| Mercury widely exists in nature in a variety of forms, including elemental mercury, organomercury and inorganic mercury. It is well known that the environmental and ecological toxicological effects, bioavailability, mobility, persistence and other relevent aspects of mercury are highly dependent on its chemical form. Generally organomercury compounds are more toxic than inorganic mercury species, especially MeHg+being the most hazardous one, which can accumulate in superior organisms through the food chain. Therefore, mercury speciation is of great importance. However, because of mercury species in environmental water samples presents at a very low concentration (especially organic mercury), so the speciation analysis of mercury is very difficult.Hg2+, MeHg+, EtHg+and PhHg+were selected as the representative form of mercury species in the environment. The aim of this work is to develop new, rapid, simple and highly efficient analytical methods for mercury speciation at trace level, using a combination of DLLME and SPE with HPLC-DAD or CVAAS. Some important parameters affecting the extraction efficiency were investigated to determine the best experimental conditions, and to assess the analytical performance of methods. New methods were successfully applied to the analysis of real water samples.1:A novel approach for preconcentration and speciation analysis of trace amount of mercury in water samples was proposed by dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography with diode array detection (HPLC-DAD). Mercury species (Hg2+, methylmercury (MeHg+) and phenylmercury (PhHg+)) were complexed with dithizone (DZ) to form hydrophobic chelates and then extracted into the fine drops of extraction solvent dispersed in the aqueous sample by dispersive solvent. After extraction, the sedimented phase was analyzed by HPLC-DAD. Some important parameters affecting the DLLME such as extraction solvent and dispersive solvent type and volume, concentration of dithizone solution, sample pH, extraction time and salt effect were investigated. Under the optimized conditions, the limits of detection for Hg2+, MeHg+and PhHg+were0.32,0.96and1.91μg L-1(S/N=3) respectively, and the relative standard deviation (RSD) was between4.1and7.3%(n=5). Three real water samples (tap water, river water and lake water) spiked with mercury species were detected by the developed method, and the relative recoveries obtained for Hg2+, MeHg+and PhHg+were89.6-101.3%,85.6-102.0%and81.3-97.6%, respectively. The sensitivity enhancement factor (SEF) obtained for mercury species was within106-114.2:A new method for the speciation analysis of mercury species in water samples was developed by ionic liquid based dispersive liquid-liquid micro extraction (DLLME) and sulfhydryl cotton fiber solid phase extraction coupled to high performance liquid chromatography (HPLC) and cold vapour atomic absorption spectrometry (CVAAS). Mercury species (ethylmercury (EtHg+), methylmercury (MeHg+) and phenylmercury (PhHg+)) were complexed with dithizone (DZ) to form hydrophobic chelates and then extracted into the fine drops of1,3-dibutylimidazolium hexafluorophosphate ([BBIM][PF6]) dispersed in the aqueous sample by dispersive solvent. After extraction, the mercury complexes were separated by HPLC, and adsorbed by SCF respectively and eluted with HCl2, then used KMnO4-HCl-H2SO4oxidation system to decompose organic mercury to Hg2+and SnCl2to reduce Hg2+to Hg0prior to CVAAS system detection. Under the optimized conditions, the limits of detection for MeHg+, EtHg+and PhHg+were0.18,0.24and0.31(μg L-1(S/N=3) respectively, and the relative standard deviation (RSD) was between3.2and5.8%(n=5). The calibration curves for MeHg+, EtHg+and PhHg+were linear in the ranges of0.6-10μg L-1with the correlation coefficients over the range of0.9987-0.9997. The method was successfully applied to the analysis of two real water samples (tap water and river water) spiked with mercury species, and the relative recoveries obtained for MeHg+, EtHg+and PhHg+were94.4-98.1%,87.5-100.2%and83.3-97.3%, respectively.3:Glass bead fixed load silica film was prepared by sol-gel method using TEOS as precursor. Through the proceduce:dip and dry repeatedly, calcination, pickling activation and dry, and then [HMIM][PF6] ionic liguid was immobilized in the solid phase of glass bead fixed load silica. This product is denoted by [HMIM][PF6]/SiO2glass bead. And the product was identified by infrared spectroscopy analysis.4:Based on the method of1and SPE material of3, a new method for the speciation analysis of mercury species in water samples was developed by [HMIM][PF6]/SiO2glass bead solid phase extraction (SPE) and ionic liquid based dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography (HPLC). Mercury species (ethylmercury (EtHg+), methylmercury (MeHg+) and phenylmercury (PhHg+)) were complexed with dithizone (DZ) to form hydrophobic chelates and then extracted. Some parameters affecting the SPE were investigated.Under the optimized conditions, the sensitivity enhancement factor (SEF) obtained for mercury species was within1062-923, the limits of detection for MeHg+, EtHg+and PhHg+were0.015,0.021and0.028μg L-1(S/N=3) respectively and the calibration curves for MeHg+, EtHg+and PhHg+were linear in the ranges of0.05/0.08-5μg L-1with the correlation coefficients over the range of0.9962-0.9989. The method was successfully applied to the analysis of two real water samples (tap water and river water) spiked with mercury species, and the relative recoveries obtained for MeHg+, EtHg+and PhHg+were95.5-100.5%,94.1-98.5%and88.7-98.0%, respectively. |
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