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Separation of alkamides from Echinacea purpurea extracts by cyclodextrin‐modified micellar electrokinetic chromatography
Author(s) -
Gotti Roberto,
Fiori Jessica,
Hudaib Mohammad,
Cavrini Vanni
Publication year - 2002
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200209)23:17<3084::aid-elps3084>3.0.co;2-0
Subject(s) - micellar electrokinetic chromatography , chromatography , cyclodextrin , electrokinetic phenomena , chemistry , capillary electrophoresis
Separation of nine important alkyl methylbutyl‐ and isobutylamides (known as alkamides) obtained from Echinacea purpurea extracts was investigated by using cyclodextrin‐modified micellar electrokinetic chromatography (CD‐MEKC). Hydrophobic alkamides interact strongly with the micelles from the most common surfactants used in MEKC and this lead to predominant partition of the analytes into the micellar phase, resulting in poor resolution. The addition of neutral CDs to the alkaline (10 m M phosphate buffer pH 8.0) micellar system of sodium dodecyl sulfate (SDS), sodium cholate (SC) and sodium deoxycholate (SDC) was found to improve the separation of the studied alkamides. Among the several combinations surfactant/CD, three different systems showed to be particularly effective: SDS/hydroxypropyl‐β‐CD (110 m M /100 m M ) and SC/heptakis (2, 3, 6‐tri‐ O ‐methyl)‐β‐CD (200 m M /40 m M ) which provided a complete separation of the studied compounds, and SDC/heptakis (2, 6‐di‐ O ‐methyl)‐β‐CD. The importance of appropriate surfactant vs. CD concentration ratio as well as that of total concentration of both surfactant and CD was considered. The optimization of the separation was performed by focussing the need for a rapid separation of nine alkamides diagnostically useful to define the fingerprint of Echinacea species.