Fluorescence of 8-anilinonaphthalene-1-sulfonate and properties of sodium dodecyl sulfate micelles in water-urea mixtures

Elsa B. Abuin, Eduardo A. Lissi, Alexis Aspée, Fernando D. Gonzalez, José M. Varas

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)


8-Anilinonaphthalene-1-sulfonate (ANS) was used as fluorescence probe to study the effects of urea on properties of sodium dodecyl sulfate micellar solutions. The critical micelle concentration (CMC) of the surfactant, the degree of counterion association to the micelles, and the partition constant of ANS between the micelles and the external medium in the vicinity of the CMC were obtained at different urea concentrations ranging from 0 to 8 M. Complementary results regarding the effects of urea on the micelle aggregation number, the E(T)(30) parameter, and the partitioning of ANS between n-octanol and water or water-plus-urea mixtures were also obtained to allow critical evaluation of the ANS fluorescence data. It is concluded that the effect of urea on ANS fluorescence at intermediate surfactant concentrations is due mainly to increased stability of the probe in the aqueous medium. Extrapolation of the data at total ANS incorporation into the micelles allows the conclusion that the intramicellar emission increases slightly on urea addition. This result is attributed to an increase in the microviscosity at the micellar surface resulting from urea-micelle interactions.

Original languageEnglish
Pages (from-to)332-338
Number of pages7
JournalJournal of Colloid and Interface Science
Issue number2
Publication statusPublished - 15 Feb 1997


  • 8-Anilinonaphthalene-1-sulfonate
  • Fluorescence in micelles, effects of urea on
  • Micellar properties, effect of urea on
  • Sodium dodecyl sulfate

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry


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