Present thesis has been focused on two fields: 1) synthesis of magnetic nanostructure sorbents for development of magnetic solid phase extraction, and 2) preparation of new sorbents for solid phase microextraction. In the first study, a facile and simple method was developed for the modification of magnetic nanoparticles (M) surface with phenyl-functionalized silica. The nanoparticles were used for the extraction of 1,4-dichlorobenzene (1,4-DCB), 1,2,3-trichlorobenzene (1,2,3-TCB), 1,2,4-trichlorobenzene (1,2,4-TCB), and 1,2,3,4-tetrachlorobenzene (1,2,3,4-TeCB) from water, followed by their determination by gas chromatography-electron capture detector (GC-ECD). Different parameters influencing the performance of the extraction such as type and volume of desorption solvent, ionic strength, sorbent amount, and temperature and time of extraction were investigated. Under optimal conditions, enrichment factors ranging from 220 to 360 were obtained. Limit of detections (LODs) were in the range of 6 to 500 ng/L. relative standard deviation (RSDs) were found to be between 3.5 and 5.8%. The method was successfully applied to the determination of CBs in environmental water samples. In the second study, a new method based on coating of magnetic nanoparticles surface with surfactants was evaluated. The sorbent was employed for preconcentration of bromate from aqueous samples. After extraction, bromate was converted to bromine by sodium metabisulfite, and then the bromine was reacted with reduced fuchsin to form bromurated red coloured product. Finally, a column-less HPLC system with a UV–Vis spectrophotometric detector was applied as a simple and fast quantitative method for the determination of the coloured product. The effects of surfactant and amount of sorbent, the composition of the desorption solution; the extraction time and temperature were optimized. Under optimized conditions, enrichment factor, LOD and RSD were 12, 0.5 µg/L and 2.9% respectively. The method was not interfered by ionic compounds commonly found in the environmental water samples. It was successfully applied to the determination of bromate in spiked water samples including tap water, river water and well water. In the third study, a carbon coated fiber was constructed using of electrospinning method and applied as a new sorbent for solid phase microextraction. The fiber was then applied for the preconcentration and determination of chlorobenzenes in water samples. GC-ECD was utilized for separation and determination of the target compounds. Various factors which influenced the extraction and desorption of the analytes (condition the temperature of the fiber, salt concentration, extraction temperature and time, and desorption temperature and time) were investigated. LOD values were between 14 and 350 ng/L and RSDs were from 4.7 to 14.2%. The fiber showed better extraction efficiency than the commercial SPME fiber (PDMS). Finally, the new SPME fiber was applied for environmental sample analysis. In the final work, oxygenated activated carbon cloth was introduced for thin film microextraction. Phenylurea herbicides as model compounds were extracted using the sorbent. High-performance liquid chromatography with UV–Vis diode array detector (HPLC-DAD) was used for the analysis of extracted compounds. Conditions affecting the extraction and desorption were optimized. Under optimal conditions, LODs ranged from 0.04 to 0.11 µg/L. The RSD of the method varied from 4.4 to 12.1%. Capability of the method for real sample analysis was investigated by analysis of tap, well and river water samples.