Separation optimization choices related

The selectivity triangle with numerous solvents is discussed in Section 5.2. Eluent selectivity in reversed-phase separations is directly related to this triangle because localization effects, important in adsorption chromatography, play no role. A look at Figure 5.1 shows that the three solvents methanol, acetonitrile and tetrahydrofuran are a good choice for the optimization of selectivity. Figure 10.4 represents a triangle with these three solvents only. 

Carbon-based catalysts and in particular their kinetics have been intensively studied [41 3], because they should reduce the disadvantages related to metal-based catalysts. Carbon materials are more available, have the potential of cost reduction, do not require periodic regeneration because it is not necessary to separate the carbon-product from the catalyst. The fluidised bed reactor technology represents the optimal choice for this kind of hydrocarbon cracking process as it can withdraw the carbon particles evermore, permitting a reliable storage of produced carbon for further use [44 46]. A novel technological solution aimed to improve activity and stability of carbon catalysts has been recently proposed [47]. The presence of small amount of O2 in an autothermal approach seems to be the best solution to minimize CO2 emissions in the overall process. 

In general, LC peak capacity can be reduced if it is counter-balanced by an increased MS peak capacity in the orthogonal mass domain. Increasing the dimensions in LC/MS separations is another option to increase overall peak capacity in a given time, but comes at a cost of increased complexity of instruments and data evaluation. In the mass domain, highly resolving mass spectrometers round out the choices. Nevertheless, every throughput optimization step should be viewed in relation to... 

Optimization of operating conditions is also made with reference to the final target The choice of whether to pressurize the feed stream or to use vacuum or a sweep gas on the permeate side, depends on assodated costs and on the specific case considered. For example, if the feed stream is already available in the plant at the pressure needed, the permeate can operate at atmospheric pressure. Otherwise, the energy required to apply vacuum or to pressurize the feed must be compared to the costs of the sweep gas as well as the costs related to the additional separation of the diluted permeate. 

The development of a theory of retention and band broadening for macro-molecular HPLC is intended primarily for improving such separations. We need to relate various separation goals to (1) experimental conditions, (2) the choice of column type and HPLC method (RPLC, SEC, etc.), and (3) the nature of the sample. The present model allows os to do this 1 prediction, rathor than by experiment Our main requirement is usuaOy to achieve adequate separation, or some minimum resolution R, betw adjacent bands of interest. In this section we will show that the separation of macro-molecular samples by either isocratic or gradient elution is understandable and controllable, using the same concepts that we use for optimizing the isocratic separation of small molecules. 

The main task of analytical TLC is separation of sample from matrix, separation of sample components, their identification, and the measurement of peak heights or areas for quantitative purposes. Finally, the peaks should be narrow and symmetrical. Two problems are related to the analysis choice of suitable conditions of development, such that all components of the sample are eluted in optimal range of retention factor and their separation, allowing for identification and quantitation. 

In ideal SEC, no interactions between the sample and the support should occur only the pore dimension and the pore size distribution and therefore the volumes related to the porosity and to the interparticle volume can influence the separation. This makes SEC an easy and quick method to handle and to optimize in comparison with other chromatographic techniques such as ion-exchange chromatography or reversed-phase chromatography. Analyses of proteins in SEC are in fact carried out in the isocratic mode and the choice of the mobile phase is only directed to minimize the interactions between the sample and the support surface it does not influence the retention of the analyte when ideal conditions... 

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