Present thesis has been focused on dispersive liquid–liquid microextraction (DLLME) and synthesis of the magnetic composites for application in dispersive micro-solid phase extraction (D-?-SPE). In the first study, Trace analysis of chlorophenols (4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) in water was performed by simultaneous silylation and DLLME followed by gas chromatography with mass spectrometry. DLLME was carried out using an extraction solvent lighter than water ( n -hexane), acetone as disperser solvent and N , O -bis(trimethylsilyl)trifluoroacetamide as derivatization reagent. Under the optimum conditions, the calibration graphs were linear in the range of 0.05–50 ng/mL and the limit of detection (LOD) was 0.01 ng/mL. Besides, the method was applied for the analysis of real samples. In the second study, three modes of DLLME using organic solvent and ionic liquids (ILs) as extractant, were compared for extraction of three groups of compounds with various functionalities. For the analytes with polar functionalities, mostly better results were obtained by ILs. By contrast for hydrocarbons without polar functionalities extraction by chloroform led to better results. In these cases which, dispersion force was the main intermolecular interaction, refractive index of solvent and analyte was more appropriate parameter to predict extraction performance than K ow . It was also revealed that DLLME solely is not successful for extraction of very hydrophilic analytes. In the third study, the possibility of use of liquid anion exchangers in DLLME for the direct extraction of inorganic anions (nitrite, bromide, nitrate and iodide) was evaluated. In this technique, chloroform containing a liquid anion exchanger (trioctylamine) and acetone were used as extractant and disperser solvent, respectively and the analytes were determined by HPLC with UV-Vis detection. Under the optimum conditions, enrichment factors between 94 and 244 were obtained and LODs were in the range of 0.1-0.6 ng/mL. Finally, the proposed method was applied for the analysis of river, tap, spring and mineral water samples. In the fourth study, a composite of Fe 2 CoO 4 magnetic nanoparticles and polystyrene was synthetized by a simple, fast and one-step method and employed as sorbent in D-?-SPE format for extraction of parabens (methylparaben, ethylparaben, propylparaben and butylparaben) from water samples. Analytes detection was performed by LC-MS/MS. In this study, polystyrene trays, previously used for food packaging, was employed as polymeric source for the synthesis of magnetic composites. Under the optimum conditions, LODs were in the range of 0.05-0.15 ng/mL. River water, creek water and tap water samples were used for the evaluation of the method and the relative recoveries were calculated for these samples. In the fifth study, porosity improvement of magnetic polyamide composite by a simple method is offered in order to manufacturing high-efficiency D-?-SPE sorbent. Incorporation of a secondary polymer (polyethylene imine) to polymeric network and then removal of that, resulted to creation of spaces in the polymeric network and its porosity enhancement. The extraction capability of the sorbent was evaluated by determining six benzophenones in water using UPLC-PDA. Under the optimum conditions, LODs were obtained in the range of 0.5-4.3 ng/mL and relative standard deviations were in the range of 1.7-5.6%. Furthermore, the method applicability was investigated by the analysis of real samples.