Determination of Cd, Pb, Cu, Ni and Mn in effluents and natural waters by a novel salt induced mixed-micelle cloud point extraction using ETAAS

Abstract

A novel salt induced low temperature mixed-micelle cloud point extraction procedure is developed for simultaneous separation and pre-concentration of Cd, Pb, Cu, Mn and Ni from industrial effluents and natural water matrices. Electrothermal atomic absorption spectrometry has been used for their determination. The mixed-micelles are formed by micelle–micelle interaction of Triton X-114 and sodium dodecyl sulfate (SDS) micelles. These mixed aggregates have a strong hydrophobic core, due to strong packing of both hydrophobic cores of Triton X-114 and SDS micelles, which is further enhanced by the addition of an electrolyte. These enhanced hydrophobic solubilising sites are used for efficient extraction of ammonium pyrrolidine dithiocarbamate (APDC) metal chelates at temperatures of 25–5 °C. This low temperature extraction avoids the thermal decomposition of these thermally labile complexes. The parameters affecting the extraction procedures are optimized. Under the optimized conditions, a pre-concentration factor of 10 was obtained with limits of detection of 5, 80, 30, 50 and 10 pg mL⁻¹, respectively for Cd, Pb, Cu, Ni and Mn. The recoveries are in the range of 95–102% with 2–5% relative standard deviation. The accuracy of the procedure is evaluated by analyzing various certified reference materials such as BCR-713 final effluent, BCR-715 industrial effluent, BCR-609 ground water and NIST-1640a natural water matrices and also applied to real samples.