DETERMINATION OF CRITICAL MICELLE CONCENTRATION OF SURFACTANTS USING A NEAR-INFRARED HYDROPHOBICITY PROBE

A near-infrared (NIR) dye has been used for the determination of critical micelle concentrations (CMC) of surfactants. This NIR dye displays significant changes in its absorption spectra dependent on the hydrophobicity of the microenvironment around the dye molecule. The absorption spectra of this NIR dye show two distinct maxima which can be used in determining hydrophobicity. The NIR hydrophobicity probe detects the changes in the microenvironment hydrophobicity accompanying micelle formation. The determined CMC values are in good agreement with values obtained using other techniques. The major advantage of this NIR method lies in the inherently low interference of the NIR spectral region. © 1991.