Enantioselective capillary electrophoretic separation of tryptophane- and tyrosine-methylesters in a dual system with a tetra-oxadiaza-crown-ether derivative and a cyclodextrin

Chiral Separations by Capillary Electrophoresis

“…Three consecutive papers [88][89][90] covered the use of self-synthesized crown ethers and tested their potential as chiral selector in CE. Two diaza crown ether derivatives were synthesized and tested by means of five amino acid derivatives: tryptophan, tryptophan butyl ester, tryptophan ethyl ester, tyrosine methyl ester, and tryptophan butyl ester [88].…”

“…Next, an experimental design approach was used to study the influence of the concentration of the racemic diaza crown ether, the concentration of either M-β-CD or DM-β-CD, and the buffer concentration on the separation of tryptophan methyl ester and tryptophan ethyl ester [89]. In general, the newly synthesized crown ether had a positive influence on the selectivity, but migration times also increased using the dual systems.…”

Advances in chiral separation using capillary electromigration techniques

“…The authors observed an improvement in selectivity by addition of ACN and tetrabutyl ammonium bromide (TBAB). Dual selector systems containing a new crown ether derivative, N- [2-(1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7-yl)propanoyl]-glycine and a CD derivative were investigated by vander Heyden and coworkers [58]. The authors found that without CDs the crown ether showed no or only poor chiral separation ability using tryptophan methylester and tyrosine methylester as model compounds.…”

Recent advances in amino acid analysis by CE

“…Different dual selector systems containing a CD derivative (methyl-b-CD and dimethyl-b-CD) and a new diazacrown-ether derivative (N-(2-(1,4,10,13-tetraoxa-7,16-diazacyclooctadecan-7-yl)propanoyl)glycine) were studied in the enantioselective separation of tryptophan methyl ester and tyrosine methyl ester enantiomers by Elek et al [48] (Table 1).…”