Determination of RS,E/Z-tocotrienols by HPLC.
Synthetic alpha-tocotrienol was separated into four geometrical E/Z side chain isomers by preparative HPLC (permethylated beta-cyclodextrin phase). The isolated isomers were resolved in ethylene glycol dimethyl ether, converted into the corresponding methyl ether using dimethyl sulfate, and the tocotrienol methyl ethers were extracted with n-hexane. A subsequent HPLC separation on a chiral phase (adsorbent cellulose derivated with 3,5-dimethyl phenyl carbamate) discriminates between the enantiomers of each E/Z side chain isomer, achieving the complete resolution of the eight occurring synthetic RS,E/Z-alpha-tocotrienols. The method can be shortened by omitting the preparative separation of the E/Z tocotrienol isomers prior to the chromatography on the chiral dimethyl phenyl carbamate phase. The simplified method achieved the following separation: RS,E/Z-alpha-tocotrienol separated into five peaks, RS,E/Z-beta-tocotrienol into eight, RS,E/Z-gamma-tocotrienol into six and RS,E/Z-delta-tocotrienol into eight peaks. The naturally occurring R,E-E-tocotrienol isomer could be identified within the synthetic RS,E/Z-isomers by co-chromatography with tocotrienol methyl ethers derived from natural sources, respectively.
Drotleff
A M
AM
Center of Food Science, Department of Chemical Analysis and Endocrinology, Hannover School of Veterinary Medicine, Germany.
Ternes
W
W
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D012680:Sensitivity and Specificity; D013237:Stereoisomerism; D024508:Tocotrienols; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000032:analysis*
D024508:Tocotrienols; D014810:Vitamin E; C082032:tocotrienol, alpha