پديدآورندگان :
Davvaji asl Sina Environmental Science Research Laboratory, Department of Environmental Science, Faculty of Science, University of Zanjan, 45371-38791, Zanjan, Iran , Zamani Abbasali Zamani@znu.ac.ir Environmental Science Research Laboratory, Department of Environmental Science, Faculty of Science, University of Zanjan, 45371-38791, Zanjan, Iran; , Badiei Hamid Environmental Science Research Laboratory, Department of Environmental Science, Faculty of Science, University of Zanjan, 45371-38791, Zanjan, Iran; Department of Chemistry, Faculty of Science, University of Guilan, University of Campus 2, Rasht, Iran , Fashi Armin Environmental Science Research Laboratory, Department of Environmental Science, Faculty of Science, University of Zanjan, 45371-38791, Zanjan, Iran
كليدواژه :
Ammonia , Solvent stir , bar microextraction , Berthelot reaction , water samples
چكيده فارسي :
Ammonia is a significant micro-nutrient in aquatic ecosystems due to its role in the aquatic nitrogen cycle. Nevertheless, ammonia can induce eutrophication of aquatic system with the external discharge of domestic sewage, fertilizers and industrial wastewaters into water sources [1, 2]. Thus, it is considered as a toxic pollutant to fish and diatoms and other aquatic life. However, due to the presence of ammonia at trace concentrations, its analysis is a real challenge for evaluating of biological study in aquatic ecosystems [3]. In this work, preconcentration-determination of ammonia in water samples was performed by combination of surfactant-enhanced two phase solvent stir-bar microextraction (SSBME) and microcell UV–Vis spectrophotometry. To develop this microextraction method, a short length of polypropylene hollow fiber was fixed on a magnetic rotor using a stainless steel wire and used as an extraction device for the preconcentration of ammonia (Fig.1). In this device, the hollow fiber moved along with the magnetic bar in sample solution under external magnetic field on a stirrer. Tetrabutylammonium bromide was added into the donor solution to form an ion-pair with indophenol blue achieved according to the Berthelot reaction. Then, the ion-pair was extracted from donor phase into the acceptor phase impregnated in the pores and lumen of the hollow fiber. Significant parameters affecting the proposed SSBME method such as type and concentration of cationic surfactant, type organic solvent, effect of extraction time, sample volume, ionic strength and stirring rate, were studied and optimized to obtain the maximum preconcentration factor. Under the optimized conditions the proposed SSBME method provided good linearity (1–500 ng mL−1), acceptable relative standard deviations (RSDs 7 %) with preconcentration factor of 200 fold. Finally, the proposed method was successfully applied to monitor trace amounts of ammonia in real sample waters.
