Separation of alpha-, beta-, gamma-, delta-tocopherols and alpha-tocopherol acetate on a pentaerythritol diacrylate monostearate-ethylene dimethacrylate monolith by capillary electrochromatography

Electrophoresis. 2008 Jun;29(11):2301-9. doi: 10.1002/elps.200700689.

Abstract

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 alpha-, beta-, gamma- and delta-TOHs, and alpha-tocopherol acetate (TAc). The PEDAS-EDMA monolith showed a remarkably good selectivity for separation of the TOH isomers including the beta- and gamma-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 beta- and gamma-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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acrylates / chemistry
  • Capillary Electrochromatography / methods*
  • Methacrylates / chemistry
  • Stearates / chemistry
  • Tocopherols / isolation & purification*
  • alpha-Tocopherol / analogs & derivatives*
  • alpha-Tocopherol / isolation & purification*
  • beta-Tocopherol / isolation & purification*
  • gamma-Tocopherol / isolation & purification*

Substances

  • Acrylates
  • Methacrylates
  • Stearates
  • pentaerythritol diacrylate monostearate
  • ethylene dimethacrylate
  • gamma-Tocopherol
  • beta-Tocopherol
  • alpha-Tocopherol
  • delta-tocopherol
  • Tocopherols