Fingerprint compound

In the last paragraph of Section 12.8.2, we saw in the case of xylene isomers that even the great compound fingerprinting capability of full scan MS detection could not distinguish... 

Cavazza, A., Corradini, C., Musci, M., and Salvadeo, P. 2012. High-performance liquid chromatographic phenolic compound fingerprint for authenticity assessment of honey. J. Sci. Food Agric. 93 1169-1175. 

Ruiz-Samblas, C., Tres, A., Koot, A. et al. (2012) Proton transfer reaction-mass spectrometry volatile organic compound fingerprinting for monovarietal extra virgin olive oil identification. Food Chem. 134, 589. 

De Bok, F.A.M., Janssen, P.W.M., Bayjanov, J.R., et al. (2011) Volatile compound fingerprinting of mixed-culture fermentations. Appl Environ Microbiol 77,6233-6239. 

He therefore wanted to synthesise TM 29 to check. Even with modem spectroscopic methods the quickest way to check the identity of a compound will often be to synthesise it by an unambiguous route and compare the n.m.r. and fingerprint i.r. spectra. How then would you make TM 29 ... 

The mass spectrum is a fingerprint for each compound because no two molecules are fragmented and ionized in exactly the same manner on electron-impact ionization. In reporting mass spectra the data are normalized by assigning the most intense peak (denoted as base peak) a value of 100. Other peaks are reported as percentages of the base peak. 

The fragment ions are characteristic of any given substance in that the way a compound fragments can be regarded as a fingerprint. For the fragment ions to be useful, it is necessary to know how they relate to each other. In other words, it is necessary to understand which fragment should be connected to which others in the overall chemical structure. 

In view of the magnitude of crystal-field effects it is not surprising that the spectra of actinide ions are sensitive to the latter s environment and, in contrast to the lanthanides, may change drastically from one compound to another. Unfortunately, because of the complexity of the spectra and the low symmetry of many of the complexes, spectra are not easily used as a means of deducing stereochemistry except when used as fingerprints for comparison with spectra of previously characterized compounds. However, the dependence on ligand concentration of the positions and intensities, especially of the charge-transfer bands, can profitably be used to estimate stability constants. 

The need for an overall and combined chemical structure and data search system became clear to us some time ago, and resulted in the decision to build CHIRBASE, a molecular-oriented factual database. The concept utilized in this database approach is related to the importance of molecular interactions in chiral recognition mechanisms. Solely a chemical information system permits the recognition of the molecular key fingerprints given by the new compound among thousands of fingerprints of known compounds available in a database. 

FI CU RE 35.12 Typical fingerprint of a masterbatch mixing process on an intermeshing internal mixer (GK 320E (Harburg Freudenberger) with PES5 rotors styrene-butadiene rubber/carbon black [SBR/CB] tread compound). 

Results of a Fingerprint Analysis of a Masterbatch and Remill Mixing Process of a Styrene-Butadiene Rubber-Carbon Black (SBR-CB) Compound on a CK320E Intermeshing Mixer with PES3 Rotors (Harburg Freudenberger)... 

The basis of this technique is absorption of ir radiation by molecules over a wide spectrum of wavelengths to give a characteristic fingerprint spectrum providing both qualitative and quantitative data on the substance. This versatile technique owes its success in occupational hygiene to the development of a portable spectrometer. Table 9.8 lists some compounds detectable by one type of portable ir analyser. 

Clustering is the process of dividing a collection of objects into groups (or clusters) so that the objects within a cluster are highly similar whereas objects in different clusters are dissimilar [41]. When applied to databases of compounds, clustering methods require the calculation of all the pairwise similarities of the compounds with similarity measures such as those described previously, for example, 2D fingerprints and the Tanimoto coefficient. 

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