Size exclusion chromatography limitations

Conductivity detectors, commonly employed in ion chromatography, can be used to determine ionic materials at levels of parts per million (ppm) or parts per bUHon (ppb) in aqueous mobile phases. The infrared (ir) detector is one that may be used in either nonselective or selective detection. Its most common use has been as a detector in size-exclusion chromatography, although it is not limited to sec. The detector is limited to use in systems in which the mobile phase is transparent to the ir wavelength being monitored. It is possible to obtain complete spectra, much as in some gc-ir experiments, if the flow is not very high or can be stopped momentarily. 

An aqueous ethanol solution of acrylamide, 2,2 -methylenebisacrylamide as cross-linked agent and third acrylamide derivative, is dispersed in an n-alkane. Then three monomers are polymerized to spherical porous gels. The effect of the composition of the third monomer on the exclusion limits of the gel in size-exclusion chromatography has been investigated (82). 

The effect of temperature on column efficiency, however, is frequently exploited, particularly in size exclusion chromatography (SEC). As has already been discussed, high efficiencies are essential in SEC due to the limited peak capacity of the column and consequently, the very small separation ratios. However the effect of temperature on column efficiency is not well understood by many analysts and consequently, will be discussed in some detail. It was shown on page... 

M. De Nobili and Y. Chen, Size exclusion chromatography of humic substances limits, perspectives and prospectives. Soil Sci. 764 825 (1999). 

Purify the labeled protein by size exclusion chromatography using a column with an exclusion limit of molecular weight 5,000. 

To purify the conjugate from reactants that did get incorporated into the conjugate, size exclusion chromatography may be used with resins having a molecular exclusion limit able to accommodate both the labeled molecules and the final conjugate. 

The conformational mobility of a chromophoric main-chain polymer is often connected to its electronic structure. Therefore, changes in the UV-visible absorption spectra and/or chiroptical properties are spectroscopically observable as thermo-, solvato-, piezo-, or electrochromisms. It is widely reported that o-conjugating polysilanes exhibit these phenomena remarkably clearly.34 However, their structural origins were controversial until recently, since limited information was available on the correlation between the conformational properties of the main chain, electronic state, and (chir)optical characteristics. In 1996, we reported that in various polysilanes in tetrahydrofuran (THF) at 30°C, the main-chain peak intensity per silicon repeat unit, e (Si repeat unit)-1 dm3 cm-1, increases exponentially as the viscosity index, a, increases.41 Although conventional viscometric measurements often requires a wide range of low-dispersity molecular-weight polymer samples, a size exclusion chromatography (SEC) machine equipped with a viscometric detector can afford... 

Size-based analysis by CE provides similar information and comparable limits of detection to analysis by SDS-PAGE with Coomassie blue staining.120 129 The performance of both electrophoretic techniques for the analysis of polypeptides is far superior to size exclusion chromatography. Figure 9.7 shows the separation of SDS-complexed recombinant protein standards by CE. 

Two approaches are generally used to develop methods with lower detection and quantitation limits for target compounds. One approach involves the use of sample cleanup methods such as size exclusion chromatography (SEC) for the... 

Size exclusion chromatography. The concentrated hydrolyzate was applied to a Sephadex GIO column (78 x 1.8 cm, exclusion limit 700 Da) and elut-... 

Note For particles with molar mass or molecular weight larger than the exclusion limit the separation effect of the size-exclusion chromatography vanishes. 

A useful alternate to the Mayo plot for determining Cs (as well as other transfer constants) is the chain length distribution (CLD) method based on the molecular weight distributions obtained from size exclusion chromatography (SEC) [Christie and Gilbert, 1996, 1997 Heuts et al., 1998, 1999 Moad and Moad, 1996]. The limiting slope AHIGH of a... 

Size exclusion chromatography (SEC) separates molecules based on size in a short analysis time. Unlike other chromatographic techniques, SEC does not retain sample species in the column, the analysis time is fixed, and everything loaded onto the column elutes within a fixed time frame. The application of SEC is limited only to the solubility of the sample in a solvent. Since tetrahydrofuran (THE) is a good solvent for coal liquids, the separation of coal liquids by SEC can be easily achieved. 

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