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Mixed hemimicelles solid-phase extraction based on cetyltrimethylammonium bromide-coated nano-magnets Fe₃O₄ for the determination of chlorophenols in environmental water samples coupled with liquid chromatography/spectrophotometry detection

Li, Jidong, Zhao, Xiaoli, Shi, Yali, Cai, Yaqi, Mou, Shifen, Jiang, Guibin
Journal of chromatography 2008 v.1180 no.1-2 pp. 24-31
2,4-dichlorophenol, 2-chlorophenol, accuracy, adsorption, detection limit, iron oxides, liquid chromatography, magnetic separation, magnetism, nanoparticles, pH, pentachlorophenol, solid phase extraction, surface area, water analysis, zeta potential
Mixed hemimicelles solid-phase extraction (SPE) based on cetyltrimethylammonium bromide (CTAB)-coated nano-magnets Fe₃O₄ was investigated for the preconcentration of four chlorophenols (CPs) in environmental water samples prior to HPLC-spectrophotometry determination in this paper. By the rapid isolating (about 5min) of Fe₃O₄ nanoparticles (NPs) through placing a Nd-Fe-B strong magnet on the bottom of beaker, the time-consuming preconcentration process of loading large volume sample in conversional SPE method with a column can be avoided. The unique properties of Fe₃O₄ NPs such as high surface area and strong magnetism were utilized adequately in the SPE process. This novel separation method produced a high preconcentration rate and factor. A comprehensive study of the adsorption conditions such as the Fe₃O₄ NPs zeta-potential, CTAB added amounts, pH value, standing time and maximal extraction volume was also presented. Under optimized conditions, four analytes of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) were quantitatively extracted. The method was then used to determine four CPs in five real environmental water samples. High concentration factors (700) were achieved for each of the analytes, with observed detection limits ranging between 0.11 and 0.15μgL-¹. The accuracy of method was evaluated by recovery measurements on spiked samples. Good recovery results (83-98%) with satisfactory relative standard deviation (RSD) were achieved. It is important to note that satisfactory preconcentration factors and extraction recoveries for the four CPs were obtained with only a little amount of Fe₃O₄ NPs (0.1g) and CTAB (60mg). To the best of our knowledge, this was the first time a mixed hemimicelles SPE method based on Fe₃O₄ NPs magnetic separation had been used for the pretreatment of environmental water samples.