Objective. Vitamin E is mainly composed of four tocopherols (-, -, - and -T) and four tocotrienols (-, -, - and -T3), i.e. tocochromanols. Scarcely, a few further minor compounds were described in the scientific literature. Here, we aimed to develop a method to screen for these minor tocochromanols, to enrich and/or isolate them, and to assign their exact structures by NMR and MS techniques. Methods used. High gram-amounts of edible oils were carefully saponified (inert gas, addition of antioxidant) and the unsaponifiable matter was separated. Aliquots of ~0.5-1 g unsaponifiable matter or the content from vitamin E capsules were repeatedly fractioned by countercurrent chromatography. Structure-dependent elution volumes of - to -tocopherols and tocotrienols were developed and used to predict the elution range of tocodienols and tocomonoenols, as well as possible co-eluting compounds. After purification, NMR and MS techniques were used for structure determination. Results. Four tocopherols, at least four tocomonoenols, four tocodienols and four tocotrienols were found to be native minor or trace constituents of plant oils. CCC proved to be well-suited for the detection and enrichment/isolation with high purity. Several of these tocochromanols were detected for the first time in the corresponding oil or at all. Structures and positions of double bonds were assigned by NMR and MS methods. Conclusions. Vitamin E minor compounds are more varied than previously anticipated. Their vitamin E activity is widely unknown, but the amounts that were gained will be sufficient to study their role in oils and food.
