Each list contains 5–20 citations to articles that make mention of one of the two NIST Mass Spectral Libraries (NIST/EPA/NIH Library of EI Spectra or the NIST Tandem Library of Product‑ion Mass Spectra). During this period, I have received list of citations for both of these strings every two to five days. Because of my involvement with NIST, I have subscribed to two search strings in Google Scholar Alerts since 5 October 2014 ( and " ]). The point is that it is not only necessary to be specific about the publisher of the library but also the edition of the mass spectral library as well as the search program used. Or, the different first Hits could be due to complex search algorithm differences in the case of the NIST MS Search program vs the PBM search of ChemStation.
Spectra for approximately ~60 K new compounds were added between these two releases. In the example of a difference between the search of the NIST 14 and NIST 20 EI libraries using the same search program, it can be as simple as the addition of the spectrum of the unidentified compound to the library between editions. There is not one root cause for these differences. Even when the same mass spectrum is searched against two different versions of the NIST/EPA/NIH EI Mass Spectral Library (NIST 14 and NIST 20) using the same search program (NIST 20’s MS Search v.2.4) two different compounds can be found as the first Hit. Two different compounds can be found as the first Hit when the NIST/EPA/NIH EI Mass Spectral Library (NIST 20) is searched using the NIST MS Search Program v.2.4 or the Probability Based Matching (PBM) search program, which is a part of the Agilent Technologies (Santa Clara, CA, USA) ChemStation Data Analysis program.
Two different compounds can be found as the first Hit when a search of the same spectrum is performed using the NIST Mass Spectral (MS) Search Program (National Institute of Standards and Technology, Gaithersburg, MD, USA) to search the NIST/EPA/NIH EI Mass Spectral Library (NIST 20) or the Wiley Registry of Mass Spectral Data, 12 th Edn (John Wiley & Sons, Hoboken, NJ, USA). 27 April 2020Ī collection of mass spectra of known compounds and the program used to search a spectrum of an unidentified compound are two different entities. Adjunct Professor of Chemistry and Director of the Pacific Mass Spectrometry Facility, Chemistry Department, University of the Pacific, Stockton, CA, USA.