Flow injection analysis of copper diethyldithiocarbamate in high resistance toluene media using a microelectrode detector

Flow injection (FI) analysis of copper as the copper diethylthiocarbamate complex (Cu(Et₂dtc)₂) has been performed in a high resistance toluene carrier stream. The method is based on the oxidation of the copper complex at a platinum microelectrode fabricated to fit a Metrohm wall-jet flow cell. Electrodes of sizes 5 to 25 μm radii were tested in toluene-based carriers containing either 0.03 M tetrahexylammonium perchlorate (Hex₄NClO₄) or 35% acetonitrile. Detection limits (3 : 1 signal to noise ratio) in the range 1 × 10⁻⁷ M (5 μm radius electrode) to 5 × 10⁻⁸ M (25 μm radius electrode) were achieved, which are comparable to detection limits reported in lower resistance media under similar conditions. The system was applied to the analysis of copper in water samples after extraction of the metal as its diethyldithiocarbamate into toluene and good agreement was found with data obtained by other voltammetric methods.