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A rapid method for the determination of vitamin E forms in tissues and diet by high‐performance liquid chromatography using a normal‐phase diol column
Author(s) -
Kramer John K. G.,
Blais Lisa,
Fouchard Robert C.,
Melnyk Roman A.,
Kallury Krishna M. R.
Publication year - 1997
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/s11745-997-0040-1
Subject(s) - saponification , chromatography , chemistry , tocopherol , vitamin e , hexane , diol , high performance liquid chromatography , biochemistry , organic chemistry , antioxidant
This paper describes a simple method for the analysis of tocopherols in tissues by which frozen tissues −70°C were pulverized at dry ice temperatures (−70°C) and immediately extracted with hexane. There was no need to remove the coeluting lipids from tissues by saponification, since at that level of neutral lipids in the sample, there was no reduction in fluorescence response. For the analysis of oil, in which large amounts of neutral lipids were coextracted, a 20% reduction of fluorescence response was observed, but the response was equal for all tocopherol forms, and was appropriately corrected. Saponification was used only when tocopherol esters were present, and only after an initial hexane extraction to remove the free tocopherols in order to avoid their loss by saponification, particularly non α‐tocopherol and tocotrienols. All the tocopherols and tocotrienols were separated on a normal‐phase diol (epoxide) column that gave consistent and reproducible results, without the disadvantages of nonreproducibility with silica columns, or the lack of separation with reversed‐phase columns. The tocopherols were quantitated by using a tocopherol form not present in the sample as an internal tocopherol standard, or using an external tocopherol standard if all forms were present, or when the sample was saponified. Piglet heart and liver samples showed the presence of mainly α‐tocopherol, with minor amounts of β‐ and γ‐tocopherol and α‐tocotrienol, but no δ‐tocopherol. Only small amounts of tocopherol esters were present in the liver but not in the heart.