The acid-induced liquid-liquid
phase se
paration of anionic surfactants in aqueous solutions, and its a
pplicability 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 isotro
pic
phases, and a solid region. Thebreadth of each region was found to de
pend on thesurfactant structure. The behavior of each
phase was alsoexamined in relation to tem
perature 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 se
parations
provided very highextraction efficiencies (80-100%) for
pyrene in aqueoussam
ples 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 and
progesterone
prior to their determination by HPLC. Thelack of an aromatic moiety in the structure of the surfactants and their ionic character enables com
plete resolution of their chromatogra
phic
peak from those of theanalytes. The ability of anionic surfactants to extractthermally labile com
pounds was confirmed by extractingvitamin E at 10
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C with recoveries of about 80-85%.