Study On Extraction Of Chemical Components From Medicinal Herb And Food Using Hollow Fiber-based Magnetic Bar

In China, traditional Chinese medicine has thousands of years of history. It has asignificant effect for some incurable diseases and little side-effect, and is widely used.The active ingredients in traditional Chinese medicine play a pharmacological role. Soit is very important to study the active ingredients. Traditional extraction methods,such as solvent extraction, maceration extraction, and Soxhlet extraction (SE), havebeen widely applied for extraction of active ingredients. However, these conventionalmethods are usually laborious and time consuming and require a large amount oftoxic and hazardous organic solvents. In recent years, with the development ofeconomic and the improvement of people’s living standards, people are increasinglyconcerned about the safety of the food, especially for the problem of pesticideresidues in food. In order to overcome the problems, in this thesis, a new samplepreparation method hollow fiber magnetic bar liquid phase microextraction(HF-MBLPME) was developed. The present method was successful applied to thestudy of chemical ingredients in traditional Chinese medicine and food.A magnetic bar in HF-MBLPME was used to extract lignans from Wuweizi. Theanalytes were determined by high performance liquid chromatography (HPLC). Astainless-steel wire was inserted into the hollow of the hollow fiber to make themagnetic bar. The bar can be used to stir the extraction system and extract theanalytes, and was isolated from the extraction system by magnetic force. Severalexperimental parameters, including type and volume of extraction solvent, the numberof magnetic bar, extraction temperature and time, stirring speed and NaCl concentration were investigated and optimized. The recoveries were in the range of70.90–106.67%and the RSD were lower than8.84%. The LODs for schisandrin A,schisantherin A, and deoxyschizandrin were0.14,0.06, and0.10μg/mL, respectively.Compared with ultrasound-assisted and Soxhlet extraction, when the present methodwas applied, there is no significant difference in the extraction yields, and theextraction time was shorter, the sample amount was smaller, the consumption oforganic solvent was lower.The HF-MBLPME was applied to the extraction of sulfonylurea herbicides,including nicosulfuron, bensuulfuron-methyl, pyrazosulfuron and chlorimuron-ethyl,in pears. The analytes were determined by HPLC. This present method can makeextraction, separation and pre-enrichment in one step and have the advantages inextraction time and extraction solvent. Several experimental parameters, includingtype of extraction solvent, the number of magnetic bars, extraction temperature andtime, stirring speed, pH and NaCl concentration were investigated and optimized.Under optimal experimental conditions, the calibration curves showed good linearrelationship (r>0.9998). The limits of detection and quantification were in the rangeof7.15-8.26ng/g and24.99-27.52ng/g, respectively. The recoveries were in therange of80.08-105.56%and the relative standard deviations were lower than6.82%.