Strategies for enantioseparations of catecholamines and structurally related compounds by capillary zone electrophoresis using sulfated β-cyclodextrins as chiral selectors

Abstract

Strategies for simultaneous enantioseparations of three catecholamines (DL-norepinephrine, DL-epinephrine, and DL-isoproterenol) and three structurally related compounds (DL-octopamine, DL-synephrine, and DL-norephedrine) by CZE using sulfated beta-CDs as chiral selectors were investigated. Four different separation modes were attempted: (I) using randomly sulfate-substituted beta-CD (MI-S-beta-CD) at relatively low concentrations in a high-concentration phosphate buffer at low pH in the normal polarity mode, (II) using MI-S-beta-CD at high concentrations at low pH in the reversed polarity mode, (III) using MI-S-beta-CD at moderately high concentrations in a phosphate buffer at neutral pH in the normal polarity mode, and (IV) using the single isomer heptakis(2,3-dihydroxy-6-O-sulfo)-beta-CD (SI-S-beta-CD) at low to moderately high concentrations in a high-concentration BGE at low pH in the normal polarity mode. Among them, enantioseparation of these cationic solutes was best achieved under the conditions of mode (II). In mode (II) and mode (III), temperature is an important factor affecting the enantioresolution of norepinephrine. In mode (I) and mode (IV), the use of a high-concentration BGE (150-200 mM) is crucial for effective enantioseparation of these cationic solutes with sulfated beta-CDs. Comparative studies of enantioseparations of these cationic solutes with MI-S-beta-CD and SI-S-beta-CD reveal that the sulfate substituents of MI-S-beta-CD located at the C(2)- position interact strongly with the diol moiety of catecholamines.

Capillary electrophoresis and microchip capillary electrophoresis with electrochemical and electrochemiluminescence detection

“…The resulting electrode displays a highly sensitive AD of amino acids, based on the copper dissolution facilitated by the strong activity of amino acids as ligands of Cu(II). Lin et al [55] investigated four different separation strategies for simultaneous enantioseparations of three catecholamines (DL-norepinephrine, DL-epinephrine, and DL-isoproterenol) and three structurally related compounds (DL-octopamine, DL-synephrine, and DL-norephedrine) by CE using sulfated beta-CDs as chiral selectors.…”

Effect of temperature on the enantioselectivity of basic analytes using CE with sulfated β‐cyclodextrins

“…By comparing the tested compounds, the enantioseparations became better and better from -NH 2 to -NHR (R = alkyl groups). For instance, the enantioselectivity was always equal to 1.000 for Norepine under the whole experimental conditions (it could be totally separated by S-b-CD under other conditions [23] or by HP-b-CD which was not shown in our experiments). There could be achieved baseline separation for Epine and Isoprot; however, the separation resolution of Isoprot was better than that of Epine.…”

“…For them, (+)-enantiomers had greater affinities with S-b-CD and were first eluted, which were also according to the previous work by Lin et al [23].…”

Simultaneous separation of epinephrine and norepinephrine enantiomers by EKC: Application to the analysis of pharmaceutical formulations

“…However, the aim of most of these works was to characterize commercialized and non-commercialized CDs as chiral selectors achieving a systematic screening of different compounds (including EP and/or NEP). Only in a few articles [4,16,19,22,31,38], the simultaneous separation of EP and NEP enantiomers was studied. Native b-CD or its neutral derivatives (2-hydroxypropyl-b-CD, 2,6-di-O-methyl-b-CD, and 2,3,6-tri-O-methylb-CD) were generally employed using acid buffers (pH from 2.4 to 2.9) although anionic CDs were also used (sulfatedb-CDs) [38].…”