Ratio, capacity separation

However, it must be emphasized that retention data, whether they be corrected retention volumes, capacity ratios or separation ratios, do not provide unambiguous solute identification. Matching retention data between a solute and a standard obtained from two columns employing different phase systems would be more significant. Even... 

The separation on the ODS-SDS column is achieved by the addition of a suitable complexing ligand to the mobile phase to discriminate between the various metal ions. The selectivity between two metal ions is achieved through two competing equilibria, namely the complexation equilibrium of the free metal ion in the micellar pseudo-phase and the complexation equilibrium of the metal ion adsorbed on the SDS mono-layer and this is shown in Fig. 1. It is evident from this equilibrium that the distribution ratio (capacity factor) of the metal ion is given by Eq. (1), where the subscripts a and represent the concentration of the free metal ion in the bulk aqueous phase and the adsorbed monolayer, respectively ... 

How does the separative capacity of a cross-flow gaseous diffusion stage vary with the cut At what cut is the separative capacity highest What is the ratio of separative capacity at a cut of I to the maximum separative capacity ... 

Graphs of Separation Ratio, Capacity Ratio and Minimum Column Length against... 

In order to optimize a separation and produce it in the minimum time, the capacity ratios and separation ratios must be measured for a given pair of enantiomers under known conditions of mobile phase composition and temperature (this will be discussed in detail later in this chapter). Unfortunately, when two peaks are eluted close together, which frequently occurs in chiral chromatography, the positions of the peak maxima are distorted due to the immediate presence of the other peak. An example of this problem is shown in figure 10.1, where the peaks are simulated and added, and the composite envelope plotted over the envelope of each individual peak. It is seen that the actual retention difference, if taken from the maxima of the envelope, will give a value of less than 60% of the true retention difference. Unfortunately, this type of error will probably not be taken into account by most data processing software. It follows, that if such data is used in an attempt to calculate the... 

Table 11.2 Capacity Ratios and Separation Ratios of Some Protected Alanine Derivatives Separated on Cellulose Columns...

Hollow fiber SL membranes allow faster analyte separation and higher enrichment factors compared to flat sheet membranes because of their high surface area to solvent volume ratios. Solvent volumes of the order of several microliters can be employed, which allows the coupling of hollow fiber SL membrane separation to other low sample capacity separation techniques (e.g., packed capillary liquid chromatography, capillary electrophoresis). 

In the mid-1980s, Ruhrchemie (now Hoechst) converted its oxo capacity to a proprietary water soluble rhodium catalyzed process (27,28), a technology developed jointly with Rhc ne-Poulenc. Product separation in this process is by decantation. Isomer ratios of n- to isobutyraldehyde of about 20 1 are obtained. 

The great utility of the separative capacity concept Hes in the fact that if the separative capacity of a single separation element can be deterrnined, perhaps from equations 7 or 10, then the total number of such identical elements required in an ideal cascade to perform a desired separation job is simply the ratio of the separative capacity of the cascade to that of the element. The concept of an ideal plant is useful because moderate departures from ideaUty do not appreciably affect the results. For example, if the upflow in a cascade is everywhere a factor of m times the ideal upflow, the actual total upflow... 

If the power requirement of the gaseous diffusion process were no greater than the power required to recompress the stage upflow from the pressure on the low-pressure side of the barrier to that on the high-pressure side, then the power requirement of the stage would be Z RTLq (1 /r) for the case where the compression is performed isotherm ally. The power requirement per unit of separative capacity would then be given simply by the ratio... 

The ratio method is also particularly useful for quick estimates over a range of capacities after a calculated estimate for one size has been made (10). The calculated estimate can be separated into groups C, C2,. .., according to individual equipment exponents n, n2,. Then an overall plant capacity exponent n can be calculated from... 

The thermal quality of the solvent feed has no effect on the value of (S/F)mjn, but does affect the minimum reflux to some extent, especially as the (S/F) ratio increases. R nax occurs at higher values of the reflux ratio as the upper-feed quality decreases a subcooled upper feed provides additional refluxing capacity and less external reflux is required for the same separation. It is also sometimes advantageous to introduce the primary feed to the extractive distillation column as a vapor to help maintain a higher solvent concentration on the feed tray and the trays immediately below... 

The sharpness of separation of the mineral from the gangue is dependent on (1) the stability of the suspension, which is influenced by the size of the medium (2) the specific gravity of the medium (3) the cleanliness of the medium (4) the cone angle (5) the size and ratios of the internal openings in the cyclone (inlet, apex, and vortex) and (6) the pressure at which the pulp is introduced into the cyclone. A 20° cone angle is the most common. Cyclone diameter will be determined by the separation to be made as well as by the capacity required. The 0.5- and 0.6-m (20- and 24-in) cyclones are most common in coal plants, whereas multiple cones of 0.25- or 0.3-m (10- or 12-in) diameter are used in higher-gravity separations. 

Equation (16) was first developed by Purnell [3] in 1959 and is extremely important. It can be used to calculate the efficiency required to separate a given pair of solutes from the capacity factor of the first eluted peak and their separation ratio. It is particularly important in the theory and practice of column design. In the particular derivation given here, the resolution is referenced to (Ra) the capacity ratio of the first... 

Figure 14. Graph of Log. Efficiency against Capacity factor for Solute Pairs having Different Separation Ratios...

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