3.2.3. Effect of pH
In the extraction of metal ions, the extraction efficiencies of metal complex are closely related to the pH of the system. The separation of metal ions by SDME involves prior formation of a complex with sufficient hydrophobicity to be extracted into the small volume of the sedimented phase. In the experiment, pH plays a unique role on metal-chelate formation and subsequent extrac-tion. In order to obtain the desired preconcentration efficiency, the pH values were studied in the range of 2.0–9.5 adjusted by