Enhancement of separation

Both the fundamental and the technical difRculties, whtdh are usso-ciiiiril with the use of these programming techniques, increase in the above order. However, the enhancement of separation capability and the range of applications also increase in the same order. 

The most important point to be noted is that as is not limited by the ratio K2/K1 and can reach infinitily high values in CE (3,4). Although Eq. (2) does not explicitly contain the binding constants of enantiomers with chiral selector, A/x and /xav are dependent on these thermodynamic quantities. Capillary electrophoresis offers several possibilities for almost unlimited enhancement of separation selectivity without any significant change of thermodynamic selectivity or recognition (3-5). 

Enhancement of Separation. For some applications, a single column cannot adequately perform the complete separation of all the desired components. By connecting a second column and detector system in series with the normal one, components not resolved on the first column can be selectively switched into the second column for further separation and then detected on the second detector. If the columns are of the same liquid phase, shorter... 

Khaledi, M. G., J. K. Strasters, A. H. Rodgers, and E. D. Breyer. 1990. Simultaneous enhancement of separation selectivity and solvent strength in reversed-phase liquid chromatography using micelles in hydro-organic solvents nal. Chem62 130-136. 

One of the current researches devoted to membrane treatment of radioactive waste is directed toward seeded ultrafiltration and all methods, which combined with ultrafiltration, give considerable enhancement of separation (Table 30.6). 

The number of theoretical plates and, thus, the separation efficiency, is determined by the length of the separator column. If two separator columns are used in series, the resulting enhancement of separation efficiency leads to a better resolution between ions with similar retention characteristics, with a corresponding increase in retention times. The separator column length also determines the exchange capacity. An increase of the exchange capacity via elongation of the separator column is recommended in all cases where the ion to be analyzed is present in an excess of another component. 

Examples of using cyclodextrin modifiers for enhancement of separation has been shown by Baeyens, et al.[44] and Yeo, et al. [45]. The first group demonstrated the separation of pilocarpine and isopilocarpine in ophthalmic preparations, while the later demonstrated the separation of plant growth hormones. 

Atypical laboratory bottle test is indicated in Fig 24 and 25, which illustrate the separations of a model 30% W/O bitumen (Athabasca, Alberta) emulsion at 50°C with two demulsifiers, A and B. In Fig. 24 (top photograph) the emulsion was allowed to resolve over 24 h by gravity. This is compared with the bottom photograph whieh shows the same treated emulsion assisted in separation by eentrifuga-tion immediately after demulsifier addition. The differenee illustrates that enhancement of separation with a proeess aid sueh as centrifugation is useful for this system if time is a faetor. The demulsifiers are eonsidered to be effectively... 

M.G. Khaledi, J.K. Strasters, A.H. Rodgers and E.D. Breyer, Simultaneous Enhancement of Separation Selectivity and Solvent Strength in RPLC using Micelles in Hydro-Organic Solvents, Anal. Chem., 62 130 (1990). 

Typical uses Enhancement of separation rates in otherwise more conventional equipment. 

A.K. Agarwal and R.Y.M. Huang, Studies on the Enhancement of Separation Characteristics of Sulfonated Poly (Phenylene oxide)/PolysuIfone Thin Film Composite Membranes for Reverse Osmosis Applications II. Effects of Nitromethane and the Chemical Treatment Combined with Gamma-Ray Irradiation, Angewandte Makromol. Chem., 1988,163, 15-21. 

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