Some Applications Of Mixed Hemimicelles Solid-phase Extraction And Dispersive Solid-phase Extraction

In this paper,some disadvantages in the traditional solid phase extraction and dispersive solid-phase extraction have been conquered.In this thesis,the modification of solid phase extraction and dispersive solid-phase extraction was made,and was applied to real sample analysis.This thesis is divided into four chapters,the main contents are as follows:Chapter 1: This part made a summary about current situation of new materials in sorbents for solid phase extraction and the development of dispersive solid-phase extraction.Special emphasis was placed on mixed hemimicelles solid-phase extraction and dispersive solid-phase extraction with elution step free.At the same time,the background and purpose of the study as well as the basic content of this article were elaborated.Chapter 2: In this work,a mixed hemimicelle solid-phase extraction method based on Al₂O₃ nanoparticles coated with cetyltrimethyl ammonium bromide?CTAB?was applied for the preconcentration two estrogens prio to their determination with high-performance capillary electrophoresis.The key factors influencing the extraction efficiency,such as Al₂O₃ NPs dosage,extraction time,the type and volume of eluent,sample pH,were investigated and optimized.The optimum conditions of sample pretreatment were: 200 mL Al₂O₃NPs?3 mg/m L?,8 min of extraction time,eluent for methanol,volume of 400 mL,pH of the solution is 11.0.Detection limits obtained for BPA and NP were 0.02 and 0.01 mg/m L,respectively.Under the optimized conditions,the proposed method was then applied to the analysis of the two estrogens in water samples from three different sources,and the recoveries were in the range of 81.1%-106%.Relative standard deviations for intra-and inter-day precision were less than 2.9% and 2.3%,respectively.Based on the mixed hemimicelle solid-phase extraction combined with capillary electrophoresis detection method,the two kinds of estrogens in the real water samples were successfully tested.This proposed method simplifies the separation,and the use of CTAB as extraction medium reduces the consumption of organic solvents,which is environmentally friendly.Chapter 3: In this work,a new determination of vanadium was developed with digital colorimetry combined with dispersive solid-phase extraction with phenolphthalein as adsorbent.A comprehensive study on the adsorption conditions such as the concentration of hydrochloric acid,the usage of BPHA,extraction time,the effect of salt,the amount of extraction solvent and the influence of coexisting ions were optimized.The optimum conditions of sample pretreatments were: hydrochloric acid?3 mol/L?,BPHA chelating agent?12 mg/m L?300 mL,extraction time 1 min,no salt,phenolphthalein ethanol solution?5%?200 mL.The method detection limit was 0.058 mg/mL.Under the optimal experimental conditions,the V?V?in the three kinds of water samples and two kinds of soil samples were determined,the recoveries were in the range of 94.8% to 101.9%.This paper successfully applied dispersive solid-phase extraction method phenolphthalein as adsorbent and combined with digital colorimetric method to test the V?V?.In the proposed method analyte elution step,as needed in conventional sorbent-based extraction,was obviated.Besides the method was green,environmental protection,easy to operate,save time,and it was applicable to the field test.Chapter 4: A method for the determination of two kinds of quinone compounds in rhubard medicinal?Alone-emodin and Rhein?was developed with capillary electrophoresis combined with dispersive solid-phase extraction with phenolphthalein as adsorbent.The key factors affecting the extraction,such as the extraction time,the amount of adsorbent,the type and dosage of dispersants,centrifugal time and amount of HCl?3 mol/L?,were optimized.It is concluded that the optimum conditions of sample pretreatments were: extraction time for 1 min,sorbent,phenolphthalein,4%?W/V?,disperser solvent: ethanol,100 mL,centrifuged at 3000 rpm for 3 min,add 100 mL HCl?3 mol/L?.The limits of detection for the two kinds of quinone compounds were: 0.04 mg/m L?Aloe-emodin?,0.06 mg/m L?Rhein?.Under the optimal experimental conditions,the approach was applied to the determination of Aloe-emodin and Rhein from rhubarb medicinal herbs which prepared with three different methods.Good recoveries were in the range of 77.7% to 116.9%,relative standard deviations for intra-and inter-day precision were less than 2.9% and 3.7%,respectively.