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Chromatography Gaussian solution

Distribution Coefficients. Gel-permeation stationary-phase chromatography normally exhibits symmetrical (Gaussian) peaks because the partitioning of the solute between mobile and stationary phases is linear. Criteria more sophisticated than those represented in Figure 8 are seldom used (34). [Pg.51]

The profile of the concentration of a solute in both the mobile and stationary phases is Gaussian in form and this will be shown to be true when dealing later with basic chromatography column theory. Thus, the flow of mobile phase will slightly displace the concentration profile of the solute in the mobile phase relative to that in the stationary phase the displacement depicted in figure 1 is grossly exaggerated to demonstrate this effect. It is seen that, as a result of this displacement, the concentration of solute in the mobile phase at the front of the peak exceeds the equilibrium concentration with respect to that in the stationary phase. It follows that there is a net transfer of solute from the mobile phase in the front part of the peak to the... [Pg.6]

The area of a peak is the integration of the peak height (concentration) with respect to time (volume flow of mobile phase) and thus is proportional to the total mass of solute eluted. Measurement of peak area accommodates peak asymmetry and even peak tailing without compromising the simple relationship between peak area and mass. Consequently, peak area measurements give more accurate results under conditions where the chromatography is not perfect and the peak profiles not truly Gaussian or Poisson. [Pg.266]

Since the concentration profile of a solute in the effluent from a chromatography column can be approximated by the Gaussian error curve, the peak width W (m ) can be obtained by extending tangents at inflection points of the elution curve to the base line and is given by... [Pg.178]

A chromatography column of 10 mm i.d. and 100 mm height was packed with particles for gel chromatography. The interparticle void fraction e was 0.20. A small amount of a protein solution was applied to the column and elution performed in an isocratic manner with a mobile phase at a flow rate of 0.5 cm min. The distribution coefficient A of a protein was 0.7. An elution curve of the Gaussian type was obtained, and the peak width W was 1.30 cm . Calculate the Hs value of this column for this protein sample. [Pg.180]

A band of solute broadens as it moves through a chromatography column. Ideally, an infinitely narrow band applied to the inlet of the column emerges with a Gaussian shape at the outlet (Figure 23-11). In less ideal circumstances, the band becomes asymmetric. [Pg.513]

The separation of compounds by their differential partition between two immiscible phases is the basis for partition chromatography. The system consists of a stationary liquid phase coated on an inert solid support, and an immiscible mobile phase. Chromatographic separations are based on the different equilibrium distributions of the samples between these two phases. The greater the quantity of substance in the stationary phase at equilibrium the dower is the migration. For analyses, this equilibrium must remain constant over a suitable concentration range. Thus an increase in the concentration of solute results in a linear increase in the concentration of solute in the mobile and stationary phase, respectively. Under these conditions, the retention time, tR, is independent of the amount of sample chromatographed and a symmetrical peak (gaussian band) is observed. [Pg.8]

Factors leading to non-Gaussian zones in separation systems were described generally in Section 5.9. One source of zone asymmetry identified was the variation of local solute velocity W with solute concentration, described as overloading. The way in which overloading causes zone asymmetry in chromatography is explained below. [Pg.236]

Driven by the concentration gradient, solutes naturally diffuse when contained in a fluid. Thus, a discrete solute band will diffuse in a gas or liquid, and because the diffusion process is random, it will produce a concentration curve that is Gaussian in form. This diffusion effect occurs in the mobile phase of both packed GC and liquid chromatography (LC) columns. The longer the solute band remains in the column, the greater will... [Pg.1334]

Using the results of Lapidus and Amundson [3], Van Deemter et al. [4] demonstrated that a simplification of considerable importance can be made to the solution derived by these authors if we assume that the mass transfer kinetics is not very slow, which is almost always the case in analytical or preparative applications of chromatography. Then, Eqs. 6.46 and 6.47 can be reduced to a Gaussian profile ... [Pg.299]

Figure 6.6 Comparison of the chromatogram given by the film mass transfer-pore diffusion model of chromatography with a Gaussian Profile. Dimensionless plot of versus f. Solid line Gaussian profile. Dotted line Carta s solution [34]. (a) Nap = N = 25 theoretical plates, (b) Nap = N = 100. Reprinted by permission of Kluwer Academic Publishing, from S. Golshan-Shirazi and G. Guiochon, NATO ASI Series C, vol 383, 61 (Fig. 4), with kind permission of Springer Science and Business Media. Figure 6.6 Comparison of the chromatogram given by the film mass transfer-pore diffusion model of chromatography with a Gaussian Profile. Dimensionless plot of versus f. Solid line Gaussian profile. Dotted line Carta s solution [34]. (a) Nap = N = 25 theoretical plates, (b) Nap = N = 100. Reprinted by permission of Kluwer Academic Publishing, from S. Golshan-Shirazi and G. Guiochon, NATO ASI Series C, vol 383, 61 (Fig. 4), with kind permission of Springer Science and Business Media.
In most cases, chromatography is performed with a simple initial condition, C(f = 0,z) = q t = 0,z) = 0. TTie column is empty of solute and the stationary and mobile phases are under equilibrium. There are some cases, however, in which pulses of solute are injected on top of a concentration plateau (see Chapter 3, Section 3.5.4). The behavior of positive concentration pulses injected xmder such conditions is similar to that of the same pulses injected in a column empty of solute and they exhibit similar profiles. Even imder nonlinear conditions (high plateau concentration), a pulse that is sufficiently small can exhibit a quasi-linear behavior and give a Gaussian elution profile. Its retention time is linearly related to the slope of the isotherm at the plateau concentration. Measuring this slope is the purpose of the pulse method of measurement of isotherm data. Large pulses may also be injected and they will give overloaded elution profiles similar to those obtained with a column empty of solute. [Pg.368]

Isotherms plot of distribution ratios K, that is, a plot of concentration of the component in the stationary phase versus concentration in the mobile phase. Isotherms represent the relative attraction of a solute for the stationary and mobile phases, the plot is linear for a symmetrical Gaussian peak, non linear isotherms lead to unsymmetrical peaks, e.g. peak fronting and tailing. Langmuir isotherms describe the equilibrium process in adsorption chromatography, Nernst isotherms relate to partition chromatography. [Pg.534]


See other pages where Chromatography Gaussian solution is mentioned: [Pg.474]    [Pg.509]    [Pg.520]    [Pg.866]    [Pg.511]    [Pg.703]    [Pg.144]    [Pg.6]    [Pg.100]    [Pg.163]    [Pg.13]    [Pg.90]    [Pg.228]    [Pg.452]    [Pg.482]    [Pg.299]    [Pg.562]    [Pg.315]    [Pg.55]    [Pg.284]    [Pg.289]    [Pg.305]    [Pg.627]    [Pg.268]    [Pg.270]    [Pg.128]    [Pg.198]    [Pg.21]    [Pg.26]    [Pg.49]    [Pg.318]    [Pg.32]   
See also in sourсe #XX -- [ Pg.882 , Pg.883 , Pg.884 , Pg.885 ]




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Chromatography Gaussian

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