefano,G.; Foffani,A.; Innorta,G.; Pignataro,S., Mass spectrometric study of transition metal complexes with ligands having nitrogen or sulphur as donor atom, Advan. Mass Spectrom., 1971, 5, 696.

Terenin,A., Charge transfer in organic solids, induced by light, Proc. Chem. Soc., 1961, 321.

Klasinc,L.; Novak,I.; Scholz,M.; Kluge,G., Photoelektronenspektren substituierter Pyridine und Benzole und ihre Interpretation durch die CNDO/SWW-Methode, Croat. Chem. Acta, 1978, 51, 43.

Kobayashi,T.; Nagakura,S., Photoelectron spectra of aminopyridines and cyanopyridines, J. Electron Spectrosc. Relat. Phenom., 1974, 4, 207.

Batich,C.; Heilbronner,E.; Hornung,V.; Ashe,A.J.; Clark,D.T.; Cobley,U.T.; Kilcast,D.; Scanlan,I., Photoelectron spectra of phosphabenzen, arsabenzene, and stibabenzene, J. Am. Chem. Soc., 1973, 95, 928.

Heilbronner,E.; Hornung,V.; Pinkerton,F.H.; Thames,S.F., 31. Photoelectron spectra of azabenzenes and azanaphthalenes: III. The orbital sequence in methyl- and trimethylsilyl- substituted pyridines, Helv. Chim. Acta, 1972, 55, 289.

Gleiter,R.; Heilbronner,E.; Hornung,V., Lone pair interaction in pyridazine, pyrimidine, and pyrazine, Angew. Chem. Int. Ed., 1970, 9, 901.

Lifshitz,C.; Malinovich,Y., Time resolved photoionization mass spectrometry in the millisecond range, Int. J. Mass Spec. Ion Proc., 1984, 60, 99.

Burgers,P.C.; Holmes,J.L., Fragmentation rate constants and appearance energies for reactions having a large kinetic shift and the energy partitioning in their metastable decomposition, Int. J. Mass Spectrom. Ion Proc., 1984, 58, 15.

Rosenstock,H.M.; McCulloh,K.E.; Lossing,F.P., On the mechanisms of C6H6 ionization fragmentation, Int. J. Mass Spectrom. Ion Phys., 1977, 25, 327.


NIST Chemistry WebBook

If you have comments or questions about this site, please contact


NIST is a unique and valuable source of scientific data. It is now just starting to make some of this data available, presently at no cost, to the chemical community. Plans are now underway to expand the types and amounts of data which will be on the Chemistry Webbook site. Included in this will be limited, but useful, access to the NIST IR and mass spectral data. As the amount of high quality data available increases, this web site will be an even more valuable tool. I suggest you visit it often.

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