Automatic determination of copper by in-syringe dispersive liquid-liquid microextraction of its bathocuproine-complex using long path-length spectrophotometric detection

The recently proposed concept of automatic in-syringe dispersive liquid-liquid microextraction was successfully applied to the determination of copper in environmental water samples. Bathocuproine was added to the organic phase as a selective reagent, resulting in the formation of a complex with copper. Dispersion was achieved by aspiration of the organic phase and then the watery phase into the syringe as rapidly as possible. After aggregation of the solvent droplets at the head of the syringe, the organic phase was pushed into a liquid waveguide capillary cell for highly sensitive spectrophotometric detection. The entire analytical procedure was carried out automatically on a multisyringe flow-injection analysis platform and a copper determination was accomplished in less than 220 s. A limit of detection of 5 nmol L^-1 was achieved at an extraction efficiency >90% and a preconcentration factor of 30. A linear working range for concentrations of up to 500 nmol L ^-1 and an average standard deviation of 7% in peak height were found. The method proved to be well-suited for the determination of copper in water samples, with an average analyte recovery of 100.6%.