Effect of solvent and temperature on extraction of polychlorinated biphenyls and polychlorinated dibenzodioxins from fly ash

The effect of solvent and temperature on the extraction of two polychlorina ted biphenyls (PCBs) and five polychlorinated dibenzodioxins (PCDDs) from f ly ash is investigated and the variations in recoveries of these analytes a re explained. The extraction is performed using chromatographic elution, ul trasound-assisted extraction (UAE), enhanced-fluidity liquid extraction (EF LE), and pressurized fluid extraction (PFE). In each of the extraction meth ods used, only the use of isopropanol-toluene mixtures (5:95 or 10:90, v/v) shows higher recoveries than the use of toluene alone. Applied temperature is an important factor for the higher recoveries throughout all the extrac tion methods. After each extraction, chromatographic interferences are remo ved through a multilayer silica gel column clean-up. The quantification of PCBs and PCDDs is performed using HPLC-UV.