Capillary zone electrophoretic and micellar electrokinetic capillary chromatographic separations of polyaminopolycarboxylic acids as their copper complexes

Capillary zone electrophoretic (CZE) and micellar electrokinetic capillary chromatographic (MECC) separations with UV absorbance detection at 290 nm were developed for separation and detection of the negatively-charged copper complexes of the polyaminopolycarboxylic acids. A standard mixture that contained ethylenediaminetetraacetic (EDTA), nitrilotriacetic (NTA), ethylenediaminetriacetic (ED3A), diethylenetriaminepentaacetic (DTPA) and hydroxyethylenediaminetriacetic (HEDTA) acids was utilized to demonstrate these separation methods. MECC techniques were performed with either cationic (cetyltrimethylammonium bromide, CTAB) or anionic (sodium dodecyl sulfate, SDS) surfactants. All three separation techniques achieved separation of the standard components with baseline resolution. A fast separation (7.5 min) was obtained with CTAB surfactant that provided a detection limit of 38 pg for HEDTA. The cationic micellar strategy was also extended to separations of mixed-metal EDTA complexes.