Abstract
Experiments investigating the effects of tetraalkylammonium (TAA) ions on the micellar electrokinetic chromatography (MEKC) of aniline and a series of 12 substituted anilines using sodium n-dodecyl sulfate (SDS) are reported. Increasing the concentration of tetramethylammonium (TMA) ions results in increases in the elution range ( t mc− t 0) and the migration times for the aniline solutes. In contrast the addition of small concentrations of tetrabutylammonium (TBA) ions leads to changes in the elution order and a considerable improvement in the separation of the anilines without a significant increase in the elution range. Further increases in the concentration of TBA ions to levels above 1/3 the concentration of SDS narrows the elution range and has a detrimental effect on the separation. The effects of the TBA ions are attributed to changes in the structure of the SDS micelles resulting in a more open and disordered SDS micelle which enhances the transfer of anilines with polar ring substituents into the micelle.
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