Complexing chromatography

The rapid and reversible formation of complexes between some metal ions and organic compounds that can function as electron donors can be used to adjust retention and selectivity in gas and liquid chromatography. Such coordinative interactions are very sensitive to subtle differences in the composition or stereochemistry of the donor ligand, owing to the sensitivity of the chemical bond towards electronic, steric and strain effects. A number of difficult to separate mixtures of stereoisomers and isotopomers have been separated by complexation chromatography. 

Perhaps the most widely known example of complexation chromatography is the use of silver ions to complex organic... 

Figure 8.43 Separation of enantiomers using complexation chromatography. A, Separation of alkyloxiranes on a 42 m x 0.2S mm I.O. open tubular column coated with 0.06 M Mn(II) bis-3-(pentafluoro-propionyl)-IR-camphorate in OV-ioi at 40 C. B, Separation of D,L-amino acids by reversed-phase liquid chromatography using a mobile phase containing 0.005 M L-histidine methyl ester and 0.0025 M copper sulfate in an ammonium acetate buffer at pH 5.5. A stepwise gradient using increasing amounts of acetonitrile was used for this separation.

Analytical separation and spectroscopic techniques normally used for petroleum crudes and residues were modified and used to characterize coal liquids, tar sands bitumens, and shale oils. These techniques include solvent extraction, adsorption, ion-exchange, and metal complexing chromatography to provide discrete fractions. The fractions are characterized by various physical and spectroscopic methods such as GLC, MS, NMR, etc. The methods are relatively fast, require only a few grams of sample, provide compound type fractions for detailed characterization, and provide comparative compositional profiles for natural and synthetic fuels. Additional analytical methods are needed in some areas. 

Schurig, V., Biirkle, W., Zlatkis, A., and Poole C. F. (1979) Quantitative resolution of pyramidal nitrogen invertomers by complexation chromatography, Naturwissenschaften 66, 423. 

L. H. Klemm and D. Reed, Optical resolution by molecular complexation chromatography, I. Chromatogr. 3 (1959), 364. 

V. A. Davankov, Ligand exchange chromatography of chiral compounds, in D. Cagniant (ed.), Complexation Chromatography, Marcel Dekker, New York, 1992, p. 197. 

Organotin-stabiliser can be extracted from foodstuffs by various chlorinated solvents and hydrocarbons. Interfering substances, especially inorganic tin, were preseparated by paper chromatography After fusion and formation of the tin-catechol complex, chromatography was used for separation of the tin-complex from excess reagent. 

Nitrogen-containing compounds in shale oil were concentrated by FeCl3-clay complexation chromatography. Similarly the nitrogen compounds were also investigated from petroleum as well as coal liquids. 

Complexing Chromatography Liquid Solid Column Rapid and reversible formation of complexes... 

A limitation of silver ion complexation chromatography is the low upper temperature limit of the columns, 65°C or 40°C, as variously reported. Metal camphorate complexes have been used for both isomeric and enantiomeric... 

Toda procedure for obtaining enantiomeri-cally pure compounds will find broad application very soon. This development could make preparative HPLC with chiral columns obsolete and be applied to distillable amino acid derivatives as well. After all, analytical resolution of amino acids was quite successful by host/guest complexation chromatography with reversed-phase packings loaded with Cram s chiral 1,1 -binaphthyl crown ethers (similar to 1). [20]... 

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