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Despite good development in modern analytical instruments, direct determination of trace analytes at low concentrations is often a problem for analytical chemists and, as a result, a sample-preparation step is required. The sample preparation in analytical process typically consists of an extraction–separation step, which offers not only the ability to isolate target analytes from the matrix solution, thus reducing or even eliminating originally present interferences but also the opportunity for these analytes to be preconcentrated and determined at very low levels. Liquid–liquid extraction (LLE), based on the partitioning of an analyte from one liquid phase to another immiscible liquid phase, is a still widely used traditional sample preparation technique. However, this method is time-consuming and tedious. Also large amounts of high purity solvents, which are expensive and toxic, are inevitable to be used. The continuous quest for novel sample preparation procedures has led to a development of new methods, which have main advantages like rapidity and reduction of solvents consumption, such as cloud point extraction (CPE), solid-phase microextraction (SPME), single drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid–liquid microextraction (DLLME) and others. Cloud point extraction is considered to be a green extraction method because the extraction is performed while using surfactants, which may exhibit lower toxicity, volatility and flammability compared with organic solvents used in other extraction techniques. This technique is widely used in extraction of metals (Bezerra et al., 2005; Dallali et al., 2009), organic compounds (Carabias-Martinez et al., 2000) and proteins (Saitoh & Hinze, 1995). Despite many benefits when using CPE, in rather high content of salt, background is increased since the enrichment phase is composed of a little aqueous sample. Also in the presence of more than 3 % of water-miscible organic solvents such as acetone the phase separation does not occur and the extraction system is destroyed (Manzoori & Karim-

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Cold-Induced Aggregation Microextraction: A Novel Sample Preparation Technique Based on Ionic Liquids for Preconcentration of Cobalt Prior to Its Determination by Fiber Optic-Linear Array Detection Spectrophotometry in Real Water Samples