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Effect of the Electrolyte Concentration on Cation Binding in Aqueous Surfactant Solutions
Author(s) -
Jakubowska Anna
Publication year - 2006
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200600237
Subject(s) - chemistry , electrolyte , aqueous solution , inorganic chemistry , pulmonary surfactant , micelle , electrospray ionization , monomer , ion , sodium , mass spectrometry , chromatography , organic chemistry , biochemistry , electrode , polymer
Electrospray ionisation mass spectrometry (ESI‐MS) is used for the qualitative and quantitative study of ion binding to interfaces. The ESI‐MS measurements are carried out in aqueous solutions of sodium dodecyl sulphate (SDS) in the presence of NaCl, NH 4 ClO 4 , KCl, or Mg(ClO 4 ) 2 . The effect of the electrolyte concentration on the fractions, y cation +, of the DS − monomers bound to the cations is shown. Moreover, the binding stability of different cations with DS − monomers is determined versus the electrolyte concentration. This stability and the y Na +values (the Na + ions derived from SDS), estimated in the presence of a given electrolyte, are quantitatively correlated with the electrolyte cation effect on the water structure. We also present calibration curves from which the molar concentrations of the sodium ions (derived from SDS) and of the other cations (derived from the electrolyte), bound to the SDS‐micelle surface at a given electrolyte concentration, can be obtained. Besides, specific ion effects (Hofmeister effects) are considered for 1:1 electrolytes.