INFINITE ELUTION RANGE IN MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY USING A NONIONIC ANIONIC MIXED MICELLAR SYSTEM/

The feasibility of increasing the elution range in micellar electrokin etic capillary chromatography (MEKC) was investigated using a nonionic /anionic mixed micellar system. The micellar ''pseudostationary'' phas e was comprised of a mixture of nonionic (poly(oxyethylene)(23) dodeca nol) and anionic (sodium dodecyl sulfate) surfactants. Variation in po ly(oxyethylene)(23) dodecanol (Brij 35, Aldrich) concentration affecte d the electroosmotic and micellar electrophoretic mobilities different ly. Equal but opposite electroosmotic and micellar electrophoretic vel ocities were obtained at a specific Brij 35 concentration, thereby pro ducing a ''stationary'' micellar phase. Retention characteristics of a series of n-alkylphenone homologues suggested a nearly infinite eluti on range. Infinite elution ranges are possible at neutral pH (7.0) usi ng deactivated fused-silica capillaries and at a pH of 6.2 using untre ated fused-silica capillaries,