MIGRATION BEHAVIOR OF INORGANIC ANIONS IN MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY USING A CATIONIC SURFACTANT

The interactions between inorganic anions and a cationic surfactant we re investigated using micellar electrokinetic capillary chromatography (MECC). Using cetyltrimethylammonium chloride (CTAC) as a cationic su rfactant, the effective electrophoretic mobilities of inorganic anions decreased due to two processes. The first was the ion association equ ilibria with a monomeric surfactant below the critical micellar concen tration (cmc) and the other was partitioning into the micelle above th e cmc. Fundamental equations for migration of ionic species in MECC we re derived using the effective electrophoretic mobility as an electroc hemical parameter. Ion association constants of inorganic anions with cationic surfactant and distribution coefficients into the micelle wer e estimated on the basis of these equations.