| The extraction and determination of contaminants in environmental samplesand volatile components in traditional Chinese medicine are very important inanalytical chemistry. Various analytical methods, such as gas chromatography, highperformance liquid chromatography, have been developed. However, because theconcentrations of the analytes in the complex matrix are low and the chemicalcompositions are rather complicated， it is necessary to develop pretreatmentprocedures for extraction and concentration of the analytes. Sample preparationbefore instrumental analysis is one of the most important and crucial steps. In somesense, the reliability of the analytical method depends on the quality of the samplepretreatment procedures. Some procedures for preparing samples have beendescribed, such as liquid-liquid extraction and soxhlet extraction. The samplepretreatment methods are time-consuming and organic solvent wasting. Magneticsolid phase micro-extraction （MSPME） has been developed as a fast, simple,effective and versatile extraction method, and has been applied to the extraction ofthe analytes in many fields. Single drop micro-extraction （SDME） is widely used inthe extraction of volatile components or semi-volatile components. It is one of thenewly developed sample pretreatment procedure and has received great attention due to its characteristics of low organic solvent consupmtion and easily operation. In thisthesis, we established a series of novel analytical methods based on MSPME andSDME, and investigated their application in the treatment of environmental andmedicinal samples.1. The new C18-functionalized ultrafine magnetic silica nanoparticles （C18-UMSNPs） were successfully synthesized by chemical coprecipitation, silanization andalkylation method and applied for extraction of sudan dyes in water samples basedon the magnetic solid phase micro-extraction （MSPME）. The extraction andconcentration were carried out in one step by blending C18-UMS NPs and watersamples. The sudan dyes adsorbed C18-UMS NPs were isolated from the matrixeasily with an external magnetic field. After desorption the quantitation of sudandyes was done by ultra fast liquid chromatography （UFLC）. The effects ofexperimental parameters, including the amount of the nanoparticles, extraction time,pH value, desorption solvent, volume of desorption solvent and desorption time wereinvestigated. The limits of detection for sudan I, II, III and IV were0.07,0.07,0.12and0.12ng mL-1, respectively. Recoveries obtained by analyzing the six spikedwater samples were between68.37%and103.49%. A high enrichment factor can beobtained. Magnetic separation in the method shortened analysis times. C18-UMS NPsshowed great analytical potential in the separation, purification and concentration ofanalytes in large volumes of real water samples.2. A novel method using C18-functional ultrafine magnetic silica nanoparticles（C18-UMS NPs） as adsorbents was developed for rapid extraction and enrichment ofaromatic amines from urine.50mg of C18-UMS NPs was added into the urinesample at pH9, and then the mixture was stirred for20min. After magneticseparation, the C18-UMS NPs adsorbing aromatic amines were placed in3mL ofacetonitrile and the mixture was stirred for1min. After desorption with acetonitrile,the aromatic amines were determined by ultra fast liquid chromatography. Tovalidate the feasibility of the method, five real urine samples were analyzed. Theconcentration of1-aminonaphthalene in one sample is12.8ng mL-1. The limits ofdetection for1-aminonaphthalene,4-aminobiphenyl,4,4’-diaminodiphenylmethane and4-aminophenylthioether were1.3,0.9,1.1and1.1ng mL-1, respectively.Recoveries obtained by analyzing the five spiked urine samples were between70.7%and99.2%.The results showed that the present method was simple, highly efficientand rapid for the extraction and enrichment of aromatic amines from urine.3. Liquid-solid extraction coupled with magnetic solid-phase extraction wassuccessfully developed for the extraction of pyrethroid residues in vegetable samples.The pyrethroids were extracted by liquid-solid extraction and then adsorbed ontomagnetic adsorbent. After desorption the quantitation of pyrethroids was done byUFLC. The effects of the experimental parameters were investigated and optimizedparameters are as follows: liquid-solid extraction solvent, acetone; liquid-solidextraction time,4min; the amount of NaCl,1.0g; the amount of magnetic adsorbent,30mg; magnetic solid-phase extraction time,10min; magnetic solid-phaseextraction desorption solvent, acetone and desorption time,45s. The present methodwas applied to the determination of pyrethroid residues in Chinese cabbage andcelery. Permethrin is detectable in one sample and the concentration of thepyrethroid is19.5ng g-1. The limits of detection for pyrethroids were between0.6and1.2ng g-1. Recoveries obtained by analyzing the four spiked vegetable sampleswere between76.0%and99.5%. The results showed that the present method was asimple, accurate, inexpensive and high efficient approach for the extraction anddetermination of pyrethroids in the vegetable samples.4. Solvent-free microwave extraction coupled with headspace single-dropmicroextraction was developed for extracting the essential oils from Eugeniacaryophyllata Thunb.. Carbonyl iron powders were mixed with the sample to extractessential oils from the dried plant materials and single-drop solvent was used tosimultaneously extract essential oils from the headspace. After the extraction wasfinished, the single-drop was injected into gas chromatographic system and analyzedby GC-MS. The effects of the experimental parameters were investigated andoptimized parameters are as follows: microwave power,350W; microwaveirradiation time,12min; the ratio of carbonyl iron powder to sample,2:1; extractionsolvent, decane; single-drop volume,2μL and HS-SDME time,7min. Sixteen compounds in the essential oils of E. caryophyllata T. were obtained and identified.The constituents of essential oils obtained by hydro-distillation and solvent-freemicrowave extraction headspace single-drop microextraction were not obviouslydifferent. Compared with hydro-distillation, the present method required shorterextraction time and less amounts of the sample and organic solvent. |
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