Chirality detection

Other methods have been proposed for detecting chiral carbon atoms which do not rely on the CIP system, and which have been more convenient for some specific applications [108]. 

Detecting chirality centers in a complex molecule takes practice because it s not always immediately apparent that four different groups are bonded to a given carbon. The differences don t necessarily appear right next to the chirality center. For example, 5-bromodecane is a chiral molecule because four different groups are bonded to C5, the chirality center (marked with an asterisk). A butyl substituent is similar to a pentyl substituent but it isn t identical. The difference isn t apparent until four carbon atoms away from the chirality center, but there s still a difference. 

The separation mechanism is quite different from other chromatographic techniques and a broader spectrum of possible impurities can be detected at the same system (e.g., inorganic small cations, anions by indirect detection, chiral separations by adding a chiral selector, proteins and peptides by adding a polymer to the separation buffer, etc.)... 

Flapan, E. Topological Techniques to Detect Chirality in Mezey, P. G. Ed., New Developments in Molecular Chirality Kluwer Acad. Publ. Dordrecht, 1991, pp. 209-239. 

While chirality in a polymer side chain is easy to detect, chirality within a polymer chain is... 

Balmer, K. Persson, A. Lagerstrom, P.-O. Persson, B.-A. Schill, G. Liquid chromatographic separation of the enantiomers of metoprolol and its alpha-hydroxy metabolite on Chiralcel OD for determination in plasma and urine. J.Chromatogr., 1991, 553, 391-397 [plasma urine human dog extracted metabolites fluorescence detection chiral column temp 35 column temp 25 LOD 10 nM]... 

Methods for the Detection Chiral Analysis of Food Compounds Separated by CE... 

Pesticides and agrochemicals are mostly used in agriculture and in forestry activities. These chiral and nonchiral xenobiotics contaminate rivers during the course of rainfall and irrigation processes. However, some chiral pesticides have been reported at the poles and, hence, found in river water which comes from melting of snow at the poles. Another possibility for the presence of chiral pollutants in river water may be the dynamic exchange of pollutants between river water and the atmosphere (near agricultural fields). In view of this, some workers have tried to detect chiral pesticides in river water. 

Historically, the most common technique used to detect chirality and to distinguish enantiomers has been to determine whether a sample rotates plane polarized light. Optical activity and other chiroptical properties that can be measured using ORD and CD (see below) have long been essential for characterizing enantiomers. Their importance has lessened somewhat with the development of powerful NMR methods and chiral chromatographic methods, but their historical importance justifies a brief discussion of the methodology. 

Methods are required to detect chirality. A so-called chirality observation answers the question whether the system is chiral or not with yes or no. Then, a chirality measurement yields a value and a sign for a quantity that gives information about the chirality of the molecules or the phases but, in general, gives no measure for chirality itself. 

One of the most popular methods for detecting chirality is the measurement of the optical activity. A chiral object rotates the plane of polarization of linearly polarized light and generates ellipticity in the region of absorption bands because of the different refractive indices and absorption coefficients for left- and right-circularly polarized light - circular... 

The Rosetta Mission. The Rosetta spacecraft with the lander Philae is the first spacecraft to include an experiment to detect chiral molecules outside our planet. The spacecraft was named in honor of the Rosetta stone, which allowed Egyptian hierogl5q>hics to be translated, and resulted in... 

Jenkins AL, Hedgepeth WA. Analysis of chiral pharmaceuticals using HPLC with CD detection. Chirality 2005 17 S24-S29. 

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