Effect of alcohol modifier on micellar electrokinetic chromatography separation

The effect of the addition of normal C1-C5 alcohols on the background elect rolyte on the separation of a set of wide polar aromatic hydrocarbons in mi cellar electrokinetic capillary chromatography (MECC) was examined. Experim ents were carried out with the micellar solution system of sodium dodecyl s ulfate-berate at pH 9.2, containing different amount (0-15%) of C1-C5 alcoh ols separately. For the shorter alkyl chain C1-C3 alcohols, as the content of alcohol increased, the elution window (t(m)/t(o)) increased, and the cap acity factors (k') of all test samples decreased. Comparatively, C4 and C5 alcohols had the different effects. With the content increased t(m)/t(o) in creased first and then decreased, and the k' increased for the most solutes . The results also showed that the alcohol additives had more effect on wea kly polar or hydrophobic compounds than more polar compounds. The addition of alcohol caused the increase of both the number of theoritical plates (N) and the resolution, especially for the hydrophobic compounds.