Rapid quantification of alpha-tocopherol in plasma and low- and high-density lipoproteins.
We have developed two methods for measuring the alpha-tocopherol content in plasma and lipoproteins (LDL and HDL). In procedure 1, plasma or lipoproteins are deproteinized with ethanol containing delta-tocopherol as internal standard and then extracted with hexane or ethyl acetate. The organic layer is removed and evaporated, and the residue is redissolved in methanol and injected into a reversed-phase HPLC. In procedure 2, plasma or lipoproteins are diluted in a methanol and ethanol mixture containing the same internal standard. The solution is vortex-mixed, centrifuged, and directly injected into the column. The tocopherols are eluted with an isocratic methanol mobile phase at a flow rate of 1 mL/min and detected by fluorescence (lambda(exc)= 295 nm, lambda(em)= 330nm). Recoveries are approximately 100% in both cases. Between-run CVs were 8.39% for procedure 1 and 6.55% for procedure 2. Small sample requirement, simplicity of sample preparation, short assay time, and good reproducibility make procedure 2 ideal for clinical or research use. This method was applied to determination of alpha-tocopherol in plasma of patients whose diet was supplemented with alpha-tocopherol and in LDL and HDL.
Teissier
E
E
SERLIA et INSERM, Institut Pasteur, Lille, France.
Walters-Laporte
E
E
Duhem
C
C
Luc
G
G
Fruchart
J C
JC
Duriez
P
P
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004355:Drug Stability; D000431:Ethanol; D006801:Humans; D008075:Lipoproteins, HDL / Q000097:blood*; D008077:Lipoproteins, LDL / Q000097:blood*; D000432:Methanol; D012016:Reference Values; D015203:Reproducibility of Results; D014810:Vitamin E / Q000008:administration & dosage / Q000097:blood*
D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D014810:Vitamin E; D000431:Ethanol; D000432:Methanol