Determination of total phthalate esters in wastewaters by differential pulse polarography

A reliable procedure for the determination of total phthalate esters as phthalic acid in environmental samples is based on differential pulse polarography (d.p.p.). The phthalate esters are extracted from the sample water with hexane; concentrated sulphuric acid/hexane partitioning provides effective removal of organic interferences. The individual phthalate esters are hydrolyzed by refluxing with 10 M potassium hydroxide to phthalic acid, which is extracted with ethyl acetate followed by evaporation of the extract. This procedure gives recoveries of 83–90%. The residue is dissolved in 0.1 M acetic acid/0.1 M potassium chloride for d.p.p. The otpimal conditions for polarography are discussed. The calibration graphs are linear over the range 2 × 10^?6–1 × 10^?4 M and the detection limit for phthalic acid is 5 × 10^?7 M. The method was successfully applied to determine total phthalate esters over the range 0.3–30 μg l^?1 in crude and treated wastewaters.