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National Repository of Grey Literature 2 records found  Search took 0.02 seconds. 
Preparation of new chiral phases for HPLC anchored to silica gel using electrostatic interactions
 Tomanová, Adéla ; Jindřich, Jindřich (advisor) ; Smrček, Stanislav (referee)
The focus of this thesis is the synthesis of chiral modifiers for silica gel based on amylose modified with dimethyl or dichlorophenyl isocyanates and positively charged anchors, which will allow strong ionic binding to silica gel. The stability of the stationary phases thus prepared is then studied by liquid chromatography as well as the ability to separate selected enantiomers. Two chiral silica gel modifiers were prepared in which the amylose contained dimethyl phenyl carbamate (DMFKA) or dichlorophenyl carbamate (DCFKA) groups in addition to the covalently bonded anchor. The results of elemental analysis showed incomplete modification of the hydroxyl groups of the second modifier, DCFKA, which also corresponded to the poor chromatographic results obtained on columns packed with this phase. Enantioselective separations of α-(1-naphthyl)benzylamine, fenamiphos and a number of chiral adamantane derivatives were achieved on columns packed with DMFKA phase. The possibility of modifying silica gel in an already packed HPLC column with a modifier from solution was also demonstrated by pumping this solution through a silica gel packed column and subsequent washing into the mobile phase. Keywords: chiral separation, electrostatic interaction, HPLC
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Chiral membrane prepared by electrostatic modification of ionexchange membrane
 Čížek, Jan
In this work, a simple and effective method for chiral membrane preparation is demonstrated, involving electrostatic interaction between negatively charged sulfobutylether-β-cyclodextrin (SBE-β-CD) as a chiral selector and a commercially available anionexchange membrane.The modified home-made chiral membrane was tested in diffusion cells to characterize its enantioselectivity towards D,L–Tryptophan. We demonstrated in our work that L–Tryptophan is preferentially absorbed into the membrane, while D–Tryptophan\nis transported through the membrane with enantiomeric excess exceeding 80%. To increase the permeation rate of the membrane, thinner ion-exchange membrane substrate with higher degree of swelling is proposed.\n
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