A waste water sample from a jewelry factory was obtained from the Gem and Jewelry Institute of Thailand (Public Organization). The jewelry waste sample was prepared by filtration of 20 mL of waste water with Whatman No. 1 filter paper. Then the sample
was mixed with 20 mL of HNO3 and the solution was heated at 200 1C to evaporate the solvent. After that, the sample was made up with 20 mL of Milli-Q water and was heated at 100 1C until dryness (repeated three times). Next, the sample was rinsed withmixed solution between 20 mL of 0.1 M NaCl and Cu solution 4.5 ppm (pH 6.7). Finally, the sample was sonicated for 30 min and
clear solution was ready for analysis.