Chiral phases macrocyclic glycopeptides

Method Development and Optimization of Enantiomeric Separations Using Macrocyclic Glycopeptide Chiral Stationary Phases... 

Chirobiotic Handbook, Guide to using macrocyclic glycopeptide bonded phases for chiral LC separations, Advanced Separation Technologies Inc. (ASTEC), 2nd Ed. Whippany, New York... 

Because plasma and urine are both aqueous matrixes, reverse-phase or polar organic mode enantiomeric separations are usually preferred as these approaches usually requires less elaborate sample preparation. Protein-, cyclodextrin-, and macrocyclic glycopeptide-based chiral stationary phases are the most commonly employed CSPs in the reverse phase mode. Also reverse phase and polar organic mode are more compatible mobile phases for mass spectrometers using electrospray ionization. Normal phase enantiomeric separations require more sample preparation (usually with at least one evaporation-to-dryness step). Therefore, normal phase CSPs are only used when a satisfactory enantiomeric separation cannot be obtained in reverse phase or polar organic mode. 

Ahoul-Enein, H.Y. and Ali, I. Macrocyclic glycopeptide antihiotics-hased chiral stationary phase, in Chiral Separation by Liquid Chromatography and Related Technologies, Marcel Dekker New York, 2003, chap. 2. 

Staroverov, S.M. et al.. New chiral stationary phase with macrocyclic glycopeptide antibiotic eremomycin chemically bonded to sihca, J. Chromatogr. A, 1108, 263, 2006. 

Petrusevska, K. et al.. Chromatographic enantioseparation of amino acids using a new chiral stationary phase based on a macrocyclic glycopeptide antibiotic, J. Sep. ScL, 29, 1447, 2006. 

Berthod, A. et al.. Evaluation of the macrocyclic glycopeptide A-40,926 as a high-performance liquid chromatographic chiral selector and comparison with teicoplanin chiral stationary phase, J. Chromatogr. A, 897, 113, 2000. 

Beesley, T.E., Lee, J.T., and Wang, A.X., Method development and optimization of enantiomeric separations using macrocyclic glycopeptide chiral stationary phases, in Chiral Separation Techniques, Second completely revised and updated edition, Subramanian, G., Ed., Wiley-VCH Weinheim, 2001, 25. 

Xiao, T.L., Reversal of enantiomeric elution order on macrocyclic glycopeptide chiral stationary phases, J. Liq. Chrom. Rel. TechnoL, 24, 2673, 2001. 

Sztojkov-lvanov, A. et al., Comparison of separation efficiency of macrocyclic glycopeptide-based chiral stationary phases for the LC enantioseparation of fi-amino acids, Chromatographia, 64, 89, 2006. 

Xiao, T.L. et al.. Separation of enantiomers of substituted dihydrofurocoumarins by HPLC using macrocyclic glycopeptide chiral stationary phases, Anal. Bioanal. Chem., 377, 639, 2003. 

Figure 4.10 shows the effect of additive concentration on the separation of clen-buterol enantiomers on a polysaccharide-based chiral stationary phase [79]. The peak shapes were dramatically improved by adding an amine additive and the separation time was also reduced from 14 to 7 min when 1.0% amine was added to the mobile phase. Phinney and Sander [100] investigated the effect of amine additives using chiral stationary phases having either a macrocyclic glycopeptide or a... 

Chirobiotic Handbook, Guide to Using Macrocyclic Glycopeptide Bonded Phases for Chiral LC Separations, 2nd ed., Advance Separation Tech. Inc., Whippany, NJ,... 

The most popular and commonly used chiral stationary phases (CSPs) are polysaccharides, cyclodextrins, macrocyclic glycopeptide antibiotics, Pirkle types, proteins, ligand exchangers, and crown ether based. The art of the chiral resolution on these CSPs has been discussed in detail in Chapters 2-8, respectively. Apart from these CSPs, the chiral resolutions of some racemic compounds have also been reported on other CSPs containing different chiral molecules and polymers. These other types of CSP are based on the use of chiral molecules such as alkaloids, amides, amines, acids, and synthetic polymers. These CSPs have proved to be very useful for the chiral resolutions due to some specific requirements. Moreover, the chiral resolution can be predicted on the CSPs obtained by the molecular imprinted techniques. The chiral resolution on these miscellaneous CSPs using liquid chromatography is discussed in this chapter. 

Although the macrocyclic glycopeptide antibiotic CSPs are very effective for the chiral resolution of many racemic compounds, their use as chiral mobile phase additives is very limited. Only a few reports are available on this mode of chiral resolution. It is interesting to note that these antibiotics absorb UV radiation therefore, the use of these antibiotics as the CMPAs is restricted. However, Armstrong et al. used vancomycin as the CMPA for the chiral resolution of amino acids by thin-layer chromatography, which will be discussed in Section 10.7. 

The chiral recognition mechanisms in NLC and NCE devices are similar to conventional liquid chromatography and capillary electrophoresis with chiral mobile phase additives. It is important to note here that, to date, no chiral stationary phase has been developed in microfluidic devices. As discussed above polysaccharides, cyclodextrins, macrocyclic glycopeptide antibiotics, proteins, crown ethers, ligand exchangers, and Pirkle s type molecules are the most commonly used chiral selectors. These compounds... 

Aboul-Enein, H. and Ali, I. (2002) Optimization Strategies for HPLC Enantioseparation of Racemic Drugs Using Polysaccharides and Macrocyclic Glycopeptide Antibiotic Chiral Stationary Phases, Farmaco 57, 513-529. 

Analytical Properties Substrate has 38 chiral centers and 7 aromatic rings surrounding 4 cavities (A, B, C, D), making this the most structurally complex of the macrocyclic glycopeptides substrate has a relative molecular mass of 2066 this phase can be used in normal, reverse, and polar organic phase separations selective for anionic chiral species with polar organic mobile phases, it can be used for a-hydroxy acids, profens, and N-blocked amino acids in normal phase mode, it can be used for imides, hydantoins, and N-blocked amino acids in reverse phase, it can be used for a-hydroxy and halogenated acids, substituted aliphatic acids, profens, N-blocked amino acids, hydantoins, and peptides Reference 47, 48... 

Berthod et al. [28] examined the effect of temperature on chiral separations between 5°C and 45°C using four macrocyclic glycopeptides phases and although the efficiencies increased with temperature, in 83% of cases the chiral selectivity decreased. 

The group of Bakhtiar [57-59] described the chiral bioanalysis of MPH in various matrices, utilizing a number of sample pretreatment strategies, separation on a Chirobiotic V columns, and the use of positive-ion APCI-MS in SRM mode. The chiral selectivity of the Chirobiotic V column is based on the use of the macrocyclic glycopeptide antibiotic vancomycin. The column can be used in both aqueous and organic mobile phase. 

W. S., Armstrong, D. W. Separation of chiral sulfoxides by liquid chromatography using macrocyclic glycopeptide chiral stationary phases, J. Chromatogr. 

Liu,Y., Berthod, A., Mitchell, C. R., Xiao,T. L., Zhang, B., Armstrong, D. W. Super/subcritical fluid chromatography chiral separations with macrocyclic glycopeptide stationary phases, J. Chromati. A, 2002, 978, 185-204. 

Chiral mobile phase additives provide a more versatile and cost-effective approach for enantiomer separations in thin-layer chromatography. Typically, chemically bonded layers with cyclodextrin and its derivatives, bovine serum albumin, or macrocyclic glycopeptides are used as chiral additives in the reversed-phase mode [59,60,172-178]. For [5- and y-cyclodextrins and their derivatives, a 0.1 to 0.5 M aqueous methanol or acetonitrile solution of the chiral selector is used as the mobile phase. Bovine serum albumin is generally used at concentrations of 1-8 % (w/v) in an aqueous acetate buffer of pH 5 to 7 or in a 0.5 M acetic acid solution, in either case with from 3-40 % (v/v) propan-2-ol (or another aliphatic alcohol), added to control retention. Enantioselectivity usually increases with an increase in concentration of the chiral selector, and may be non existent at low concentrations of the chiral selector. 

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