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Separation of α‐, β‐, γ‐, δ‐tocopherols and α‐tocopherol acetate on a pentaerythritol diacrylate monostearate‐ethylene dimethacrylate monolith by capillary electrochromatography
Author(s) -
Chaisuwan Patcharin,
Nacapricha Duangjai,
Wilairat Prapin,
Jiang Zhengjin,
Smith Norman W.
Publication year - 2008
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/elps.200700689
Subject(s) - monolith , capillary electrochromatography , pentaerythritol , chemistry , chromatography , tocopherol , electrochromatography , azobisisobutyronitrile , organic chemistry , polymer chemistry , capillary electrophoresis , polymer , copolymer , vitamin e , antioxidant , fire retardant , catalysis
This work reports the first use of a monolith with method development for the separation of tocopherol (TOH) compounds by CEC with UV detection. A pentaerythritol diacrylate monostearate‐ethylene dimethacrylate (PEDAS‐EDMA) monolithic column has been investigated for an optimised condition to separate α‐, β‐, γ‐ and δ‐TOHs, and α‐tocopherol acetate (TAc). The PEDAS‐EDMA monolith showed a remarkably good selectivity for separation of the TOH isomers including the β‐ and γ‐isomers which are not easily separated by standard C8 or C18 particle‐packed columns. Retention studies indicated that an RP mechanism was involved in the separation on the PEDAS‐EDMA column, but polar interactions with the underlying ester and hydroxyl groups enhanced the separation of the problematic β‐ and γ‐isomers. Separation of all the compounds was achieved within 25 min using 3:10:87 v/v/v 100 mM Tris buffer (pH 9.3)/methanol/ACN as the mobile phase. The method was successfully applied to a pharmaceutical sample with recoveries from 93 to 99%. Intraday and interday precisions (%RSD) for peak area and retention time were less than 2.3. LODs for all four TOHs and TAc were below 1 ppm.