Separation and determination of corynoxine and corynoxine B using chiral ionic liquid and hydroxypropyl‐β‐cyclodextrin as additives by field‐amplified sample stacking in capillary electrophoresis

Abstract

A sensitive, fast, and effective method, field-amplified sample stacking (FASS) in capillary electrophoresis, has been established for the separation and determination of corynoxine and corynoxine B. Hydroxypropyl-β-CD (HP-β-CD) and tetrabutylammonium-L-glutamic acid (TBA-L-Glu) were used as additives in the separation system. Electrokinetic injection was chosen to introduce sample from inlet at 10 kV for 50 s after a water plug (0.5 psi, 4 s) was injected to permit FASS. The running buffer (pH 6.1) was composed of 40 mM sodium dihydrogen phosphate solution, 130 mM HP-β-CD, and 10 mM TBA-L-Glu and the separation voltage was 20 kV. Under the optimum conditions, corynoxine and corynoxine B were successfully enriched and separated within 12 min and the sensitivity was improved approximately by 700-900 folds. Calibration curves were in a good linear relationship within the range of 62.5-5.00 × 10 ng/mL for both corynoxine and corynoxine B. The limits of detection (S/N = 3) and quantitation (S/N = 10) were 14.9, 45.2 ng/mL for corynoxine and 11.2, 34.5 ng/mL for corynoxine B, respectively. Finally, this method was successfully applied for the determination of corynoxine and corynoxine B in the stems with hooks of Uncaria rhynchophylla and its formulations.

On‐line synergistic stacking in capillary zone electrophoresis featuring field‐amplified sample stacking and micelle to cyclodextrin stacking in the determination of two alkaloids in complicated matrix samples

“…The concentration of electrolyte in BGE plays a significant role in the FASS process . Therefore, different NH 4 AC concentrations (40, 50, 60, 70, and 80 mM) were investigated in this study.…”

Simultaneous separation and determination of hirsutine and hirsuteine by cyclodextrin‐modified micellar electrokinetic capillary chromatography

“…The pH was an important factor for separation in the CD‐MEKC because the pH has impact on the electroosmotic flow (EOF) and the amount of charge of the analytes in the buffer, it can influence the migration time and resolution of the analytes as well . In this study, the effects of pH on the resolution and migration time were tested in the range 6.5–7.5 with the BGE consisting of 40 mM phosphate buffer solution, 150 mM DM‐β‐CD, 3 mM ED‐β‐CD and 30 mM SC.…”

Chiral Selectors in Capillary Electrophoresis: Trends during 2017–2018

“…β-CD derivatives, i.e., neutral (hydroxyethyl-, hydroxypropyl- and methyl-) and anionic (carboxymethyl-, and sulphated-) [21,22,23,24,25,26,27,28,29,30,31,32,33] derivatives were the most commonly used CSs reported. Other commercially-available modified CDs or laboratory-prepared modified CDs with known synthesis were reported.…”

“…Three classes of low molecular weight compounds were reported as CS. These are CS with a central ion (i.e., ligand exchangers [78,79], an ion-pair selector [80]), ILs [31,81,82] and a tetracycline antibiotic [83]. An IL implemented in a ligand exchanger is discussed under ILs.…”

“…We note that an achiral IL derivatised β-CD was reported (see Section 2.1.1.2) in 2018. During this review period, amino acid or amide based chiral ILs were mainly used in conjunction with a macromolecule (mostly a CD) [31,60,82,90,91,92,93]. In general, chiral separations were obtained only with both IL and macromolecule in the BGS.…”