Determination of metal ions complexed with 2,6-diacetylpyridine bis( N-methylenepyridiniohydrazone) by capillary electrophoresis

Abstract

Metal ions were determined quantitatively and selectively by complexation with 2,6-diacetylpyridine bis( N-methylenepyridiniohydrazone) (H 2dapmp) and separation of the metal ion complexes formed using capillary zone electrophoresis. The effect of various alkyltrimethylammonium ions added to the running electrolyte on the migration behaviour of cationic chelate complexes was examined. As a result, some evidence was obtained that both electrophoretic migration and micellar partitioning play the major role in the separation mechanism. Optimum resolution of metal-H 2dapmp complexes was achieved with a 10 mM sodium borate buffer (pH 9.0) containing 75 mM tetradecyltrimethylammonium bromide and 10 mM sodium n-octanesulfonate as an ion-pairing counterion. With this micellar buffer system, it was possible to separate and determine up to fourteen metal ions in a single run within 12 min using fused-silica capillaries at 15 kV and direct on-column UV detection at 254 nm. Linear calibration ranges of more than two orders of magnitude and detection limits at mid-ppb levels are presented for the metal complexes of Cd(II), Co(II), Cu(II), Fe(III), Hg(II), Mo(VI), Sc(III), U(VI), V(V), Y(III) and Zn(II).