Mobile phase studies using polymeric

Thirty-one extremely large PAHs (from pyrene with four fused rings to tetra-benzo[a,ct/,///w]perylene with nine fused rings) were studied using a polymeric C,g column (photodiode array detector, A = 250-600 nm). Methanol/dichloromethane mobile phases were used to solubilize and elute these compounds [157]. Plots for... 

In 1978, Harada et al. [17] used polymerized CD with gel support for the chiral resolution of mandelic acid and its derivatives. Later Zsadon et al. [18-21] used cyclodextrin-based CSPs for the chiral resolution of indole alkaloids, with aqueous buffers as the mobile phases. Today CD-based CSPs have a good reputation. In separate studies, Fujimura [22] and Kawaguchi [23] and their colleagues resolved the enantiomers of aromatic compounds in the reversed-phase mode. Armstrong et al. [29,30,33,34,41,44 46,48,54-63] carried out extensive and remarkable work on the chiral resolution of various racemic compounds using CD-based CSPs. 

The first type of HPLC column investigated was a polymeric octadecylsilane column. A number of different mobile phase systems were examined as shown in Table VI For these isocratic studies a flow rate of 40 ml/hr and 100 ng of VI in mobile phase as the analyte was used. 

Temperature affects the separation of fullerenes quite dramatically when monomeric or polymeric C g phases are used. With hexane as mobile phase (A = 312 nm), the chromatographic changes due to temperatures ranging horn 20°C down to -70 C were studied [654]. Increased resolution of C76 to Cg4 fullerenes was obtained as the temperature was decreased from 20°C down to —20°C. Below this temperature, all resolution was completely lost regardless of the monomeric or polymeric nature of the Cig phase. The authors speculate that the bonded phase becomes rigid or frozen at temperatures below —20°C, which precluded effective interaction wife the solutes. The compatibility of alkanes with very low-temperature work is rarely utilized and could be advantageous for many other separations. 

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