Dye solubilization in W/O microemulsions

The solubilization of methylene blue in W/O microemulsions containing n-heptane or isooctane, sodium bis (2-ethylhexyl)sulphosuccinate (AOT) in the presence and the absence of 2-ethylhexanol, was studied. The alcohol transforms the W/O ''made up'' microemulsions into Winsor TI ones; The dye partition between the aqueous phase and the W/O microemulsion mas determined spectrophotometrically. The shift of the maximum absorption wavelength indicates a preferential transfer of the dimer dye from the aqueous to microemulsion phase. The preferential transfer is apparent for the concentrations range of the dye within which the solubilization of the methylene blue in the reverse micelles is far from Lire maximum value.