Abstract
α-Tocopherol and α-tocopherylquinone in rat tissues and plasma were determined simultaneously by using high-performance liquid chromatography-electrochemical detection (HPLC-ED) with dual electrodes in the series mode. Biological samples were saponified in the presence of a mixture of butylated hydroxytoluene, ascorbic acid, and pyrogallol and then extracted with hexane. The compounds were separated on a C18 column using a mobile phase containing 95% methanol and 0.05 M sodium perchlorate as the supporting electrolyte. After HPLC separation, α-tocopherylquinone was first reduced at an upstream electrode at -500 mV. Both α-tocopherol and the reduction product of α-tocopherylquinone were then oxidized downstream at +600 mV. Only the downstream electrode current was monitored for the determination. Linearity of the standard curves was obtained over the range 5-30 pmol for α-tocopherol and α-tocopherylquinone. Minimum detectable quantities (S/N of 3) were 0.25 pmol for α-tocopherol and 0.31 pmol for α-tocopherylquinone. The method was applied to analysis of the contents of α-tocopherol and α-tocopherylquinone in rat tissues and plasma. By hyperoxia, the content of α-tocopherol was decreased remarkably in lung, and in contrast, the contents of α-tocopherylquinone were increased in all tissues studied with the exception of plasma, though the content of α-tocopherylquinone in normal rats is quite small. The technique is particularly useful in the quantitation of the oxidation of α-tocopherol in biological samples.
Original language | English |
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Pages (from-to) | 1462-1466 |
Number of pages | 5 |
Journal | Chemical and Pharmaceutical Bulletin |
Volume | 48 |
Issue number | 10 |
DOIs | |
Publication status | Published - 2000 |
Keywords
- HPLC-ED
- Hyperoxia
- Rat tissue
- α-Tocopherol
- α-Tocopherylquinone
ASJC Scopus subject areas
- Chemistry(all)
- Drug Discovery