Homogeneous liquid-liquid extraction for preconcentration of polycyclic aromatic hydrocarbons using a water/methanol/chloroform ternary component system.

A fast and effective preconcentration method for the extraction of polycyclic aromatic hydrocarbons (PAHs) was developed using a homogeneous liquid-liquid extraction based on phase separation phenomenon in a ternary solvent (water/methanol/chloroform) system. The phase separation phenomenon occurred by salt addition. After centrifugation, the extracting solvent was sedimented in the bottom of the conical test tube. The PAHs were transferred into the sedimented phase during the phase separation step. The extracted PAHs were determined using gas chromatography-flame ionization detection. Several factors influencing the extraction efficiency were investigated and optimized. Optimal results were obtained at the following conditions: volume of the consolute solvent (methanol), 1.2 mL; volume of the extracting solvent (chloroform), 60 muL; volume of the sample, 2.5 mL; concentration of NaCl, 15% (w/v). Under the optimum conditions, the enrichment factors of 225-257, the extraction percent of 90-100%, the dynamic linear range of 0.1-400 microg L(-1), and the limits of detection of 0.02-0.18 microg L(-1) were obtained for the PAHs. Using internal standard, the relative standard deviations for 100 microg L(-1) of the PAHs in the water samples were obtained in the range of 4.2-10.3% (n=5). Finally, the proposed method was successfully applied for the extraction and determination of the PAHs in waste water samples.