Sorption size exclusion chromatography

Figure 13.2. Illustration of molecular separation according to their size in a size-exclusion chromatography (SEC) column. The underlying principle of SEC is that particles of different size will elute through a stationary phase at different rates Larger molecules will take less time (or elution volume) to reach outlet of the column as compared to the smaller ones.The prerequisite of a direct correlation between elution time and molecular size is an absence of interactions between the stationary phase and an analyte. Otherwise, nonexclusion effects such as electrostatic repulsion or sorption must be considered.

Size exclusion chromatography (SEC, also known as gel permeation chromatography) is a method of separating compounds of different molecular masses and sizes. Because steric interactions between analytes and the stationary phase are relatively weak, unstable forms of metals can be separated from more stable complexes and from adducts stabilized by ionic interactions. Unfortunately, the process of sorption and ionic interactions between the investigated substances and the stationary phase can decrease metal recovery by as much as 50 % these interactions are also responsible for the instability of retention times [146]. The separation can be performed both in the aqueous environment and in the presence of organic solvents. Because the technique is not selective, it is utilized primarily as the first stage of multidimensional chromatography [147]. 

Chromatography based on differences in the size of molecules is somewhat different from other forms of chromatography as there is no direct sorption between sample and stationary phase. Size exclusion chromatography (also known as gel permeation chromatography or gel filtration) is based around a... 

The last part of the book, Chapters 10—17, reports on different applications of polymers in the field of analytical chemistry sorption of organic compounds, Hke phenols, pesticides or caffeine, the use of polymeric materials for size-exclusion chromatography, for HPLC packing materials or as solid phase extraction sorbents. The examples cover a broad variety of chemical compounds, fike pesticides, pharmaceuticals, organic acids in different matrices, such as food, biological fluids, non-aqueous media, air and the use of hemosorbents in blood purification. 

Lubda, D., Lindner, W Quaglia, M., du Fresne von Hohenesche, C., Unger, K K., 2005. Comprehensive pore stmcture characterization of silica monohths with controlled mesopore size and macropore size by nitrogen sorption, mercury porosimetry, transmission electron microscopy and inverse size exclusion chromatography. J. Chromatography A 1083 14-22. 

Similar reactions form the basis of the separation of cations. An example of the separation of inorganic anions at the ppm level is shown in Figure 3(b). Size exclusion chromatography (SEC). This is suitable for mixtures of solutes with relative molecular masses (J(MM) in the range lOMO Da. Stationary phases are either microparticulate cross-linked co-polymers of styrene and divinyl benzene with a narrow distribution of pore sizes, or controlled-porosity silica gels, usually end-capped with a short alkyl chain reagent to prevent adsorptive interactions with solutes. Exclusion is not a true sorption mechanism because solutes do not interact with the stationary phase (Topic D2). They can be divided into three groups ... 

The chromatographic separation approach is often used to describe a method of running an IX column or an adsorption column. These are not considered here see Sections 4.13 and 4.11 and 4.12 respectively. Two uses of the chromatographic approach are considered here affinity or immunosorbent (that is similar to ad-sorption/IX but is usually applied to bioseparations) and size exclusion or gel chromatography, SEC. 

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