The solvent extraction of trace metals in seawater has been investigated in order to improve the method by collating the good points of every procedures of solvent extraction proposed for the analysis of seawater. The APDC-MIBK Extraction System followed by back extraction with nitric acid is chosen for this study. It is found that the optimized conditions for first extraction of Cu, Ni, Pb and Zn in 100 ml treated seawater sample are as follows : the concentration of APDC is 5 ml 2% (w/v), the volume of organic solvent, MIBK, is 5 ml and shaking time for the first extraction is 4 min. The optimium pH of seawater is in the range 4-6 which should be adjusted prior to the addition of APDC and MIBK. For the back extraction, 5 ml of 4N nitric acid is used and shaking time for the back extraction is 5 min.
