Micellar exclusion chromatography

Micellar exclusion chromatography under equilibrium condi-ti ons. 

Size Exclusion Chromatography of Some Reversed Micellar Systems... 

The separation scientist with experience gained from a LC background may tend to limit the modes of electrochromatography to reversed phase (RP), normal phase, ion-exchange and, maybe, size-exclusion. Analysts from an electrophoretic background typically use the term "CE" in a much broader sense to include the main modes of capillary zone electrophoresis, micellar electrokinetic chromatography, capillary gel electrophoresis, isoelectric focusing and isotachophoresis. 

Liquid chromatographic analyses with ICP-MS detection may be divided into categories according to the mode of chromatography used reversed-phase, ion-pair, micellar, ion-exchange, and size-exclusion chromatography. 

For biorelevant dissolution media containing only bile salt and PL, dynamic light scattering determinations reveal that only one particle population in the micellar size range is present (Sunesen et al., 2005 llardia-Arana et al., 2006). Upon addition of free fatty acids and monoglycerides, the structure and size of the colloid phases in these media depend on absolute concentrations and the ratios between the amphiphiles. In general, a micellar fraction is still present but co-exists with particles of a vesicular size. This was also observed by Kossena and coworkers by the use of size exclusion chromatography (Kossena et al., 2003). 

S. Terabe, H. Tanaka, K. Otsuka and T. Ando, Separation of Small Molecules with Size Exclusion Chromatography Columns and Micellar Solutions, J Chromatogr. Sci., 27 653 (1989). 

T. Okada, Ion-exclusion Chromatography with Mixed Micellar Mobile Phases, Anal Chim. Acta, 230 9 (1990). 

Journal of Applied Polymer Science 61, No.8, 22nd Aug.1996, p.1325-31 DIRECT DETERMINATION OF THE RESIDUAL ACRYLAMIDE CONCENTRATION IN INVERSE (WATER-IN-OIL) POLYACRYLAMIDE EMULSIONS FOLLOWING PHASE INVERSION SIZE EXCLUSION CHROMATOGRAPHY USING A MICELLAR MOBILE PHASE Hemandez-Barajas J Hunkeler D J Petro M Vanderbilt University... 

The exclusion chromatography of surfactant solutions is a problematic method for analyses, since the micelles are only stable when in equilibrium with monomers of concentration equal to the cmc. The monomer-micelle equilibrium thus can be subjected to chromatographic investigations, under various conditions, e.g. dynamic or equilibrium. In the former case, if one applies a micellar solution with concentration greater than cmc, the surfactant front would move down the column at a speed relative to the size of micelles. However, if the dilution factor in the column is too large, such that only monomers are present, then the front moves at the same speed as the monomer. In these systems the eluant is supposed to be pure solvent. However, if concentration of the surfactant in the eluant is close to the cmc, then the micellar solution moves down the column with little perturbation of the monomer-micelle equilibrium. The surfactant front under these conditions then moves... 

This equilibrium will be perturbated in the chromatography of monomer-micelle systems because of dilution by the eluant (solvent). This process we shall designate as the "dynamic" analysis of micellar solutions by exclusion chromatography. 

In a recent study [51] the incorporation of alky1parabens into sodium lauryl sulfate (NaDDS) micelle and a change of the micellar structure was studied by various methods, among others by the elution volume of the micellar systems from the gel exclusion chromatography. Lauryl-paraben was used with methyl-, ethyl-, and butyl-parabens with a view to studying the effect of alkyl chain length on the solubilization. 

Francois and coworkers [137,138] reported on the synthesis of polystyrene-block-poly(p-phenylene) block copolymers via the anionic polymerization to poly styrene-block-poly (1,3-cyclohexadiene) and subsequent aromatization. The micellar assemblies and molecular dispersed free chains could be separated by size exclusion chromatography and with this method, the size of the spherical assemblies was found to be 30-50 A for the poly(p-phenylene) core, and 3-15 nm for the full micelle. By evaporating the solvent from solutions in carbon disulfide in moist air. 

Figure 24.12 compares the size-exclusion chromatography traces of the pentablock copolymer and the copolymer after it was irradiated at a final concentration of 2.0 mg/mL. We noticed the following features about the data. First, the peak maximum of the irradiated sample was shifted by 0.5 min toward the low molecular weight region. Secondly, no crosslinked micellar peak was observed for the irradiated sample despite the fact that the final polymer concentration was 2.0 mg/mL, which was 49 times greater than the cmc value (0.041 mg/mL) for the... 

High performance liquid chromatography Aqueous Normal Phase Chromatography Size exclusion chromatography Micellar liquid chromatography... 

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