DETERMINATION OF CU(II) AND NI(II) AS CHELATES WITH BUTYL XANTHATE BYLIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL AND SPECTROPHOTOMETRIC DETECTION

Butyl xanthate (EX) has been examined for the separation of Cu(II), Ni (II), Pb(II), Hg(II) and Cd(II) chelates by reversed-phase liquid chro matography using a C-18 column. The chelates are well separated with 7 :3 (v/v) acetonitrile-sodium acetate (0.02 M, pH 7.8) containing 2 X 1 0(-3) M EX and 0.02 M potassium nitrate. For electrochemical detection with a glassy carbon working electrode, the oxidation of excess ligan d in the mobile phase can be minimized by setting the potential at + 0 .20 V vs. Ag/AgCl whereby the detection limits of Cu(II) and Ni(II) ar e lowered to 0.10 and 0.22 mu g l(-1), respectively. Spectrophotometri c detection at 330 nm can also be used for the simultaneous determinat ion of the above five metal ions with good sensitivity. The method has been applied to the determination of Cu and Ni in industrial waste wa ter and biological samples.