| Some sensitive, rapid, reproducible, simple and accurate analytical methods are required for the determination of trace analyte in different samples. The direct determination of low concentrations of trace analyte was often difficult not only with the insufficient sensitivity of these techniques but also with matrix interference. For this reason, the separation and preconcentration of trace analyte often required.Ionic liquid liquid-liquid extraction is a novel technique integrating extraction, concentration and into one step. It has become widely used in analytical chemistry for overcoming the shortcomings of traditional sample preparation technique in time-consuming, tedious, multistage operation and organic solvent consumption. The ionic liquid liquid-liquid extraction system has many merits of excellent of diverse operation modes and easily being coupled with a variety of analytical instruments.The objective of this work aims to develop new methods with the ionic liquid liquid-liquid extraction combinated with atomic spectroscopy and high performance chromatography. The major contents are summarized as follows:(1)A new simplified extraction of room-temperature ionic liquid(RTIL) for trace Au(Ⅲ) as a prior step to its determination by flame atomic absorption spectrometry has been developed, which is based on the extraction of Au(Ⅲ) in RTIL 1-butyl-3-methylimidazolium hexafluorophosphate without a chelating agent. The parameters of extraction system were investigated in detail. At optimum conditions, the linear range of 0.19-38.20 μg·mL-1 of Au(Ⅲ), the limit of detection 0.072 μg·mL-1 for Au(Ⅲ) along with enrichment factors of 10.0 and the extraction capacity of 6.6 mg·g-1 by 1-butyl-3-methylimidazolium hexafluorophosphate for Au(Ⅲ) were obtained. The extraction mechanism and the selectivity of Au(Ⅲ) with 1-butyl-3-methylimidazolium hexafluorophosphate was also discussed. The proposed method was applied to extract trace amounts of Au(Ⅲ) in water samples with satisfactory results.(2) A rapid and effective method of aqueous two-phase systems based on ionic liquid microextraction for the simultaneous determination of five synthetic food colorants(tartrazine, sunset yellow, amaranth, ponceau 4R and brilliant blue) in food samples was established. High-performance liquid chromatography coupled with an ultraviolet detector of variable wavelength was used for the determinations, 1-alkyl-3-methylimidazolium bromide was selected as the extraction reagent. The extraction efficiency of the five colorants in the proposed system is influenced by the types of salts, concentrations of salt and [CnMIM]Br, as well as the extracting time. Under the optimal conditions, the extraction efficiencies for these five colorants were above 95%. The phase behaviors of aqueous two-phase system and extraction mechanism were investigated by UV-Vis spectroscopy. This method was applied to the analysis of the five colorants in real food samples with the detection limit of 0.051-0.074 ng/mL, the relative standard deviation(RSD) of 3.8% and 4.6%(n=5, c=5.0×102 ng/mL) respectively. Good spiked recoveries from 93.2-98.9% were obtained.(3) A rapid and effective method of aqueous two-phase systems based on ionic liquid microextraction for the simultaneous determination of puerarin in human plasma was established. High-performance liquid chromatography coupled with an ultraviolet detector of variable wavelength was used for the determinations. 1-Ethyl-3-methylimidazolium ethyl sulfate was selected as the extraction reagent. The extraction efficiency of the puerarin in the proposed system is influenced by the types of salts, concentrations of salt and ionic liquid, as well as the extracting time. Under the optimal conditions, the calibration curve of puerarin was linear in the range of 2.5-1.0×102 ng/mL with the LOD of 0.51ng/mL and the relative standard deviation(RSD) was 2.4%(n=5, c=25.0 ng/mL). The phase behavior of aqueous two-phase system was investigated by UV-Vis spectroscopy. This method was applied to the analysis of puerarin in human plasma with satisfactory results.(4) A rapid in situ ionic liquid-dispersive liquid-liquid microextraction system was first developed for the extraction of basic yellow I and basic yellow Ⅱ in the yellow croaker. By adding an ion-exchange reagent NH4PF6 to the hydrophilic ionic liquid [CnMIM]Br aqueous solution, an in situ halide exchange reaction proceeded to form a hydrophobic ionic liquid [CnMIM]PF6. The influence of several effects on the extraction were investigated, including pH, the type of ionic liquid, the concentration of [CnMIM]Br and NH4PF6, shaking time, centrifugation time and etc. Under the optimal conditions, the calibration curve of basic yellow I and basic yllow Ⅱ were linear in the range of 1.6-1.0×103 ng/mL and 2.8-1.0×103 ng/mL with the LOD of 0.28 ng/mL and 0.56 ng/mL respectively (n=5, c=10.0 ng/mL). The in situ ionic liquid dispersive liquid-liquid microextraction system was appled to the determination of basic yellow I and basic yellow II in the yellow croaker with satisfactory results. The recoveries for the spiked samples were in the range of 93.3-106.4% and 92.5-105.0%. |
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