Abstract
The gel filtration of a micellar solution on Sephadex G-50 was applied for the study of partition of methyl, ethyl and butyl parabens between the micellar and aqueous phases. When, after the gel layer having been pre-equilibrated with 8 mM sodium lauryl sulfate (SLS), SLS solutions solubilizing alkyl parabens were eluted with 8 mM SLS nearly equal to critical micelle concentration (cmc) as an eluent, decomposition of micelles might be prevented. In this case, however, liberation of alkyl paraben from a micellar phase was observed, accordingly to a property of alkyl paraben or a sample volume (correlated to the gel volume). It might therefore be difficult to investigate quantitatively the distribution state of alkyl paraben in micelles. It was tried that the gel pre-equilibrated with a large sample was eluted with water as an eluent (the so-called tail analysis). As a result, it was found from the elution curves of alkyl parabens obtained by the tail analysis that partition ratios of the alkyl parabens between the micellar and aqueous phases may be determined. These results correspond to the data from the solubility method. However, information from the solubility method is only obtained about the saturated solution from the nature of experiment. From gel filtration, on the other hand, it may be possible to get information not only about a partition ratio for a solute unsaturated in a detergent solution, but also about the state of detergent micelles.
