Premium
Analysis of vitamin E and its oxidation products by HPLC with electrochemical detection
Author(s) -
Yamauchi Ryo,
Noro Hiroki,
Shimoyamada Makoto,
Kato Koji
Publication year - 2002
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-002-0926-y
Subject(s) - chemistry , vitamin e , chromatography , alpha tocopherol , high performance liquid chromatography , chemiluminescence , antioxidant , organic chemistry
A sensitive HPLC procedure with postcolumn reduction and electrochemical detection was developed for the analysis of vitamin E and its oxidation products, α‐tocopherylquinone, epoxy‐α‐tocopherylquinones, and 8a‐(lipid‐dioxy)‐α‐tocopherones. After the separation on a reversed‐phase column, on‐line zinc‐catalyzed reduction allowed the detection of α‐tocopherylquinone and epoxy‐α‐tocopheryl‐quinones, whereas platinum‐catalyzed reduction allowed the detection of 8a‐(lipid‐dioxy)‐α‐tocopherones. The lowest detectable level of each compound was about 0.2 pmol at the signal‐to‐noise ratio of 3. This method was applied to the detection of α‐tocopherol products in peroxidized human plasma. When the plasma was peroxidized by the addition of a free radical initiator, peaks corresponding to α‐tocopherylquinone, epoxy‐α‐tocopherylquinones, and the addition products of α‐tocopherol with peroxyl radicals derived from cholesteryl ester hydroperoxides and PC hydroperoxides were observed. The amount of these oxidation products in the plasma increased with the depletion of endogenous α‐tocopherol. The results indicate that the method is useful to detect the oxidation products formed by the peroxyl radical‐trapping reactions of α‐tocopherol in biological systems.