| Ultrasonic nebulization extraction (UNE) is a new method for the preparation ofsamples, which is based on ultrasound assisted extraction (UAE). Compared with UAE,UNE was performed at higher frequency (about1.7MHz). During the UNE, samplewas stretched, torn, and sprayed and both the “ultrasonic fountain” and aerosol canform at the same time. The process for the sample preparation was called UNE byusing the special acoustic properties, i.e., ultrasonic fountain and aerosol. UNE, whichis based on cavitation effect, mechanical effect, thermal effect and fountain effect, wasquick, efficient and solvent saving. In this thesis, the UNE coupled with solid phaseextraction (SPE) was established and applied for sample preparation in the analysis oftraditional Chinese medicine.In this thesis, the UNE coupled with SPE was used to extract non-volatile activeand harmful constituents in traditional Chinese medicines. The conditions of theexperiments were optimized and the experimental results were compared withconventional extraction methods. The research was divided into four parts, and theresearch contents and results were described as follows:The UNE coupled with SPE was applied to the extraction of euphol and tirucallolin the root of Euphorbia pekinensis Rupr. Several parameters of UNE, including typeof extraction solvent, sample amount, type and amount of SPE, SPE time and volumeof the elution solvent were examined. The optimized parameters were also selected.Under the selected conditions, the extraction yields of euphol and tirucallol weredetermined. The recoveries of the analytes were in the range of89.1%to102.0%. Thelimits of detection were12.0mg/g for tirucallol and10.0mg/g for euphol. Theextraction yields obtained by the present method are higher than those obtained by theconventional extraction methods. Compared with the traditional methods, when thepresent method was applied, the consumption of the solvent was reduced, the samplepreparation time was shortened and the extraction efficiency increased.The UNE was developed and applied to the extraction of eight kinds of ginsenosides in the leaves of American ginseng (Panax quinquefolium L.). The0.30gof sample powders and15.00mL of water were mixed in extraction vessel. The totalextraction time was40min. Once the extraction was performed for20min, the SPEbegan and was completed for20min. The analytes were determined by HPLC after theSPE column was eluted by methanol. The yields of eight kinds of ginsenosides were3.2-5.4mg/g for Rg1,15.0-30.2mg/g for Re,1.3-3.4mg/g for Rb1,0.2-1.5mg/g for Rg2,3.0-6.6mg/g for Rc,4.6-10.1mg/g for Rb2,14.1-22.6mg/g for Rb3,6.3-10.3mg/g forRd. The recoveries of the Rg1, Re, Rb1, Rg2, Rc, Rb2, Rb3and Rd were in the range of92.0-100.5,95.0-102.3,85.3-98.0,80.0-102.0,93.1-103.4,97.4-101.3,98.3-100.1and96.1-101.4%, respectively. Compared with ultrasound assisted extraction (UAE) andreflux extraction (RE), when the present method was applied, the extraction yieldswere higher, the operation was easier, and the consumption of organic solvent andenergy was lower.The UNE was also applied to the extraction of six metabolites of ginsenosides inplasma. In this experiment, the plasma was held in silica gel. After removal of thesmall polar components by cyclohexane, the metabolites were quickly eluted by theaerosol of methanol. The eluate was collected and concentrated to200μl, and theanalytes were determined by HPLC. The recoveries of the metabolites were in therange of80.5-102.3%. Relative standard deviation (RSD) was used to represent theprecision. The weekly RSDs were in the range of2.3-4.5%, and monthly RSDs were inthe range of3.4-7.5%. Compared with traditional methods, the recoveries were similar,but the sample storage time was longer.The UNE was applied to the extraction of five kinds of the triazine herbicides in theroot of Panax ginseng C. A. Mey. In this method, the sample powders were mixed withsilica gel, on which the ionic liquid (IL) has been adsorbed. After matrix solid phasedispession extraction was finished for5min in the agate mortar, the mixture was addedinto extraction vessel containing20mL of water. During the solid phase extraction, theanalytes were extracted in the presence of ultrasonic wave and transferred to theadsorbents by the ultrasonic fountain at the same time. In the absence of the carrier gas,both the processes of extraction and enrichment were completed at the same time.Under the selected optimum parameters, recoveries of the five kinds of the triazineherbicides were in the range of73.1%to95.6%. Limits of detection of the five kindsof triazines were in the range of2.0to3.5ng/g. The intra-day and inter-day RSDswere in the range of3.8%to6.5%. Compared with other methods, when the present method was applied, the extraction efficiency was higher, the operation was easier,extraction time was shorter, and energy consumption was lower.In this thesis, the appliciation of UNE in the extraction of traditional Chinesemedicine was studied. It was proved that UNE is an effective method to extract thenon-volatile components. When the present method was coupled with other methods,the extraction and enrichment could be finished at the same time. When the UNE wasapplied, the sample preparation time was shortened, the extraction efficiency wasimproved and the enrichment factor increased. The results obtained by presentmethods will help greatly to extend the application of UNE. |
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