Stationary phases matrix support

Reversed-phase chromatography employs a nonpolar stationary phase and a polar aqueous-organic mobile phase. The stationary phase may be a nonpolar ligand, such as an alkyl hydrocarbon, bonded to a support matrix such as microparticulate silica, or it may be a microparticulate polymeric resin such as cross-linked polystyrene-divinylbenzene. The mobile phase is typically a binary mixture of a weak solvent, such as water or an aqueous buffer, and a strong solvent such as acetonitrile or a short-chain alcohol. Retention is modulated by changing the relative proportion of the weak and strong solvents. Additives may be incorporated into the mobile phase to modulate chromatographic selectivity, to suppress undesirable interactions of the analyte with the matrix, or to promote analyte solubility or stability. 

The production of polymers or bio-polymers which can be used as stationary phase or adsorbent, catalyst support, or as a matrix for drug impregnation. 

We now have a fairly adequate understanding of the different properties, including the particle diameter i/p, the pore size, the degree of permeability, and the chemical composition of the surface of the support matrix, to know which type of stationary phase can be successfully used with a particular class of peptides. Most of the HPLC packing materials now in use for peptide separations are based on the wide pore microparticulate silica gels with polar or nonpolar carbonaceous phases chemically bonded to the surface of the matrix. Methods for the preparation of these chemically bonded stationary phases, their available sources of supply. 

A stationary phase, where a solid, a gel or an immobilized liquid is held by a support matrix. 

This is based on the partitioning of a substance between two liquid phases, in this instance the stationary and mobile phases. Substances which are more soluble in the mobile phase will pass rapidly through the system while those which favour the stationary phase will be retarded (Fig. 31.2). In normal phase partition chromatography the stationary phase is a polar solvent, usually water, supported by a solid matrix (e.g. cellulose fibres in paper chromatography) and the mobile phase is an immiscible, non-polar organic solvent. For reversed-phase partition chromatography the stationary phase is... 

Tungsten was separated on DEAE-Sephadex for determination of trace amounts of alkali and alkaline-earth metals by AAS without matrix interference Dithi-zone in o-dichlorobenzene was used as the stationary phase on a Chromosorb support for the enrichment and separation of Zn,Cd,Hg and Cu By adding selective masking agents to the sample solution the adsorption of the traces was prevented the matrix was adsorbed. The separation of mercury from large amounts of copper on columns coated with silver dithizonate for example was reported. 

Supports for SEC of proteins are designed to be neutral and very hydrophilic to avoid disruption of protein structure and interaction of the solutes with the support by ionic or hydrophobic mechanisms. The base matrix can be either silica or polymer efforts are made to totally mask its properties with a carbohydratelike stationary phase. The pore structure is critical to successful SEC. Not only must the total pore volume (F,) be adequate for separation, the pore diameter must be consistent and nearly homogeneous for attainment of maximum resolution between molecules with relatively small differences in molecular size (radius of gyration or molecular weight). A twofold difference in size is usually required for separation by SEC. Pore homogeneity can be assessed from the slope of the calibration curve of the logarithm of the molecular weight versus the retention time or the partition coefficient (Kd) = (F - Fq)/F , where F is... 

The most convenient and most popular analytical methodology to assess enantiomer purity is the direct separation of enantiomers on so-called chiral stationary phases (CSPs). CSPs consist of an (ideally) inert chromatographic support matrix incorporating chemically or physically immobilized SO species. CSPs may be created by a variety of SO immobilization techniques, including (i) covalent attachment onto fhe surface of suitably pre-functionalized carrier materials, (ii) physical fixation employing coating techniques, and (iii) incorporation into polymeric networks by copolymerization, or combinations of these procedures. 

According to Ito, "CCC is governed by the same equations that apply to all forms of chromatography but, because the phase volumes are known in CCC, it is simple to express the equations in terms of the partition coefficient K = C/C where C represents solute concentration in the stationary phase, s, and mobile, m, phases, rather than the capacity factor k = K(V/VJ, where F represents the volume of the stationary, s, and mobile, m, phases. Because there is no supporting matrix, and the column volume, F (column) is known, the stationary phase volume can be obtained from... 

Notes The solid support of the stationary phase is known as the matrix, which includes cellulose, dextran, agarose, polyacrylamide, silica, polystyrene, polyvinyl, polyether and resins. The matrix of differing porosity and stability varies in the degree of cross-linkages. It is modified to confer specific properties the chemical attachment of various functional groups. 

---