Separation of dithiocarbamate metal complexes by micellar electrokinetic chromatography

Separation of a number of transition metal complexes with bis(2-hydroxyethy l)dithiocarbamate (HEDTC) by micellar electrokinetic capillary chromatograp hy (MEKC) with direct photometric detection was investigated. Pre-capillary complexation was shown to be superior to on-capillary complexation in term s of the number of metals ions which could be detected and their peak shape s, enabling analysis of Cd(II), Pb(II), Pt(II), Co(II), Ni(II), Bi(III), Cr (II), Cu(II) and Hg(II). The type and composition of the background electro lyte (BGE) were investigated with respect to separation selectivity and BGE stability. A BGE of 60 mM 3-(morpholino)propane sulfonic acid (MOPS), 30 m M tris(hydroxymethyl)aminomethane (Tris), 10 mM sodium dodecyl sulphate (SD S) and 100 mu M HEDTC, pH 7.2 was found to be optimal with nine metals base line separated in less than seven minutes, and giving separation efficienci es of up to 367 000 theoretical plates, reproducibility of corrected peak a reas below 3% relative standard deviation, concentration detection limits f rom 0.04 to 1.3 mu M and mass detection limits at sub femtomole levels (det ection at 254 nm).