An Acid-Induced Phase Cloud Point Separation Approach Using Anionic Surfactants for the Extraction and Preconcentration of Organic Compounds

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• 作者：I. Casero ; D. Sicilia ; S. Rubio ; and D. Pé ; rez-Bendito
• 刊名：Analytical Chemistry
• 出版年：1999
• 出版时间：October 15, 1999
• 年：1999
• 卷：71
• 期：20
• 页码：4519 - 4526
• 全文大小：74K
• 年卷期：v.71,no.20(October 15, 1999)
• ISSN：1520-6882

文摘

The acid-induced liquid-liquid phase separation of anionic surfactants in aqueous solutions, and its applicability to cloud point extraction methodology, were examined.The phase diagrams obtained (e.g., [HCl] vs [surfactant])consisted of three regions: a homogeneous liquid region,two coexisting isotropic phases, and a solid region. Thebreadth of each region was found to depend on thesurfactant structure. The behavior of each phase was alsoexamined in relation to temperature and added salts. Theanionic surfactants investigated were sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonic acid (SDBSA), sodium dodecanesulfonic acid (SDSA), and sodiumdioctylsulfosuccinate (Aerosol OT). The use of anionicsurfactant-mediated phase separations provided very highextraction efficiencies (80-100%) for pyrene in aqueoussamples and various PAHs in a certified reference material (dried sewage sludge). The preconcentration factorachieved was found to be a function of both surfactant andacid concentrations. Theoretical preconcentration factorsas high as 230 can be reached with Aerosol OT. Alkylsurfactants were used to preconcentrate polar PAHs andprogesterone prior to their determination by HPLC. Thelack of an aromatic moiety in the structure of the surfactants and their ionic character enables complete resolution of their chromatographic peak from those of theanalytes. The ability of anionic surfactants to extractthermally labile compounds was confirmed by extractingvitamin E at 10 C with recoveries of about 80-85%.