Separation of palladium(II) and platinum(II) as their dithiosemicarbazone chelates by reversed-phase HPLC.

Abstract

The complex formation of palladium(II) and platinum(II) with glyoxal bis(4-phenyl-3-thiosemicarbazone) (GBS), methylglyoxal bis(4-phenyl-3-thiosemicarbazone) (MBS), dimethylglyoxal bis(4-phenyl-3-thiosemicarbazone) (DMBS) and methylethylglyoxal bis(4-phenyl-3-thiosemicarbazone) (MEBS) were studied in 80 v/v% N, N-dimethyl-formamide-water mixture. And reversed-phase HPLC with a spectrophotomertric de-tection was applied to the separation of their Pd-and Pt-chelates by using an ODS col-umn (6 mm i.d.×250 mm in length). Palladium(II) and platinum(II) formed stable chelates with each reagent in weak acidic medium, though it needed to be heated at 80°C for 15 min on the formation of Pt-chelate. The elution peaks of Pd and Pt-chelates on their chromatogram were not successfully separated by using methanol-water and acetonitrile-water as mobile phases. The resolved separation of Pd- and Pt-chelates were achieved by using an acetone-water mobile phase. The Pt-chelates were eluted more rapidly than the Pd-chelates in all reagent systems. In both metal systems, the retention time of each metal chelate was longer in order of GBS, MBS, DMBS and MEBS. The linear relationship was found between the logarithms of capacity factor (log k') of Pdand Pt-chelates and all alkyl carbon number of glyoxal residue in dithiosemicarbazone compounds.