Resolution efficiency

Detector Resolution Efficiency Maximum count rate in single-pulse technique (kHz)... 

Time resolution efficiency coefficient (R, time resolving power, see Eq. (9.33), it time resolution needed)... 

The order of elution is governed by the length of the fatty acid carbon chain and the number of double bonds in it. These opposing tendencies lead to the occurrence of several pairs of fatty acids that are difficult to separate and the separation of which may be considered a criterion of the resolution efficiency of an analytical procedure. 

Separation speed and ease of use seem to be the primary factors driving changes in HPLC instrumentation. Resolution efficiency and stationary phase stability, especially at high pH, are the primary factors affecting current changes in column technology. 

Efficiency of the chromatographic system can be determined from the number of theoretical plates per meter. Although this term primarily describes the property and resolution efficiency of a column, other extra column variables, such as the... 

In order to easily compare the resolution results, we defined the resolution efficiency ( ) as 1/100 value of the product of the theoretical yield (a half amount of the racemate is assumed to be 100 %) and the optical purity (O.P., % ee) of the resulted enantiomer or ... 

Resolving agent Solvent Yield [%] Optical purity [%ee] Resolution efficiency E... 

Theoretically, the procedure shown in Figure 14 can be effective for all of the combinations of preferentially resolvable less-soluble diastereomeric salts. However, practical activity of optically active material gradually decreases since resolution efficiency is not 100% in every process. In fact, yields of reciprocal resolution of ( )-phenylglycine (PG) and ( )-10-camphorsulfonic acid (CSA) gradually decreases as shown in Table 7. 

Suzuki et al. [819] studied the determination of chlorinated insecticides in river and surface waters using high resolution electron capture gas chromatography with glass capillary columns. They compared resolution efficiencies of organochlorine insecticides and their related compounds with wall-coated open tubular (WCOT) and support-coated open tubular (SCOT) glass capillary columns with those of conventional... 

We tested this procedure on 10 different known resolutions, some of which were run on large scale. However, in only three cases was a clear result obtained in line with the known resolution efficiency. For all other examples no workable DSC thermogram was obtained. Phase transitions, loss of solvates... 

Other examples of application of this concept are presented in Table 7.2. It should be mentioned that the resolutions described in Table 7.2 intentionally are performed in nonoptimized conditions. Therefore, further improvement of the resolution efficiency should be possible when nucleation inhibitors are applied. The procedure clearly offers the opportunity to improve the outcome of a classical resolution without the need for stoichiometric mixtures of resolving agents. The original DR procedure as well as molecular modeling calculations32 can help in identifying efficient nucleation inhibitors. 

Wilson RM, Jen WS, MacMillan DWC (2005) Enantioselective organocatalytic intramolecular Diels-Alder reactions. The asymmetric synthesis of solana-pyrone D. J Am Chem Soc 127 11616-11617 Xie JH, Zhou ZT, Kong WL, Zhou QL (2007) Ru-catalyzed asymmetric hydrogenation of racemic aldehydes via dynamic kinetic resolution efficient synthesis of optically active primary alcohols. J Am Chem Soc 129 1868-1869... 

Compared to HPLC, GC, TLC, GLC, and IC, CE offers (1) high resolution efficiency, (2) rapid separation speed, (3) simple sample pretreatment, (4) small consuming sample, and (5) short analysis time. No derivatiza-tion is needed as in GC or a sample extraction as in HPLC or IC. Addition of SDS (anionic surfactant) causes an increase in migration times of all organic acids. (Tang and Wu, 2007). 

Amine (R-) Yield (%) Enantiomeric excess(%) Resolution efficiency... 

Yield is based on a half amount of the racemate. Enantiomeric excess is ofthe recovered amine. Resolution efficiency = yield x e.e. 

Fig. 5.8 Relation between the resolution efficiency and the relative molecular...

On the other hand, in the cases with low resolution efficiencies, both diastereo-... 

Table 5.4 I mprovement of resolution efficiency upon introduction of a substituent at the p-position of mandelic acid.

As shown in Table 5.4, the resolution efficiencies for the p-substituted 1-phenyl-efhylamine derivatives were greatly improved, as was expected, when p-methyl-and p-methoxymandelic acids were used in the place of mandelic acid. These results strongly support our explanation that two factors, hydrogen-bonding interaction to form a supramolecular sheet consisting of 2i-columns and van der Waals interaction between the sheets, govern the stability of diastereomeric salts [11]. The same factors were also found in the diastereomeric salts of racemic arylalka-noic acids with enantiopure amino alcohols [12]. 

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