Study on strongly polarized water in AOT reversed micelles by fluorescence probes and analytical application of AOT reversed micelles

The basicity of water in AOT (sodium bis(2-ethyl-1-hexyl)sulfosuccinate) reversed micelles has been investigated by tetracycline-Eu3+ complex and tetracycline as fluorescence probes. The results obtained show that the variation in luminescence intensity and absorption spectra of the compounds together with a decrease in water content of the reversed micelles coincides with an increase in the pH value of the bulk water. It indicates that with a gradual decrease in the R([H2O]/[AOT]) value water molecules become more polarized, like the hydroxide ion. The apparent pH in reversed micelles at R = 1.5–2.0 is ca. 9. The properties of the water pool in reversed micelles can be utilized for sensitive detection of tetracycline and analogues without addition of alkaline solutions. The detection limit is in the subnanogram range.