Theoretical plate height reduced

These axial temperature gradient-induced pressure-driven flows can cause hydrodynamic dispersion (see Eq. 33) and thus reduce the separation efficiency. The latter is usually evaluated in terms of the theoretical plate height H... 

FIGURE 22.9 Reduced plate height versus reduced velocity. Measured data V, toluene O, PS 2200 , PS 43,900 A, PS 77S.000. Theoretical lines solid lines, Giddings, infinite diameter column dotted line, Knox, infinite diameter column dashed line Knox walled column. (Reprinted from J. Chromatogr., 634, IS4, Copyright 1993, with permission from Elsevier Science.)... 

The reduced plate height, h, is defined as the number of particles to a theoretical plate and is given by... 

Golay equation 21, 611 gradient (LC) 490 height equivalent to a theoretical plate 11 longitudinal diffusion 16 mass transfer resistance 17 nonlinear chromatography SOS plate model 14 rate theory IS reduced parameters 78, 361, 611... 

The van Deemter plots in Figure 25-3 show that small particles reduce plate height and that plate height is not very sensitive to increased flow rate when the particles are small. At the optimum flow rate (the minimum in Figure 25-3). the number of theoretical plates in a column of length L (cm) is approximately3... 

Height equivalent to a theoretical plate. h h (reduced plate height). The number obtained by dividing the column length by the theoretical plate number. 

The efficiency of chromatographic systems can be defined by the height equivalent to a theoretical plate (HETP or plate height, symbol H) or by the reduced plate height ... 

The resolution factor is considered to be a more discriminating measure of system suitability than column efficiency [44]. Yet, column efficiency determinations are required for the assay of antibiotics and antibiotic-containing drugs [53]. The reduced plate height (hr) for the column is determined by first calculating the number of theoretical plates per column ... 

The most commonly used criterion for judging column performance is efficiency as measured by the number of theoretical plates or column plate count (N) exhibited by the column during the separation of a test mixture. The larger the number of theoretical plates, the more likely it is that the column will produce the desired separations. However, while popular, N is not a complete performance parameter for making comparisons. For example, N does not take into account particle size as does the reduced plate height, h. Another measurement, hmin, accounts for all of these factors as well as the mobile phase linear velocity and sample diffusion. However, N is the term most commonly recognized as being related to resolution (2), as shown in Equation 1 ... 

If the required number of plates is moderate (say several thousands), then short capillary columns may be used to provide fast analysis of the sample. The required column length and retention time can easily be calculated from eqns.(7.3) and (7.6). For example, if we operate a capillary column with a diameter of 200 pm at a reduced velocity of 5 with a reduced plate height of 1.5, then 2000 theoretical plates require a column with... 

Since the retention of the template on the imprinted polymers strongly depends on the sample load (see later Fig. 5.25), the theoretical models describing the various dispersion processes are not applicable. Nevertheless, on an imprinted CSP for L-PA, the least retained enantiomer, D-PA, elutes as a fairly Gaussian peak (Fig. 5.3), which should be governed by the same band broadening mechanisms that are considered in the models. A measure of the dispersion of a Gaussian peak is the deviation from its mean value, which is reflected in the reduced plate height as ... 

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