RESUMEN
Cloud point extraction(CPE) utilizing a cationic surfactant, tricaprylmethylammonium chloride(Aliquat 336), was carried out to separate and concentrate bisphenol A(BPA) from aqueous media. Cloud point phase separation of Aliquat 336 at room temperature(about 25 ℃) was induced by the addition of Na_2SO_4. The parameters affecting extraction efficiency, such as concentrations of Aliquat-336 and Na_2SO_4, pH, and equilibration time were evaluated. The results showed that the extraction efficiency was practically constant in the studied range of Aliquat 336, co-solvent(methanol), pH and dissolved organic matters. At the operational CPE conditions, distribution constant, K_D, of the distribution of BPA between the surfactant-rich and aqueous phases of the CPE system was estimated to be 10~4. Coupled to liquid chromatography with UV detection, the CPE method offered a detection limit of 0.34 μg/L in distilled water and recovery of BPA ranged from 90% to 108.6% with a sample volume of 50 mL in three matrices studied. The high extraction efficiency might be due to combination of ion-pair, hydrophobic effects and cation-π interaction, based on the micelles' size distribution and zeta potential analysis.