Separation of alpha-, beta-, gamma-, delta-tocopherols and alpha-tocopherol acetate on a pentaerythritol diacrylate monostearate-ethylene dimethacrylate monolith by capillary electrochromatography.
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.
Flow Innovation-Research for Science and Technology Laboratories, Department of Chemistry, Faculty of Science, Mahidol University, Bangkok, Thailand.
Patcharin
P
Chaisuwan
Duangjai
D
Nacapricha
Prapin
P
Wilairat
Zhengjin
Z
Jiang
Norman W
NW
Smith
D000179:Acrylates / Q000737:chemistry; D053801:Capillary Electrochromatography / Q000379:methods*; D008689:Methacrylates / Q000737:chemistry; D013228:Stearates / Q000737:chemistry; D024505:Tocopherols / Q000302:isolation & purification*; D024502:alpha-Tocopherol / Q000031:analogs & derivatives* / Q000302:isolation & purification*; D024503:beta-Tocopherol / Q000302:isolation & purification*; D024504:gamma-Tocopherol / Q000302:isolation & purification*
D000179:Acrylates; D008689:Methacrylates; D013228:Stearates; C531048:pentaerythritol diacrylate monostearate; C004919:ethylene dimethacrylate; D024504:gamma-Tocopherol; D024503:beta-Tocopherol; D024502:alpha-Tocopherol; C479072:delta-tocopherol; D024505:Tocopherols