In order to investigate effect of the inhomogeneous dispersion system on photogeneration and decay dynamics of the tocopheroxyl radical (Toc(center dot)), transient absorption and steady-state and time-resolved EPR measurements on photolysis of vitamin E (VE) were carried out. Tocopherol (TocH) is photo-decomposed through electron-detachment in the excited state and the subsequent proton releasing, which produce Toc(center dot) and the solvated electron (e(solv)(-)). The decay of Toc(center dot) is explained by (i) a rapid decay within 2 mu s by recombination between Toc(center dot) and e(solv)(-), (ii) a second-order decay observed in the range of 5-150 mu s by reaction between Toc(center dot) and the superoxide anion radical (O(2)(center dot-)), and (iii) a slow decay in >10 ms by bimolecular self-quenching of Toc(center dot). The Toc(center dot) decay in the VE emulsion was very different from that in the homogeneous solution. In the emulsion, the Toc(center dot) yield was small, the contribution of the reaction with O(2)(center dot-) was rather small, and the decay due to the bimolecular reaction of Toc(center dot) was much accelerated. In the emulsion, Toc(center dot) could not be detected by steady-state EPR, although it could in ethanol. These differences should be caused by the oil-droplet formation in the emulsion. From these results, we can expect that the photostability of the VE emulsion is superior to that of the VE homogeneous solutions. (C) 2010 Elsevier By. All rights reserved.