The cloud point procedure (CPE) procedure is based on the followingphenomenon: an aqueous solution of some surfactant becomes turbid andseparates into two isotropic phases if some condition such as temperature orpressure is changed or if an appropriate substance is added to the solution.The surfactant solution becomes turbid because it attains the cloud point. Atthis point, the original surfactant solution separates into a surfactant phaseof small volume, which is rich in the surfactant and containing the analyteor metal (organic or inorganic species) trapped by micellar structures and abulk diluted aqueous phase