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

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 degrees 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.