Enantiomeric separation chiral pollutants

The temperature is a crucial parameter in optimization of the chiral resolution of environmental pollutants by GC, because the retention of the pollutant depends on the column temperature. Moreover, the formation of the diastereoisomeric complexes of the pollutants with the CSP also depends on column temperature. Therefore, a very slight variation in temperature may result in poor resolution and a loss of reproducibility. Also, variation of the temperature of the injector and the detector may change the selectivity, sensitivity and the reproducibility. Since the highest enantiomeric selectivity is achieved by maximizing the energy difference in the diastereoisomeric complexes formed between the pollutants and the CSP, these energy differences become smaller with increasing temperature. Therefore, to optimize chiral separation, a lower elution temperature... 

The eflBciency and ease of the chiral resolution of environmental pollutants depend on the type and stmcture of the chiral selector used in the GC column. Therefore, to achieve the best chiral separation it is important to select a suitable chiral selector. Basically, the chiral resolution of an environmental pollutant occurs due to the formation of a diastereoisomeric complex, and hence the selection of a suitable chiral selector that can form a stable diastereoisomeric complex is essential. As discussed earlier, various chiral selectors have been used for the enantiomeric resolution of environmental pollutants by GC and, among these, CDs and their derivatives have frequently been used. Various CDs and their derivatives used for chiral resolution are given in Table 6.2. Knowledge of the basic chemistry is helpful in selecting a suitable chiral selector for a specific pollutant. The chiral selector should be selected in a way that can provide the maximum number of bonding sites between the chiral selector and the... 

Cyclodextrin-based CSPs have been used for the chiral resolution of some pollutants. Schurig et al. [9, 10], Konig et al. [11] and Hardt etal.[ 2 used CD-based CSPs for the chiral separation of PCBs. Mannscreck etal. [13] resolved PCBs on triacetylcellulose CSP. Ludwig etal. [14] used the Chiral AGP column for the enantiomeric analysis of 2-(2,4-dichlorophenoxy)propionic acid (dichlorprop) and its degradation products in a marine microbial community. The authors used a... 

Chirobiotic T. The authors achieved chiral separation of these pesticides using methanol as the major constituent of the mobile phase, with detection by a diode array detector. The chiral resolution of some environmental pollutants by HLPC is given in Table 7.2. As a specific example, the chromatograms of the resolved enantiomers of crufomate and a-HCH are shown in Figure 7.2. As usual, the enantiomeric resolution is expressed by... 

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