Hi. You should provide some details on the emulsion formulation in the first place: Is it (i) a tocopherol-in-water emulsion, (ii) an oil-in-water emulsion containing tocopherol in the oil phase (comprising, say, of oil+tocopherol)? Also some info on the emulsifier used would be welcome (not forgeting that tocopherols are also somehow surface-active). Can you give me a reference for the LC method you chose to follow?

Thanks Christos..

I'm preparing oil-in-water emulsion, Tocopherol in oil like sunflower oil. And the emulsifier i'm using is protein. I want to analyse with HPLC (Isocratic flow with C18 column)..

The problem is that tocopherols tend to adsorb at the oil-water inetrface, plus they could, under conditions, be somehow water soluble, so you should always consider a partition of your material between oil, interface and even aqueous phase (and tune your extraction methodology accordingly). Working with emulsions for many years, I think that one of the toughest quests is to extract the interface-adsorbed materials. Even if you displace them with surfactants, it is difficult to be sure that you do it right, especially when you do not have an in-depth understanding of the system. This is where many extraction methodologies from emulsions fail.

An interesting approach is the one by Gornas et al (Acta Sci Pol Tech Aliment 5, 157-164, 2006), where pure oil containing tocopherol is saponified, then the tocopherols are extracted and measured. Not a bad idea for your centrifuged cream. I will make a more thorough search on this and come back to you.

PS Bear in mind that tocopherol(s) are a family of molecules, so you could have multiple peaks in your chromatogram (I do not know if your added tocopherol is a single molecule or a tocopherol mix).

Thanks for the explanation Christos.

I'm using 98 % pure tocopherol liquid. Mostly I will used to get a single peak for tocopherol. But in sometimes, I used to get a small peak along the major tocopherol peak. I attached a pdf, you could see a small peak near the major peak at 21.83 min.

I read the paper you mentioned. But they were using the DPPC membrane for separating the tocopherol content from the surfactant and determining the concentration with fluorescence..

Joseph, please contact me at [email protected] so we can continue his discussion in a private space.