Acid-induced cloud point extraction

For fluorescence PAH determination in tap water acid-induced cloud point extraction was used. This kind of extraction based on the phase separation into two isotropic liquid phases a concentrated phase containing most of the surfactant (surfactant-rich phase), where the solubilised solutes are exttacted, and an aqueous phase containing a surfactant concenttation closes to the critical micellar concentration. 

The aqueous micellai solutions of some surfactants exhibit the cloud point, or turbidity, phenomenon when the solution is heated or cooled above or below a certain temperature. Then the phase sepai ation into two isotropic liquid phases occurs a concentrated phase containing most of the surfactant and an aqueous phase containing a surfactant concentration close to the critical micellar concentration. The anionic surfactant solutions show this phenomenon in acid media without any temperature modifications. The aim of the present work is to explore the analytical possibilities of acid-induced cloud point extraction in the extraction and preconcentration of polycyclic ai omatic hydrocai bons (PAHs) from water solutions. The combination of extraction, preconcentration and luminescence detection of PAHs in one step under their trace determination in objects mentioned allows to exclude the use of lai ge volumes of expensive, high-purity and toxic organic solvents and replace the known time and solvent consuming procedures by more simple and convenient methods. 

Sodium dodecylsulphate was selected as an anionic surfactant Factors affecting acid-induced cloud point extraction including surfactant, hydrochloric acid, PAHs, and electrolyte concentration, centrifugation have been examined. Finally, we applied the optimized acid-induced CPE system for combination of the extraction and preconcentration steps with fluorimetric determination of some representatives of PAHs. Suggested means was used for PAHs determination in tap water. 

Merino, F., Rubio, S., and Perez-Benito, D., Acid-induced cloud point extraction and preconcentration of polycyclic aromatic hydrocarbons from environmental solid samples, J. Chromatogr. A, 962, 1-8, 2002. 

Meeravali, N.N., Kumar, S.J., Jiang, S.J. An acid induced mixed-micelle mediated cloud point extraction for the separation and pre-concentration of platinum from road dust and determination by inductively coupled plasma mass spectrometry. Anal. Methods 2, 1101-1105 (2010)... 

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