Liquid chromatography of metal chelates. Chromatographic studies of homologous dialkyldithiocarbamates Original Research Article

The chromatographic behaviour of a selected group of metal dithiocarbamates was investigated by reversed-phase, liquid chromatography. Ligands with the general formula R2NCSSNa, where R is CH3CH2–, CH3CH2CH2–, (CH3)2CH–, CH3CH2CH2CH2– or CH3CH2CH2CH2CH2– were synthesised and used to prepare the corresponding complexes of zinc(II), arsenic(III), iron(III), cadmium(II), lead(II), nickel(II), copper(II), mercury(II), cobalt(III) and chromium(III). The chromatographic behaviour of the metal complexes on a C18 column was examined with the mobile phases comprising methanol–water, acetonitrile–water and methanol–acetonitrile–water. With the exception of one ligand [where R=(CH3)2CH–], the majority of the chelates were resolved satisfactorily. Although the Cd(II) and Pb(II) complexes were not resolved by the binary solvent systems, those derived from the straight-chain, higher homologues (C3–C5) were successfully separated with ternary solvent mixtures. Chelates of Zn(II), Fe(III) and the diethyldithiocarbamate of As(III) were not observed using any of these mobile phases.