Chromatography curves

Overall, the most effective factor in Equation 5.20 is the particle size. The smaller the particle size, the higher the column efficiency. Equations 5.13, 5.15, and 5.18 are depicted in Figure 5.6 against flow velocity as A, B, and C, respectively. The band spreading is thus influenced by Equation 5.15 at a low flow rate. The band spreading is influenced by Equations 5.18 and 5.19 at a high flow rate. For gas chromatography curve D is obtained. 

Methyl methacrylate polymerizations, initiated by oiganomagnesium compounds, also yield abnormal products. Here, the active centers are unusually persistent and stabile. In addition, the a-carbon atoms of the monomers were found to assume tetrahedral configurations.This suggests that the active centers contain covalent magnesium carbon bonds. Also, gel permeation chromatography curves of the products show that more than one active center operates independently. A pseudoanionic mechanism was therefore postulated for polymerizations of acrylic and methacrylic esters by Grignard reagents. 

Size exclusion chromatography curves of pure PEs (straight line), and PE/D72T nanocomposites obtained with precatalyst A route 1 (dashed line), route 2 (dashed-dotted line) (a), with precatalyst B route 1 (dashed line), route 2 (dashed-dotted line) (b). (Adapted from Leone, G. et al, /. Polym. Sci., Part A Polym. Chem., 47,548,2009.)... 

Figure 6 A typical gel permeation chromatography curve for PP showing molecular weight distribution...

Distillation simulated by gas chromatography is a reproducible method for analyzing a petroleum cut it is appiicabie for mixtures whose end point is less than 500°C and the boiling range is greater than 50°C. The results of this test are presented in the form of a curve showing temperature as a function of the weight per cent distilled equivalent to an atmospheric TBP. 

Calibration curve for the determination of formula weight by size-exclusion chromatography. 

Fig. 3. Molecular weight distribution curves as determined by gel-permeation chromatography. A represents i9f2v (9-phthahc resins B, highest molecular...

Impurities in hydrocarbons can be characterised and evaluated by gas chromatography and mass spectrometry. The total amount of impurities present can be estimated from the thermometric freezing curve. 

Gaussian curve and, thus, also has significance when dealing with chromatography theory. 

An interesting and practical example of the use of thermodynamic analysis is to explain and predict certain features that arise in the application of chromatography to chiral separations. The separation of enantiomers is achieved by making one or both phases chirally active so that different enantiomers will interact slightly differently with the one or both phases. In practice, it is usual to make the stationary phase comprise one specific isomer so that it offers specific selectivity to one enantiomer of the chiral solute pair. The basis of the selectivity is thought to be spatial, in that one enantiomer can approach the stationary phase closer than the other. If there is no chiral selectivity in the stationary phase, both enantiomers (being chemically identical) will coelute and will provide identical log(Vr ) against 1/T curve. If, however, one... 

FIGURE 1.5 Cumulative pore volume curves of 5-/j.m monosized porous particles. [Reprinted from T. Ellingsen et al. (1990). Monosized stationary phases for chromatography. J. Chromatogr. 535, 147-161 with kind permission from Elsevier Science-NL, Amsterdam, The Netherlands.]... 

The HdC calibration curves of different particle sizes, as shown in Fig. 22.12 (30), are similar to the calibration curves of different pore size columns the separation ranges of MW due to hydrodynamic chromatography depend on particle size. The larger the particle size, the higher the MW ranges. Stegeman et al. (30) proposed that a smooth calibration curve may be achieved by proper ratio of the particle diameter to the pore diameter. 

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 ... 

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