Application Of Novel Liquid Phase Microextraction In The Separation And Preconcentration Of Trace Elements

As science and technology development, also produced a serious pollution problem. It is difficult to determine trace elements in the complex sample. So development of simple, rapid and effective analytical separation and preconcentration method is necessary.Dispersive liquid-liquid microextraction (DLLME) is a novel extraction techniques. In this method, an appropriate mixture of a few microliters of organic extraction solvent and a small volume of a dispersion solvent is injected rapidly into an aqueous sample, resulting in the formation of a stable emulsion. After centrifugation, the enriched analyte in the sediment phase is detection directly. This method has been rapid developed in the analysis of environmental, biological and food sample. Displacement dispersive liquid-liquid microextraction (DDLLME) and ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) are novel extraction techniques, which are based on DLLME. In the former, replacement method is used, improves the extraction of anti interference; in the latter, organic dispersive solvent is displaced by surfactant.In this study, new methods based on DLLME combined with graphite furnace atomic absorption spectrometry (GFAAS) were introduced for trace elements in environment.The major contents are described as follows:1. The pretreatment method of DDLLME combined with GFAAS was used for determination of trace mercury. In this extraction technique, DDTC was used as the complexing agent, CCl4was used as as extraction agent, methanol was used as dispersive solvent, respectively. Hg and Cu were difference complex stability with DDTC, Hg displacement Cu from Cu-DDTC. Using two independent DDLME to achieve selective extraction of Hg.The paper optimized the corresponding extraction factors, and determine the best extraction conditions. The operation conditions were applied to the determination of trace mercury in real samples.2. The pretreatment method of one step DDLLME combined with GFAAS was used for determination of trace methylmercury. In this extraction method, DDTC was used as the complexing agent, CCl4was used as extraction agent, methanol was was used as dispersive agent, respectively. This method simplified the DDLLME step, use only one step achieve extraction. The paper optimized the corresponding extraction factors, and determine the best extraction conditions. The operation conditions were applied to the determination of trace methylmercury in waters samples with satisfactory results.3. In this extraction technique, SDS instead of dispersive agent, DDTC was used as the complexing agent, CHCl3was used as extraction agent, UASEME combined with GFAAS for determination of trace cobalt in waters samples with satisfactory results.