Chemical fingerprint-profiling

To detect adulteration of wine. Bums et al. (2002) found that the ratios of acetylated to p-coumaroylated conjugates of nine characteristic anthocyanins served as useful parameters to determine grape cultivars for a type of wine. Our laboratory utilized mid-infrared spectroscopy combined with multivariate analysis to provide spectral signature profiles that allowed the chemically based classification of antho-cyanin-containing fruits juices and produced distinctive and reproducible chemical fingerprints, making it possible to discriminate different juices. " This new application of ATR-FTIR to detect adulteration in anthocyanin-containing juices and foods may be an effective and efficient method for manufacturers to assure product quality and authenticity. 

SPME, coupled with GCMS, has been used to characterize impurities in illicit methamphetamine samples placed in a sealed headspace vial (70). This method works well for generating material fingerprint profiles in methamphetamine samples. The detection and characterization of increased points of comparison by this method as compared to a conventional solvent extraction provides more detailed chemical signatures for both intelligence and operational information. 

Metabolomics is the systematic study of the chemical fingerprints left by specific cellular processes. The metabolome is the collection of all the metabolites of a biological organism, which are the final product or products of metabolic reactions that occur in a body. While the data of proteomic analyses do not explain fully what might happen in a cell, the metabolic profile may provide a snapshot of the physiology of that cell. This analysis allows one to verify... 

As illustrated in the next section, the use of biological fingerprints, such as from a BioPrint profile, provides a way to characterize, differentiate and cluster compounds that is more relevant in terms ofthe biological activity of the compounds. The data also show that different in silico descriptors based on the chemical structure can produce quite different results. Thus, the selection of the in silico descriptor to be used, which can range from structural fragments (e.g. MACCS keys), through structural motifs (Daylight keys) to pharmacophore/shape keys (based on both the 2D structure via connectivity and from actual 3D conformations), is very important and some form of validation for the problem at hand should be performed. 

Fig. 18.8 Similarity profile for filtered set of commercially available compounds. 5000 randomly selected compounds from the Available Chemicals Directory that pass the REOS filter were ranked according to their Tanimoto similarity scores (vertical axis) using Daylight fingerprints. 2886 compounds (58%) had similarity scores below 0.85.

Fig. 15.14 Analytical techniques for time-resolved headspace analysis. An electronic nose can be used as a low-cost process-monitoring device, where chemical information is not mandatory. Electron impact ionisation mass spectrometry (EI-MS) adds sensitivity, speed and some chemical information. Yet, owing to the hard ionisation mode, most chemical information is lost. Proton-transfer-reaction MS (PTR-MS) is a sensitive one-dimensional method, which provides characteristic headspace profiles (detailed fingerprints) and chemical information. Finally, resonance-enhanced multiphoton ionisation (REMPI) TOFMS combines selective ionisation and mass separation and hence represents a two-dimensional method. (Adapted from [190])...

The introduction of non-volatile components into an MS has typically been via the pyrolysis of whole fermentation liquors. Pyrolysis is the thermal degradation of a material in an inert atmosphere or a vacuum. It causes molecules to cleave at their weakest points to produce smaller, volatile fragments called pyrolysate [23]. An MS can then be used to separate the components of the pyrolysate on the basis of their mass-to-charge ratio (m/z) to produce a pyrolysis mass spectrum, which can then be used as a chemical profile or fingerprint of the complex material analysed [24]. 

Omiecinski, C. J. University of Washington Fingerprinting of cytochrome P-450 profiles as biomarkers of chemical exposure NIEHS... 

Explicitly developed are models of several theoretical multiphase distributions, with corresponding depth-profile results on thin-film plasma polymers, phase-separated block copolymers, and chemical reactions on fiber surfaces. Ion impact is treated from three points of view as an analytical fingerprint tool for polymer surface analysis via secondary ion mass spectroscopy, by forming unique thin films by introducing monomers into the plasma, and as a technique to modify polymer surface chemistry. 

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