Spectroscopic studies of the interaction between methylene blue-naphthol orange complex and anionic and cationic surfactants

Shunzo Yamamoto, Serina Kobashi, Ken ichiro Tsutsui, Yoshimi Sueishi

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)


Initially, the absorbance of MB at 665 nm decreased rapidly with increasing sodium dodecyl sulfate (SDS) concentration, but increased gradually above about 2.3 × 10-3 M. However, the absorbance of MB was almost independent of the cetyltrimethylammonium bromide (CTAB) concentration. On the other hand, the absorbance of NpO was affected by addition of CTAB in a similar manner to the change in MB-SDS system, but not by addition of SDS. The absorption band of MB showed a small red-shift and a decrease in intensity upon addition of NpO, while that of NpO showed only the decrease in the intensity upon the addition of MB. These spectral changes were attributed to the formation of complexes between these dyes. The effects of anionic and cationic surfactants on the absorption spectra of mixtures of MB and NpO were also examined. Contrary to the effects on the absorption spectrum of MB and NpO, respectively, the absorbances of MB and NpO in the mixtures were changed with the additions of both anionic and cationic surfactants. The spectral changes were explained by changes in the forms of MB and NpO in the solutions with increasing surfactant concentrations.

Original languageEnglish
Pages (from-to)302-306
Number of pages5
JournalSpectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Issue number2
Publication statusPublished - Feb 2007
Externally publishedYes


  • Aggregation
  • Complex
  • Ion pair
  • Methylene blue
  • Micelle
  • Surfactants
  • α-Naphthol orange

ASJC Scopus subject areas

  • Analytical Chemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Spectroscopy


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