Separation of α‐tocopherol and its oxidation products by high performance liquid chromatography

Abstract

A very sensitive high performance liquid chromatographic (HPLC) method was developed for the separation of alpha-tocopherol (alpha-T) and its five oxidation products: alpha-tocopheryl quinone (TQ), dimer (D), dihydroxy dimer (DHD), trimer (T) and 9-methoxy-alpha-tocopherone commonly called alpha-tocopheroxide (TO). The separation was achieved on a normal-phase silica-based column (Ultrasphere-Si), using a mobile phase of hexane/chloroform/isopropanol (95:4.5:0.5, v/v/v) at a flow rate of 0.4 ml/min, and the eluants were monitored simultaneously at their maximum absorptions using a variable-wavelength UV detector. The minimum detection limit is 0.01 microgram for alpha-T, TQ and TO, 0.05 microgram for DHD and D, and 0.1 microgram for T/injection. This normal-phase method has the combined advantages of being very sensitive, fast and capable of separating all six compounds at the same time.

Oxidized lipids in the diet are a source of oxidized lipid in chylomicrons of human serum.

“…23 Fatty acid composition of oils and chylomicrons was determined by GLC (Hewlett Packard 5890). 20 Fatty acids were transmethylated with boron trifluoride methanol and were analyzed by GLC equipped with a hydrogen flame ionization detector and an SP-2330 fused silica capillary column (Supelco).…”

Protein and Lipid Oxidative Stresses During Cheese Manufacture

“…␣-tocopherol (TH) is the most abundant lipophylic milk antioxidant (Erickson and others 1964) and is principally involved in scavenging peroxyl radicals (Burton and Ingold 1986). TH oxidation, occurring during the early phase of lipid oxidation, leads to the formation of a number of by-products (Ha and Csallany 1988) and, among them, ␣tocopherolquinone is the most abundant (Bieri and Tolliver 1981). Lipid oxidation reactions, during the termination phase, produce aldehydes, ketones, alcohols, acids, and hydrocarbons.…”

Analysis of tocopherols and phytosterols in vegetable oils by HPLC with evaporative light‐scattering detection

“…Several groups of researchers have used HPLC with fluorometric detectors to measure tocopherols (11)(12)(13)(14)(15). Ultraviolet detection (UV) with HPLC has also been used (16)(17)(18). A collaborative study sponsored by the International Union of Pure and Applied Chemistry (IUPAC) determined the tocopherol contents of oil by HPLC with both fluorescence and UV detection techniques (19).…”