High-performance liquid chromatography optical isomers

Immobilization. The ability of cyclodextrins to form inclusion complexes selectively with a wide variety of guest molecules or ions is well known (1,2) (see Inclusion COMPOUNDS). Cyclodextrins immobilized on appropriate supports are used in high performance liquid chromatography (hplc) to separate optical isomers. Immobilization of cyclodextrin on a solid support offers several advantages over use as a mobile-phase modifier. For example, as a mobile-phase additive, p-cyclodextrin has a relatively low solubility. The cost of y- or a-cyclodextrin is high. Furthermore, when employed in thin-layer chromatography (dc) and hplc, cyclodextrin mobile phases usually produce relatively poor efficiencies. 

K. Shimizu, T. Kakimoto, K. Ishi, Y. Fujimoto, H. Nishi, and N. Tsumagari, New derivatization reagent for the resolution of optical isomers in diltiazem hydrochloride by high-performance liquid chromatography, J. Chromotogr., 357 119 (1986). 

Nagai, T., Kamiyama, S., Nagai, T., Forensic Toxicologic Analysis of Methamphetamine Optical Isomers by High Performance Liquid Chromatography, Z. Rechtsmed., 101,151,1988. 

W. H. Pirckle, D. W. House, and J. M. Firm. Broad spectrum resolution of optical isomers using chiral high performance liquid chromatography bonded phases. J. Chromatogr. A 192 (1980) 143. 

Weems, H. B. and Yang, S. K. (1982) Resolution of optical isomers by chiral high performance liquid chromatography separation of dihydrodiols and tetrahydrodiols ofbenzo[a]pyreneandbenz[a]anthracene. na/ Biochem. 125, 156-161. 

Ito, M. Kuriki, T. Goto, J. Nambara, T. Separation of ramipril optical isomers by high-performance liquid chromatography. J.Liq.Chromatogr., 1990, 13, 991-1000... 

S. Lam and A. Karmen, Resolution of optical isomers of Dns-amino acids by high-performance liquid chromatography with L-histidine and its derivatives in the mobile phase,/. Chromatogr, 1982, 239, 451-462. 

Although overcrowded afkenes are attractive due to the efficient switching of LC handedness, the delicate synthesis of overcrowded alkenes remains a limitation for their practical applications. Normally the separation of two enantiomers of crude racemic product to obtain optically pure isomer has to rely on the preparative high performance liquid chromatography (HPLC), which is not suitable for a large-scale preparation. Consequently, researchers are seeking for other types of photoresponsive molecules for the switching of helix handedness. 

Oi N, Horiba M, Kitahara H (1981) Gas chromatographic separation of optical isomers of chrysanthemic acid on an optically active stationary phase. Agric Biol Chem 45(6) 1509-1510 Oi N, Kitahara H, Kira R (1990) Enantiomer separation of pyrethroid insecticides by high-performance liquid chromatography with chiral stationary phases. J Chromatogr A 515 441 50... 

Kinoshita Y, Yamamoto Y, Yoshimura 1, Kurokawa T, Huneck S (1997) Distribution of Optical Isomers of Usnic and Isousnic Acids Analyzed by High Performance Liquid Chromatography. J Hattori Bot Lab 83 173... 

In the available literature concerning the determination of chiral products by separation techniques, consistent opinion of the authors about the application of thin-layer chromatography (TLC) for the analysis of optical isomers is observed in many cases when column techniques such as high-performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrophoresis (CE) are in competition [1-3]. 

Cyclodextrins have previously been successfully employed in separation science. For instance, the partial separation and enrichment of optical and structural isomers as well as routine compounds based on selective precipitation with CDs have been reported [5,7-8]. Additionally, solutions of CDs have served as the mobile phase in a few thin-layer and high performance liquid chromatographic separations [5,9,10]. However, their most widespread application in chromatography has been as part of the stationary phase [5,6]. Various polymeric CD materials, CD gels or resins, as well as CD coated columns have been utilized as the stationary phases in the separation of many important classes of compounds [5,6,11-13]. Unfortunately, the use of these CD phases has been largely restricted to column or gas chromatography due to their low efficiency and/or poor mechanical strength [14-16]. 

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