### Tuesday, 24 May 2005 - 11:35 AM

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### This presentation is part of: Physical Organic

### Determining the distribution of an antioxidant between the oil, interfacial and aqueous regions of food-like emulsions stabilized by C12E6

**Krishnan Gunaseelan** and Laurence S. Romsted. Rutgers University, Piscataway, NJ
We have developed a new approach for estimating the distributions of antioxidants in opaque, surfactant based, macroemulsions based on the pseudophase model for homogenous microemulsions. The distribution of *t*-butylhydroquinone, TBHQ, in emulsions composed of tributyrin, C_{12}E_{6}, and acidic water is described by two partition constants between the oil and interfacial, *P*_{O}^{I}, and the water and interfacial, *P*_{W}^{I}, regions. To estimate values for *P*_{O}^{I} and *P*_{W}^{I} requires fitting two independent data sets with two independent mathematical relations and solving two equations simultaneously. One data set was obtained by electrochemical determination of the observed rate constant, *k*_{obs}, for reaction of TBHQ with an arenediazonium ion probe as a function of C_{12}E_{6} volume fraction. The second data set was obtained by determining the partition constant, *P*_{O}^{W}, of TBHQ between tributyrin and water in the absence of surfactant by UV-Visible spectrometry, *P*_{O}^{W} = 0.015. The values of the partition constants in the emulsion are: *P*_{O}^{I} = 11 and *P*_{W}^{I} = 7.11 x 10^{2}. Application of this approach to a variety of antioxidants in emulsions containing different food oils and emulsifiers should provide new insight into the factors controlling antioxidant distributions and may lead to a development of a new scale of antioxidant efficiency.

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