TY - JOUR
T1 - Distinction of synthetic dl-α-tocopherol from natural vitamin E (d-α-tocopherol) by reversed-phase liquid chromatography. Enhanced selectivity of a polymeric C18 stationary phase at low temperature and/or at high pressure
AU - Yui, Yuko
AU - Miyazaki, Shota
AU - Ma, Yan
AU - Ohira, Masayoshi
AU - Fiehn, Oliver
AU - Ikegami, Tohru
AU - McCalley, David V.
AU - Tanaka, Nobuo
PY - 2016/1/20
Y1 - 2016/1/20
N2 - Separation of diastereomers of dl-α-tocopherol was studied by reversed-phase liquid chromatography using three types of stationary phases, polymeric ODS, polymeric C30, and monomeric ODS. Polymeric ODS stationary phase (Inertsil ODS-P, 3. mmID, 20. cm) was effective for the separation of the isomers created by the presence of three chiral centers on the alkyl chain of synthetic dl-α-tocopherol. Considerable improvement of the separation of isomers was observed on ODS-P phase at high pressure and at low temperature. Complete separation of four pairs of diastereomers was achieved at 12.0. °C, 536. bar, while three peaks were observed when the separation was carried out either at 12.0. °C at low pressure or at 20. °C at 488. bar. Higher temperature (30.0. °C) with the ODS-P phase resulted in only partial separation of the diastereomers even at high pressure. Only slight resolution was observed for the mixture of diastereomers with the C30 stationary phase (Inertsil C30) at 12.0. °C and 441. bar, although the stationary phase afforded greater resolution for β- and γ-tocopherol than ODS-P. A monomeric C18 stationary phase did not show any separation at 12.0. °C and 463. bar. The results suggest that the binding site of the polymeric ODS-P phase is selective for flexible alkyl chains that provided the longest retention for the natural form, (R,R,R) form, and the enantiomer, (S,S,S) form, of dl-α-tocopherol.
AB - Separation of diastereomers of dl-α-tocopherol was studied by reversed-phase liquid chromatography using three types of stationary phases, polymeric ODS, polymeric C30, and monomeric ODS. Polymeric ODS stationary phase (Inertsil ODS-P, 3. mmID, 20. cm) was effective for the separation of the isomers created by the presence of three chiral centers on the alkyl chain of synthetic dl-α-tocopherol. Considerable improvement of the separation of isomers was observed on ODS-P phase at high pressure and at low temperature. Complete separation of four pairs of diastereomers was achieved at 12.0. °C, 536. bar, while three peaks were observed when the separation was carried out either at 12.0. °C at low pressure or at 20. °C at 488. bar. Higher temperature (30.0. °C) with the ODS-P phase resulted in only partial separation of the diastereomers even at high pressure. Only slight resolution was observed for the mixture of diastereomers with the C30 stationary phase (Inertsil C30) at 12.0. °C and 441. bar, although the stationary phase afforded greater resolution for β- and γ-tocopherol than ODS-P. A monomeric C18 stationary phase did not show any separation at 12.0. °C and 463. bar. The results suggest that the binding site of the polymeric ODS-P phase is selective for flexible alkyl chains that provided the longest retention for the natural form, (R,R,R) form, and the enantiomer, (S,S,S) form, of dl-α-tocopherol.
KW - Diastereomer
KW - dl-α-Tocopherol
KW - High pressure
KW - Low temperature
KW - Polymeric ODS
KW - Reversed-phase LC
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U2 - 10.1016/j.chroma.2016.04.076
DO - 10.1016/j.chroma.2016.04.076
M3 - Article
AN - SCOPUS:84992304020
JO - Journal of Chromatography
JF - Journal of Chromatography
SN - 0021-9673
ER -