HYDROPHOBIC SALT-INDUCED PHASE-SEPARATION AND EXTRACTION FOR SAMPLE PREPARATION IN CHROMATOGRAPHIC DETERMINATION OF HEAVY-METAL IONS AS DIBENZYLDITHIOCARBAMATES

The dibenzyldithiocarbamate complexes with cadmium(II), nickel(II), me rcury(II), copper(II) and cobalt(II) were extracted into an acetonitri le phase from aqueous media by adding tetrabutylammonium perchlorate a s a phase-separation agent. The salt-induced phase-separation was used for the reversed-phase liquid chromatographic (LC) determination of t hese metal ions following direct injections of the acetonitrile extrac t onto a C-18 column. The mobile phase was a mixture of 4:1 (v/v) acet onitrile-0.02M acetate buffer (pH 4.4). Detection limits for the metal ions were in the range of the ng/ml concentration levels of the origi nal aqueous solution. Analysis of standard biological samples (tea and citrus leaves) could be made to evaluate the present LC method. (C) 1 997 Elsevier Science B.V.