Abstract: A method for the determination of extractable petroleum hydrocarbons (EPH) in wastewater, comprising liquid-liquid extraction, purification by florisil and gas chromatography determination, was developed. Sample preparation and analytical conditions were investigated and optimized, including sample extraction, purification and concentration of extracts, and operating parameters of gas chromatography. The results showed that the recovery rates of EPH reached 99.7%—100% during purification by activated florisil; the removal rates of polar non-hydrocarbon model compounds (methyl palmitate or methyl oleate) were in the range of 90.7%—100%; EPH recovery rates reached 90.3%—92.5% by 3-times acidic extraction followed by 3-time alkali extraction. The detection limit of this method was 15.2 μg/L, blank spike and matrix spike recoveries were 92.0% and 81.5%, respectively. A case study of testing a refinery effluent showed that the relative standard deviation (RSD) of determination was 4.1% (n=6).

Key words: wastewater, extractable petroleum hydrocarbons, liquid-liquid extraction, gas chromatography, purification by florisil