STUDIES ON SOLVENT-EXTRACTION AND FLOTATION TECHNIQUE USING METAL-DITHIZONE COMPLEXES(II) - DETERMINATION OF TRACE-ELEMENTS IN WATER SAMPLES BY SOLVENT SUBLATION

The preconcentration and determination of trace elements in water samp les were studied by a solvent sublation utilizing dithizonate complexa tion. After metal dithizonates were formed, trace amounts of cadmium, cobalt, copper and lead were floated and extracted into small volume o f a water-immiscible organic solvent on the surface of sample solution and determined in the solvent directly by GF-AAS. Several experimenta l conditions as formation condition of metal-dithizonate complexes, pH of Solution, amount of dithizone, stirring time, the type and amount of surfactants, N-2 bubbling rate and so on were optimized for the com plete formation and effective notation of the complexes. And also four kinds of light solvents were compared each other to extract the float ed complexes, effectively. After the pH was adjusted to 4.0 with 5 M H NO3, 8.0 mL of 0.05% acetone solution of dithizone was added to 1.00 L water sample. The dithizonate complexes were notated and extracted in to the upper methyl isobutylketone (MIBK) layer by the addition of 2.0 mt 0.2% ethanolic sodium lauryl sulfate solution and with the aid of small nitrogen gas bubbles. And this solvent sublation method was appl ied to the analysis of real water samples and good results of more tha n 85% recoveries were obtained in spiked samples.