Chromatography frontal

Fritting From squalene Frontal Frontal chromatography Frontalin [28401-39-0] Froth Froth ers... 

Development of the Chromatogram. The term development describes the process of performing a chromatographic separation. There are several ways in which separation may be made to occur, eg, frontal, displacement, and elution chromatography. Frontal chromatography uses a large quantity of sample and is usually unsuited to analytical procedures. In displacement and elution chromatography, much smaller amounts of material are used. 

The competitive adsorption isotherms were determined experimentally for the separation of chiral epoxide enantiomers at 25 °C by the adsorption-desorption method [37]. A mass balance allows the knowledge of the concentration of each component retained in the particle, q, in equilibrium with the feed concentration, < In fact includes both the adsorbed phase concentration and the concentration in the fluid inside pores. This overall retained concentration is used to be consistent with the models presented for the SMB simulations based on homogeneous particles. The bed porosity was taken as = 0.4 since the total porosity was measured as Ej = 0.67 and the particle porosity of microcrystalline cellulose triacetate is p = 0.45 [38]. This procedure provides one point of the adsorption isotherm for each component (Cp q. The determination of the complete isotherm will require a set of experiments using different feed concentrations. To support the measured isotherms, a dynamic method of frontal chromatography is implemented based on the analysis of the response curves to a step change in feed concentration (adsorption) followed by the desorption of the column with pure eluent. It is well known that often the selectivity factor decreases with the increase of the concentration of chiral species and therefore the linear -i- Langmuir competitive isotherm was used ... 

A relatively large volume of sample can be applied to the wet layer from the edge of the layer from the eluent distributor, forming a partly separated starting band by the frontal chromatography stage. 

A Lundqvist, E Brekkan, L Haneskog, Q Yang, J Miyake, P Lundahl. Determination of transmembrane protein affinities for solutes by frontal chromatography. In P Lundahl, A Lundqvist, E Greijer, eds. Quantitative Analysis of Biospecific Interactions. Amsterdam Harwood Academic, 1998, pp 79-93. 

Frontal chromatography. A chromatographic separation in which the sample is fed continuously into the column. 

In principle, the experimental protocol of fluidized bed adsorption does not deviate from packed bed operations, the main difference being the direction of liquid flow. The standard sequence of frontal chromatography, equilibration, sample application, wash, elution, and cleaning (CIP) is performed with an upward direction of flow as shown in Fig. 3. During equilibration of the matrix the stabilization of the fluidized bed occurs, in case of size and/or density distribution of the adsorbent particles the classification within the bed may be detected by visual observation of the bed. As discussed below, bed stability may... 

Figure 2.44. Comparison of (a) elution development and (b) frontal chromatography.

The use of N2O to determine Cu surface areas requires great care to avoid subsurface oxidation. The frontal chromatography method, in which a dilute mixture of N2O and He (typically, 2% N2O) is passed over a large bed of catalyst until no further N2O is reacted, appears to be the most reliable method. In the pulse method the extent of subsurface oxidation depends on the temperature (a very serious problem above about 100 °C), the size of the N2O pulse, the size of the catalyst sample, the metal loading of the sample, and the geometry of the catalyst bed. In general, small pulses of N2O should be used, at temperatures below about 60 °C, with a deep catalyst bed (>1 cm). 

When comparing the intrinsic methanol synthesis activity of both catalysts (turnover frequency [TOF] per surface Cu site measured with N20-reactive frontal chromatography) at the space velocity of 20 mmol/gcatmin, the HT catalyst (0.54 min-1) appears twice as active as the MA catalyst (0.24 min-1). Although both catalysts are exposed to nearly the same reactant concentration, the MA catalyst operates at 11% CO2... 

Chinchen GC, et al. The measurement of copper surface-areas by reactive frontal chromatography. J Catal. 1987 103(1) 79—86. 

The adsorption isotherms are measured via the frontal chromatography method. Because the interaction between the products was expected to be weak, both products were simultaneously present in the injected feed. 

TABLE 4 Frontal Chromatography Experimental Breakthrough Curves in Grams Per Liter Obtained for the Mixtures of Mono- and Disaccharides of Different Concentrations... 

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