We report the use of a molecular micelle for the simultaneous separation and concentration of neutral and hydrophobic analytes using micellar affinity gradient focusing (MAGF). The technique, MAGF, combines the favorable features of micellar electrokinetic chromatography (MEKC) and temperature gradient focusing (TGF). The focusing of neutral coumarin analytes was accomplished by the use the molecular micelle, poly (sodium undecenyl sulfate), poly-SUS. Concentration enhancements of 10-fold to 25-fold per minute were achieved for focusing of the coumarin dyes. The effect of varying the temperature gradient on the resolution of 2 of the coumarins dyes was also investigated, demonstrating that improved resolution could be achieved by reducing the steepness of the temperature gradient. In addition, with scanning-mode MAGF (in which the peaks are sequentially scanned past a fixed detection point by varying the buffer counter-flow velocity), the use of poly-SUS was shown to produce repeatable and quantitative analyte peaks, making quantitative separations possible with the MAGF technique. Finally, it was shown that peak areas could be increased in scanning MAGF by reducing the scan rate so that the sensitivity of the method can be adjusted as needed.
Citation: Analytical Chemistry
Pub Type: Journals
capillary electrophoresis, micellar electrokinetic chromatography, molecular micelles, temperature gradient focusing