Polysaccharide phases

J. Dingenen, Polysaccharide phases in enantioseparations in A practical approach to chiral separations by liquid chromatography, G. Subramanian, VCH, Weinheim (1994) Chapter 6. 

By clicking the appropriate buttons on the form, the user can combine molecular structure queries of sample, CSP and solvent, using operators AND, OR, NOT with data queries in one search. A query for the search of chiral separations of alpha-aromatic acids on any polysaccharide phases coated on silica gel providing an alpha value superior to 1.2 is shown in Eig. 4-4. 

Manipulation of mobile phase and temperature parameters can have some unusual effects on chiral separations. Variation of temperature and mobile phase composition has been reported to reverse the elution order on protein phases and polysaccharide phases (Persson and Andersson, 2001). 

In a comparative study of 102 racemates of pharmaceutical interest with the three techniques, HPLC, CE, and SEC, HPLC was found to have the highest coverage of enantioseparation [64]. The authors state that this probably arose partly as a result of a higher variety of phases being commercially available for HPLC. The phases with the widest application ranges in that study were found to be Chiralpak AD and Chiralcel OD and OJ (i.e., polysaccharide phases). 

A majority of the chiral purity assays made with HPLC published during the last decade are based on separation on CSPs and subsequent UV detection (Table 17.3). The polysaccharide phases seem to be the dominating CSPs, but there is an even distribution in the methods that uses normal-and reversed-phase modes. A few of the methods utilize CMPA [39,59,60] or indirect separation by chemical derivatization [16,18]. However, it seems that the majority of the published papers... 

The effect of substituents on the phenyl groups of cellulose tribenzoate has been studied [17]. Cellulose triphenylcarbamate derivatives are the most thoroughly investigated polysaccharide phases with respect to chiral resolution and its... 

Shibata T, Mori K, Okamoto Y, Polysaccharide phases, in Chiral Separations by HPLC (Krstulovic AM, Ed.) Ellis Horwood, New York, p. 336 (1989). 

Dingenen J, Polysaccharide phases in enantioseparations, in A Practical Approach to Chiral Separations by Liquid Chromatography (Subramanian G, Ed.), VCH Verlag, Weinheim, Germany, p. 115 (1994). 

Persson and Andersson [65] reviewed the unusual effects in liquid chromatographic separations of enantiomers on chiral stationary phases with emphasis on polysaccharide phases. On protein phases and Pirkle phases, reversal of the elution order between enantiomers due to... 

As adsorbate, the polysaccharide dct is sensitive to the DP and polydis-persity (Cohen Stuart et al., 1982). Higher DP polysaccharides are less kinetically active, are therefore slower to accumulate than lower DP polysaccharides because of the time taken for surface orientation, and are thus more inclined to stay adsorbed longer and reach higher concentrations. Agitation increases the rate of physical adsorption. From the foregoing discussion on polysaccharide dispersibility, it is safe to conclude that multilayer adsorption is antecedent to polysaccharide phase inversion and in some instances to sol-gel transition. 

The nature and the position of the substituents introduced into the benzene ring of the carbamate derivatives essentially define the chiral recognition ability of these CSPs [82]. Higher long-term stability of polysaccharide phases was achieved with covalent bonding of polysaccharide to the surface of the support [83]. 

Type V includes chiral stationary phases based on immobilized proteins as well as polysaccharide phases such as cellulose and amylose carbamate. They are used in conjunction with aqueous buffered mobile phases. The interaction between the stationary phase and the analytes is based on hydrophobic interaction as well as electrostatic interaction in the case of proteins. The retention of the analytes can be controlled by the addition of organic modifiers such methanol, ethanol, and 2-propanol. 

T. Shibata, K. Mori, and Y. Okamoto, Polysaccharide phases, in A. M. Krstulovic (ed.), Chiral Separation by HPLC. Applications to Pharmaceutical Compounds, Ellis Horwood, New York, 1989, P. 336. 

The number of available polysaccharide based CSPs coated on silica has increased in the last few years by the introduction of new carbamate substituents on cellulose and amylose or by the production of generic Daicel phases. All these CSPs in which the selector is coated on silica suffer from solvent restrictions. On the other hand, the recently introduced immobilized polysaccharide phases Chiralpak lA (05JC(A1075)65, 05LOC433), IB, and IC allow a large range of eluents that were not permitted for the coated versions. 

Fig. 8. From left to right schematic representation of pure and coated polysaccharide phases, brush-type phase, protein phase.

Table S Typical mobile phases for immobilized polysaccharide phases...

For polysaccharide phases, the history of the column can have a decisive effect. 

SchUl G, Wainer IW, Barkan SA (1986) Chiral separations of cationic and anionic drugs on an al-add glycoprotein-bonded stationary phase (Enantio-Pac). II. Influence of mobile phase additives and pH on chiral resolution and retention. J Chromatogr 365 73-88 Shibata T, Mori K, Okamoto Y (1989) Polysaccharides phases. In Krstulovic AM (ed) Chiral separations by HPLC. EHis Horwood, New York, pp 336-398... 

Ligaments are dense connective tissnes constituted by a protein phase (collagen and elastin) and a polysaccharide phase (proteoglycans). The elastic modulus of ligament is about 150-355MPa, and the tensile strength is less than 50MPa. Their mechanical properties are determined by the relative amount of the two phases as... 

First, the partition of hydrophobized polysaccharide (HP)-coated liposomes was investigated in aqueous two-phase systems such as polyfethylene oxide) (PEO) (top phase)/pullulan (bottom phase) and poly(ethylene oxide) (top)/ dextran (bottom phase). HPs such as cholesterol-bearing pullulan, dextran, and mannan nicely coated the liposomal surface. When conventional uncoated liposomes were added to the aqueous two-phase system, they mostly located at the interface between the two polymer phases. The HP-coated liposomes, on the other hand, were significantly partitioned into the bottom polysaccharide phase, depending on the structure of the HP on the liposomal surface. 

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