Determination of Cu(II) and Ni(II) as chelates with butyl xanthate by liquid chromatography with electrochemical and spectrophotometric detection

Butyl xanthate (BX) has been examined for the separation of Cu(II), Ni(II), Pb(II), Hg(II) and Cd(II) chelates by reversed-phase liquid chromatography using a C18 column. The chelates are well separated with 7:3 (vv) acetonitrilesodium acetate (0.02 M, pH 7.8) containing 2 × 10−3 M BX and 0.02 M potassium nitrate. For electrochemical detection with a glassy carbon working electrode, the oxidation of excess ligand in the mobile phase can be minimized by setting the potential at +0.20 V vs. AgAgCl whereby the detection limits of Cu(II) and Ni(II) are lowered to 0.10 and 0.22 μg l−1, respectively. Spectrophotometric detection at 330 nm can also be used for the simultaneous determination of the above five metal ions with good sensitivity. The method has been applied to the determination of Cu and Ni in industrial waste water and biological samples.