A new and selective capillary column coated with cationic diazacrown ether for separation of organic and inorganic anions by capillary electrophoresis

A new coated capillary has been introduced for capillary electrophoretic separation of anions by using a positively charged diazacrown ether with a 12‐membered ring. A positive charge spread over the inner capillary surface led to a substantial anodic electroosmotic flow (EOF) over the range of migrating buffer of pH 2–11. Under the optimum conditions of 25 m M phosphate buffer at pH 7, the diazacrown‐coated capillary showed a successful simultaneous separation of 7 inorganic anions and 13 aromatic anions (including positional isomers) in less than 15 min. The migration times of the sample anions and EOF marker for consecutive runs on a single column were highly reproducible, giving a relative standard deviation of 1%. Theoretical treatment of the migration behavior clearly demonstrated that ion association between the diazacrown and analyte anions is strongly dependent on the nature of the functional groups of anions ( e.g. , sulfonate groups > carboxyl groups) and the number of negative charges ( e.g. , trivalent anions > divalent anions > monovalent anions) on the analyte.