Determination of α-tocopherol and α-tocopherylquinone in rat tissues and plasma by high-performance liquid chromatography with electrochemical detection

Hideko Kanazawa, Chizuko Miyata, Yoshiko Nagata, Shiro Urano, Yoshikazu Matsushima

Research output: Contribution to journalArticle

19 Citations (Scopus)

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 languageEnglish
Pages (from-to)1462-1466
Number of pages5
JournalChemical and Pharmaceutical Bulletin
Volume48
Issue number10
DOIs
Publication statusPublished - 2000 Jan 1

Keywords

  • HPLC-ED
  • Hyperoxia
  • Rat tissue
  • α-Tocopherol
  • α-Tocopherylquinone

ASJC Scopus subject areas

  • Chemistry(all)
  • Drug Discovery

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