Fingerprinting, chemical sample

FIGURE 2 GC-MS/MS chemical fingerprint (product ion spectrum) of (a) standard muramic acid (2ng total in sample) and (b) muramic acid isolated from dust. Medical samples appear similar. 

Many applications which use Ge(Li) spectra of irradiated samples for identification purposes as a type of "chemical fingerprint have recently appeared in the literature. The potential of this technique in the fields of forensics, archeology, and detection of art forgeries is just beginning to be explored. 

Many other important application areas of chemometrics have been the subject of reviews and are too numerous to list here. A sampling of reviews in this category illustrates the breadth and diversity of chemometrics application areas. A review of applications in smart sensors [54] describes how chemometrics is an important enabling technology for the development of smart and reliable sensor systems. A review of environmental forensics [55] describes how numerical methods are critical in the process of identifying the chemical fingerprints of complex contaminant sources in environmental systems. Often, multiple sources are present at different geographic sites. By use of appropriate chemometric methods, these mixtures of different sources can be mathematically resolved to identify them and map their temporal and spatial distributions. 

The chemist also wishes to relate samples in a similar manner. Can protein sequences from different animals be related and does this tell us about the molecular basis of evolution Can the chemical fingerprint of wines be related and does this tell us about the origins and taste of a particular wine Unsupervised pattern recognition employs a number of methods, primarily cluster analysis, to group different samples (or objects) using chemical measurements. 

Marker B (1994b) Inorganic chemical fingerprinting of the environment reference freshwater - a useful tool for comparison and harmonization of analytical data in freshwater chemistry. Eresenius J Anal Chem 349 697-702 Marker B (1996) Instrumental element and multi-element analysis of plant samples - methods and applications. WUey, Chichester/New York... 

The histidine kinase assay was used to test 64,000 microbial fermentation (NatChem ) extracts, of which 1.8% was found to be active. Active samples were first prioritized on the basis of their potency and selectivity of action for histidine kinase with respect to an unrelated protein kinase. After chemical fingerprinting by high-performance liquid... 

Since Sleeter s review, several cases have been tried using chemical fingerprinting to determine the source of an oil spill. The three cases tried in 1977 emphasized the importance of documentation, beginning with the taking of the sample (long before the chemist becomes involved) and requiring an unbroken chain of custody until the sample is disposed of. 

Authentication of pjropohs material may be possible by a chemical fingerprint of it and, if possible, of its botanical sources. Thus, chemical fingerprinting, i.e., metabolomics and chemometrics, is an additional method that has been claimed to be included as a quality control method in order to confirm or deny the ptropohs sample being used for the manufacturing of a derived product of that resinous and complex matrix. 

In any chemical separation scheme, the original sample becomes divided into at least two firactions through the application of a driving force across a functional boundary in such a way that the resulting firactions have a chemical fingerprint that is distinctly different from that of the initial sample. Typical driving forces are concentration gradients, solvent flow, or electrochemical potential. Typical separation boundaries include immiscible liquid-liquid or liquid-solid interfaces. The effectiveness of the separation of contaminant A from desired material B can be expressed in terms of a decontamination factor D ... 

Sandercock, P.M.L., DuPasquier, E. (2004) Chemical fingerprinting of gasoline. 3. Comparison of unevaporated automotive gasoline samples from Austraha and New Zealand. Forensic Sci. Int., 140(1), 71-77. 

Can be used with solids and liquids No sample preparation needed Not interfered by water Non-destructive Highly specific like a chemical fingerprint of a material Raman spectra are acquired quickly within seconds... 

The key to this work is DNA—the chemical fingerprint present in every tissue of every individual. Although the general structure of DNA is the same from one person to another, evidence for familial ties is present in the detailed sequence of each person s DNA. With the use of relatively simple chemistry—involving fluorescent dyes or radioactive isotopes, enzymes, gel electrophoresis, and a process called the polymerase chain reaction (PCR) that earned its inventor the 1993 Nobel Prize in Chemistry (Section 25.8)—it is now easy to synthesize millions of copies from a sample of DNA and to sequence it rapidly and conveniently. Application of these tools to comparison of DNA samples from victims and relatives provides hope that, at least in some cases, the gap between family members will be closed. 

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