| In recent years, many new sample pretreatment methods were developed andapplied to the extraction and separation of drugs, organic pollutants and natural activeconstituents from a variety of foods and biological matrices. However, theconcentrations of these compounds in the matrices are very low, which makes thesample pretreatment method become a key step in instrumental analysis. Thetraditional sample pretreatment methods are tedious and time-consuming. Moreover,they often require a large number of samples, adsorbent, organic solvent andappropriate manual processing. These traditional sample pretreatment methods havenot been able to satisfy the requirement of modern traditional Chinese medicineanalysis and food analysis. Therefore, it is necessary to establish simple, fast, efficient,environmentally friendly sample pretreatment methods.Matrix solid-phase dispersion (MSPD), a simple, rapid and efficient method ofsample preparation for complex matrices, has been applied to the pretreatment of solid,semi-solid and highly viscous samples. This method requires no or very small solventand often combines extraction, purification and enrichment into a single step. Inaddition, this method does not need tissue homogenate, ultrasound or microwave,precipitation, centrifugation and sample transfer, also does not need special instrumentand equipment. In this thesis, according to the characteristics of MSPD, some new sample pretreatment methods were established to treat traditional Chinese medicineand food samples.In Introduction, the principle, characteristic and applications of matrix solidphase dispersion and ionic liquid-based liquid phase microextraction were reviewed.In Chapter2, nine nucleosides and nucleobases, including uracil, adenine,thymine, uridine, adenosine, thymidine, cytidine, guanosine, and cordycepin in naturalCordyceps sinensis, cultured Cordyceps mycelia and Cordyceps fruiting bodies, wereextracted by matrix solid-phase dispersion and determined by high-performance liquidchromatography. The experimental conditions for the matrix solid-phase dispersionextraction were optimized. Florisil was used as dispersant,15mL of petroleum etheras washing solvent and20mL of methanol as elution solvent. The ratio of Florisil tosample was selected to be4:1and no additional clean-up sorbent was needed. Thestandard curves had good linear relationships (r>0.9997). The limits of detection andquantification were in the range of12～79ng/mL and41～265ng/mL, respectively.Intra-and inter-day precision were lower than8.3%. The recoveries were between61.5%and93.2%. The present method consumed less sample compared withultrasonic extraction and heating reflux extraction. The extraction yields obtained bythe present method are much higher than those obtained by ultrasonic extraction andcomparable to those obtained by heating reflux extraction.In Chapter3, matrix solid phase dispersion and ultrasound-assisted ionicliquid-based homogeneous liquid-liquid microextraction were developed and appliedto the extraction of four tanshinones, including dihydrotanshinone, tanshinone Ⅰ,cryptotanshinone, and tanshinone Ⅱ A in Salvia miltiorrhiza Bge. root. Highperformance liquid chromatography was applied to the separation and determinationof the analytes. The experimental parameters of MSPD and USA-IL-HLLME,including sample amount, the size of sample particle, type of dispersant, ratio ofsample to dispersant, type and volume of elution solvent, type and amount of clean-up,type and volume of ionic liquid, pH value of extraction medium, extractiontemperature, extraction time, amount of ion-pairing agent and centrifuging time, wereinvestigated and optimized. The standard curves showed good linear relationship (r>0.9997). The limits of detection and quantification were in the range of0.052-0.093and0.17-0.31μg/mL, respectively. The recoveries were between70.45%and94.23% with relative standard deviations lower than5.31%.In Chapter4, the silica-supported ionic liquid (S-SIL) was prepared byimpregnation and used as the dispersion adsorbent of matrix solid phase dispersion(MSPD) for the extraction of eight phenolic acidsand flavonoids, including caffeicacid, ferulic acid, morin, luteolin, quercetin, apigenin, chrysin, andkaempferide in rawpropolis. High performance liquid chromatography was applied to the separation anddetermination of the analytes. The experimental conditions for silica-supported ionicliquid-based matrix solid phase dispersion (S-SIL-based MSPD) were optimized.S-SIL containing10%[C6MIM]Cl was used as dispersant,20mL of n-hexaneas aswashing solvent and15mL of methanol as elution solvent. The ratio of S-SIL tosample was selected to be4:1. The standard curves showed good linear relationship (r>0.9995). The limits of detection andquantification were in the range of5.8–22.2ng/mL and19.2–74.0ng/mL, respectively. The relative standard deviations (RSD) ofintra-day and inter-day determination were lower than8.80%and11.19%,respectively. The recoveries were between65.51%and92.32%with RSD lower than8.95%. Compared with ultrasound-assisted extraction (UAE) and soxhlet extraction,the present method consumed less sample, organic solvent, and extraction time,although the extraction yields obtained by S-SIL-based MSPD were slightly lowerthan those obtained by UAE.In Chapter5, the ionic liquid-based matrix solid-phase dispersion homogeneousliquid–liquid microextraction (IL-based MSPD–HLLME) was developed and appliedto the extraction of four banned dyes, including chrysoidin, safranine O, auramine Oand rhodamine B, in condiment samples. High performance liquid chromatographywas applied to the separation and determination of the analytes. The solid sample wasdirectly treated by MSPD using ionic liquid as dispersant and the eluate obtained inMSPD was treated by HLLME. Some experimental parameters, including type ofdispersant, ratio of sample to dispersant,type and volume of ionic liquid, type andvolume of elution solvent, pH value and ionic strength of the elution solvent, amountof ion-pairing agent (NH4PF6), and extraction time, were investigated and optimized.The working curves showed good linear relationship (r>0.9995). The limits ofdetection for the analytes were between6.7and26.8μg/kg and the limits ofquantification were between15.99and58.48μg/kg. When the present method was applied to the analysis of spiked condiment samples, the recoveries of the analytesranged from90.69to113.52%and relative standard deviations were lower than8.2%.The present method has the advantages of MSPD and HLLME, and could be appliedto the determination of syntheticdyes in condiment samples.In Chapter6, the matrix solid-phase dispersion-homogeneous ionic liquidmicroextraction (MSPD-HILME) high-performance liquid chromatography wasdeveloped and applied to the extraction, separation and determination of sevensulfonamides in the kidney, liver and muscle of pig, bovine and chicken. The solidsample was directly treated by MSPD and the eluate obtained in MSPD was treatedby HILME. The ionic liquid was used as microextraction solvent of HILME, whichmay result in the improvement of recoveries of the target analytes. To avoid usingorganic solvent and reduce environment pollution, aqueous solution was used aselution solvent of MSPD. The experimental parameters of the MSPD-HILME,including type and volume of ionic liquid, type of dispersant, ratio of sample todispersant, pH value of elution solvent, volume of elution solvent, amount of salt ineluate, amount of ion-pairing agent (NH4PF6), and centrifuging time, were evaluated.When the present method was applied to the analysis of animal tissues, the recoveriesof the analytes ranged from85.4to118.0%and relative standard deviations werelower than9.30%. The detection limits for the analytes ranged from4.3to13.4μg/kg. |
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