Jm. Lin et al., Determination of critical micelle concentration of SDS in formamide by capillary electrophoresis, CHROMATOGR, 50(11-12), 1999, pp. 739-744
Using an organic solvent and a surfactant, the uncharged, hydrophobic p-ary
lacetophenones have been separated by micellar electrokinetic chromatograph
y. As an example, the effect of formamide containing sodium n-dodecyl sulfa
te (SDS) on the separation has been studied. Separations of all selected un
charged hydrophobic compounds were shown to be strongly dependent on the co
ncentration of surfactant. It is suggested that if there is no micelle form
ed in the formamide solvent, the uncharged hydrophobic compound cannot be s
eparated even though in the presence of surfactant. The electro-migration o
f solutes was considered zero. After micelle formation, the uncharged compo
unds were partitioned between the micellar and the organic solvent phases.
Neutral molecule partition in and out of micelles depends on the hydrophobi
city of each analyte. Based on this suggestion the critical micelle concent
rations of SDS, di-(ethylhexyl) sodium sulfosuccinate (AOT) and taurodexych
olic acid sodium salt (STDC) in formamide were determined.