Dissolved organic matter and pH affect the extraction efficiency of PCBs from aqueous samples

The effect of DOM concentration and pH on the extraction efficiency of PCBs from an aqueous solution with methylene chloride has been investigated. The recovery experiments were performed using a PCBs commercial mixture (Fenchlor 54). All the experiments were conducted at constant ionic strength, buffering the pH of the aqueous samples with universal buffer. Commercial humic acid was used to simulate natural DOM. An experimental design approach was used to estimate the effect of the simultaneous variation of both humic acid and pH on the extraction recovery of PCBs. The data obtained confirmed the presence of strong interactions among humic acid and PCBs. The organic matter present in the sample may significantly affect the PCBs extraction and such an effect is strongly dependent on the pH. The maximum extraction recovery of PCBs is obtained at a value of pH around 9.