LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL AND OR SPECTROPHOTOMETRIC DETECTION FOR AUTOMATED-DETERMINATION OF LEAD, CADMIUM, MERCURY, COBALT, NICKEL, AND COPPER

In situ formation of dithiocarbamate complexes within a chromatographic system was investigated as a method for the simultaneous and automated determination of Pb, Cd, Hg, Co, Ni and Cu. The automated, microprocessor-based system developed for the multielement determination can be operated continuously for periods of several days with either spectrophotometric or electrochemical detection. Limits of detection of 1 ng/10 .mu.l injected were achieved with spectrophotometric detection. Addition of an ion exchange based suppressor column to remove excess dithiocarbamate ligand prior to detection improved spectrophotometric detection limits for Ni, Cu, Co and Hg, but is deleterious for determination of Pb and Cd and decreases the period of time over which the automated instrumentation can be run unattended. Electrochemical detection over extended periods of time employing oxidation at a glassy carbon electrode is considerably more sensitive for Ni and Cu than for the other elements. [Pb, Hg and Cd are among the most toxic metals known to man.].