Wiley mass spectral library

Data were acquired under the following GC conditions inlet temperature 150 C, carrier gas helium at 1.1 mL/min, split ratio 1 2, detector temperature 280 C, temperature program initial temperature 2 C, initial time 4 min, rate 20 C/min to 50 C then 5°C/min, final temperature 250 C, final time 2 min. The MS was held at 190 C in the ion source using ionization energy of 70 eV and a scan rate of 0.9 scans/s. Tentative identities were assigned to peaks with respect to the Wiley mass spectral library. 

Each of the aromatic compounds analysed was identified by means of its retention time, coeluted with a standard solution of the commercial product and confirmed by mass spectrometry (Hewlett-Packard 5972 MSD, Palo Alto, CA, USA). Positive ion electron impact mass spectra were acquired in scan mode, with a range of nVz 39-300 and a scan-rate of 1.6 scan s-i. For each compoimd the mass spectra was confirmed by comparison with the Wiley mass spectral library. The chromatographic column, injector and oven temperatures, carrier gas and its flow, were the same as those used for the quantification, as described below. 

Hewlett-Packard Mass Selective Detector (MSD)(HP 5971A). The ion source was run in the El mode at 170 °C using an ionisation energy of 70 eV. The scan rate was 0.9 scans/sec. Data from the MSD was stored and processed using a Hewlett-Packard Vectra QS20 computer installed with Mustang software and the Wiley Mass Spectral Library. Kovats indices were calculated against extemd hydrocarbon standards. Concentrations were determined from the internal standard, butyl hexanoate, and are not corrected for detector response. 

Mass Spectral Library[35] and the Wiley Registry of Mass Spectral Data[36] are now available to help mass spectrometrists in the identification of unknowns. 

Provided El spectra have been measured under some sort of standard conditions (70 eV, ion source at 150-250 °C, pressure in the order of 10 " Pa), they exhibit very good reproducibility. This is not only the case for repeated measurements on the same instrument, but also between mass spectrometers having different types of mass analyzers, and/or coming from different manufacturers. This property soon led to the collection of large El mass spectral libraries, either printed [76-78] or computerized. [79] The best established El mass spectral databases are the NIST/EPA/NIH Mass Spectral Database and the Wiley/NBS Mass Spectral Database, each of them giving access to about 120,000 evaluated spectra. [80-83]... 

GC/MS was the primary tool for identifying the first DBFs, and it remains an important tool for measuring and identifying new DBFs. Large mass spectral libraries (NIST and Wiley databases, which contain >200,000 spectra) enable rapid identifications. When DBFs are not present in these databases, high-resolution... 

The Wiley Registry of Mass Spectral Data, commercially available at John Wiley Sons, Inc., http //www.wiley.com/cda/ product/0 0471515930 desc 3047,00.html - The NIST98-NIST/EPA/NIH Mass Spectral Library, commercially available at the National Institute of Standards and Technology, http //www.sisweb.com/software/ ms/nist98.htm) and... 

Chemicals for which no GC/EIMS library spectra was available in the OPCW Central Analytical Database (OCAD), the Wiley Registry of Mass Spectral Data, and the NIST98-NIST/EPA/NIH Mass Spectral Library, at the time of the proficiency test... 

NIST/EPA/NIH. 2011. NIST/EPA/NIH Mass Spectral Library. John Wiley Sons. 

When the GC/MS analysis is done following a derivatization such as silylation, the differentiation of the two types of compounds is not simple because only a limited number of spectra for derivatized compounds is available. For example, in common mass spectral libraries (NBS, Wiley) only the spectrum of the TMS derivative of (non substituted) diketopiperazine is reported (see Figure 12.2.2) and not that of the corresponding imidazolindione. Therefore, not knowing the spectrum It is difficult to decide if certain imidazolindiones are present or not together with DKPs in the chromatograms of silylated pyrolysates of peptides. 

The peak identification for the chromatogram shown in Figure 6.1.25 was done using MS spectral library searches. This identification is not always possible, since most compounds with a higher MW are not found in the commercial mass spectral libraries (such as NIST 2002, Wiley 7. etc.). The similarity between the spectra in each series of compounds can be used for peak identification, even when the compound is not found in the mass spectral library. This is exemplified in Figure 6.1.26, which shows the spectra of the B series of compounds shown in Table 6.1.10. 

The pyrogram of poly(2-vinylpyridine-co-styrene) is typical for a random copolymer. Both styrene and 2-vinylpyridine monomers as well as their dimers are present in the pyrogram (see also Section 6.5 for pyrolysis of poly(2-vinylpyridine)). In addition, AB types compounds are seen in the pyrogram. The spectra of 2-(3-phenylbut-3-enyl)pyridine and of 2-[1-(2-phenylethyl)vinyl]pyridine are shown in Figure 6.2.12 and 6.2.13. These spectra are not available In common mass spectral libraries (Nist 98, Wiley 275, etc.). 

The spectrum of 2-methyl-2-propenoic acid dodecyl ester is available in commercial mass spectral libraries (NIST 2002, Wiley 7 and previous versions) and is shown in Figure 6.7.36. 

The current mass spectral libraries (NIST 2002, Wiley 7) do not contain the spectra of these compounds, and therefore they were not identifiable by the MS library searches. The use of mass spectrum fragments can be of help in these situations. One example is the tentative identification for the peak with retention time of 75.48 min. (from Figure 6.9.2) as 4-methyl-1 - 1 -methyl-1 -[2-methyl-5-(methylethyl)cyclohexyl]ethyl benzene. The fragment assignments for the ions seen in the mass spectrum are shown in Figure 6.9.3. 

Wiley). For example, the spectrum of undecamethylphenylcyclohexasiloxane is not available, and the spectrum for nonamethylphenylcyciopentasiloxane given only in Wiley 4 mass spectral library does not show ions with m/z > 400 a.u. The spectra of two compounds available in Wiley 6. namely pentamethylphenylcyclotrisiloxane and heptamethylphenyicyclotetrasiloxane are shown in Figure 16.1.3a, and those of undecamethylphenylcyclohexasiloxane and nonamethylphenylcyclopentasiloxane are shown in Figure 16.1.3b. 

The analysis of essential oil components was performed by GC/MS analysis. Individual identifications were made by matching their spectra with those from mass spectral libraries (Wiley 275.L) and the identity of each component was confirmed by comparison of its Kovat s index (72) with those from hterature(73) (Table 111). Individual oil constituents were reported as relative percent of total essential oil. 

Identification of individual compounds was based on comparison of EC-mass spectra with those of reference compounds, mass spectral data bases (NIST/EPA/NIH Mass Spectral Library NIST2000, Wiley/NBS Registry of Mass Spectral Data, 7th Ed., electronic versions) and gas chromatographic retention times, elution patterns or retention indices (e.g. Vassilaros et al., 1982 Rostad and Pereira, 1986 Ballschmitter et al. 1987, Bundt et al., 1991 Paschke et al., 1992 Peters and Moldowan, 1993 Wang et al., 1994). For correction of injection time inaccuracies the retention times of the internal standard compounds were used. 

Mass spectrometers can readily be interfaced to GC (Figure 4.21). As the compounds leave the chromatograph, they are introduced into the mass spectrometer operating in a vacuum. The great majority of GC-MS are benchtop instruments with linear quadrupoles and EL Compound identification is performed by comparison of the spectrum with a data base for precise identification and confirmation. Huge El mass spectral libraries such as NIST Library or Wiley Library contain... 

Combined GC-MS is the standard technique used for identifying cuticular waxes, and electron ionization (El) is the most widely used MS ionization technique in their analysis. The most frequent and simple method of identification involves comparison of the recorded mass spectra with those in standard mass spectral libraries or with those of authentic standards. Unfortunately, the spectra of wax constituents are rarely published in MS libraries (e.g. NIST Chemistiy WebBook, Wiley Registry of Mass Spectral Data, MSDC). For compounds that remain unidentified in the above MS libraries, the mass sp>ectra found in the literature can be consulted. Table 2 gives the references of published mass spectra or fragmentation patterns for some less common cuticular wax components. 

The composition is determined based on relative response in the chromatograms. The identification of each component is based on direct comparison of the retention time and mass spectral fragmentation with the data published by Adams [12] and others [13-16]. The mass spectral library fit (Wiley 139 Library) for all identified components was more than 90%. It should be mentioned that the GC column used in this study (Rtx -5, 30m x 0.25 mm, 0.25pm film thickness) was similar to that reported by Adams [12]. 

The great majority of today s GC-MS applications ntiUze one-dimensional capillary GC with quadrupole MS detection and electron ionization. Nevertheless, there are snbstantial numbers of applications using different types of mass spectrometers and ionization techniqnes. The proliferation of GC-MS applications is also a result of conunercially available easy-to-handle dedicated mass spectral libraries (e.g., NIST/EPA/NIH 2005 WILEY Registry 2006 MassFinder 2007 and diverse printed versions such as Jennings and Shibamoto, 1980 Joulain and Konig, 1998 and Adams, 1989, 1995, 2007 inclusive of retention indices) providing identification of the separated componnds. However, this type of identification has the potential of prodndng some unreliable resnlts, if no additional information is used, since some compounds, for example, the sesquiterpene... 

F, W, McLafferiy. Wt/ey Registry of Mass Spectral Data. 7ih ed.. New York Wiley, 2000. It is also available combined vsith S lST Mass Spectral Library, on CD-ROM,... 

The Wiley Registry of Mass Spectral Data has been published in its 10th Edition (John Wiley Sons, 2013, Editor Fred W. McLafferty) (McLafferty and Stauffer, 1989). It is the largest and most comprehensive mass spectral library ever made commercially available in the most common mass spectrometry software formats and compatible with most manufacturer data systems. Applications include pathology, toxicology, forensics, quality assurance, border control, research and development, food safety and environmental sciences. The 10th edition of the Wiley Registry contains ... 

For either analytical approach, identification of the diagnostic cure system breakdown species is by reference to mass spectral libraries such as those produced by the National Institute of Standards and Technology (USA) (NIST), the Royal Society of Chemistry, Wiley/NBS (a. 12) and the US Environmental Protection Agency (EPA)/National Institute of Health (NIH). The mass spectra of the majority of species of interest are in these libraries and so, providing the knowledge to reconstmct cure systems is available, successful attempts can be made. 

Today, GC-MS (see Section 4.1.1) is a golden standard for detection and quantification of drugs and poisons volatile under GC conditions, whereas nonvolatile compounds require LC-MS (see Section 4.1.2). The GC-MS technique is much more popular for identification purposes than LC-MS, because of the easy availability of the reference mass spectra for many xenobiotics and their derivatives, either in printed or computer form. The most popular libraries are the NIST library, which contains the mass spectra of 130,000 compounds, the Wiley Registry of Mass Spectral Data, which contains 390,000 reference spectra, and the Pfleger-Maurer-Weber library, with 6,300 mass spectra and other data, such as chromatographic retention indexes. 

Focus identification on the odor-active regions as determined by GC-sniffing and RI values as published in the Flavomet (http //www.nysaes.cornell.edu/flavornet). The fragmentation pattern obtained for the compounds can be compared with those in data banks like the Wiley/NBS Registry of Mass Spectral data (McLafferty and Stauffer, 2000) or the NIST 98 library (National Institute of Science and Technology). 

An excellent collection of NMR and IR spectra for reference purposes is found in The Aldrich Library of 13 C and 1H FT NMR Spectra and The Aldrich Library of Infrared Spectra. Both are available in most libraries and the former can be purchased from Aldrich Chemical Co. A variety of compilations of mass spectral data are available seeF. S. McLafferty and D. B. Stauffer, The Wiley/NBS Registry of Mass Spectral Data, 5th ed., Wiley Interscience, New York, 1988. 

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