Chiral capillary electrophoresis: Facts and fiction on the reproducibility of resolution with randomly substituted cyclodextrins

Publisher Website
Google Scholar
Abstract
Comparative enantioseparation of the enantiomers of 1,1'‐binaphthyl‐2,2'‐diyl hydrogen phosphate was performed with cyclodextrin (CD)‐modified capillary electrophoresis (CE). Two single isomers, β‐CD, heptakis(2,3,6‐tri‐O‐methyl)‐β‐CD (TM‐β‐CD), and heptakis(2,6‐di‐O‐methyl)‐β‐CD (DM‐β‐CD) of 98% purity as well as heptakis(2,3‐di‐O‐acetyl)‐β‐CD were used and compared in terms of resolution power to randomly methylated and corresponding acetylated β‐CDs, which were synthesized in our laboratory. The methylated ones were characterized by means of matrix‐assisted laser desorption/ionization‐time of flight‐(MALDI‐TOF) mass spectrometry. By testing defined mixtures of single isomers and comparing their resolution power to randomly substituted CDs of similar degree of substitution we could show, that a simple characterization by the average molecular degree of substitution (DS) is not sufficient. In order to get reproducible results, a clearly defined substitution pattern is necessary, which is not given using randomly substituted CDs. Taken together, a validation of a chiral separation with “undefined” CD derivatives is almost impossible.

This publication has 0 references indexed in Scilit: