MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY OF NEUTRAL SOLUTES WITH MICELLES OF ADJUSTABLE SURFACE-CHARGE DENSITY

Novel micelles with adjustable surface charge density were introduced for micellar electrokinetic capillary chromatography. These micelles are based on the complexation between octylglucoside surfactant and alkaline borate. The surface charge density of the octylglucoside-borate micelles can be conveniently varied by changing the operating parameters such as borate concentration and/or pH of the running electrolyte. This feature permitted the tuning of the elution range, a parameter that largely influences the peak capacity and resolution in micellar electrokinetic capillary chromatography. Furthermore, with its balanced hydrophile-lipophile character, the octylglucoside-borate micellar system allowed the separation of hydrophobic species including herbicides, e.g., prometon, ton, prometryne, propazine and butachlor, and some polyaromatic hydrocarbons. High separation efficiencies were obtained over a wide range of elution conditions, and consequently the detection limit for the herbicides was in the range of 18-52 fmol using UV detection.