| In this thesis, the improvement and application of microwave-assisted extraction (MAE) used in extracting chemical constituents from traditional Chinese medicines and spices were studied. A new microwave heating mode was applied in MAE, and the improved solvent-free microwave extraction (ISFME) was developed.By adding microwave absorption solid mediums (MAM) into samples, this proposed method was used to extract essential oils from either dried or fresh samples directly in atmospheric conditions without adding any solvent or water. Three kinds of MAM, such as carbonyl iron powders (CIP), graphite powders (GP) and active carbon powders (ACP), were used and compared with water in microwave absorption capability. The result proved that these MAMs not only had much better microwave absorption capability than water, but also were suitable to be used in ISFME.The essential oils in two kinds of dried traditional Chinese medicine (Pericarpium Citri Reticulatae and Herba menthae), five kinds of dried spice (Pericarpium zanthoxyli, seeds of Cuminum cyminum L., Fructus anisi stellati, Rhizoma zingiberis recens and Fructui Foeniculi) and two kinds of fresh plant sample (orange peel and Bulbus Allii Sativi) were studied by the ISFME, and the extraction products were analysed by GC-MS. The results obtained by the ISFME were then compared with those obtained by conventional solvent-free microwave-assisted extraction (CSFME), microwave-assisted hydrodistillation (MAHD) and conventional hydrodistillation (HD) in the constituents of essential oils, extraction time, electricity consumption and so on. It could be seen from the experimental results that there was no obvious difference in the quality of essential oils obtained by the four kinds of extraction methods, which could suggeset that ISFME was a feasible methods for extracting essential oils from plant samples. The ISFME took only 30min to extract essential oils completely from 100g of dried or fresh plant samples, and the other extraction methods took more time to extract the essential oils completely.The effects of extraction temperature (100℃, 130℃and 150℃) on extraction products and extraction process were discussed. It was found that the extraction time could be shortened at high extraction temperature. However, some thermally unstable compounds may be decomposed at too high temperature. The effects of other experimental conditions (extraction time and the volume of water in extraction system) in four extraction methods on the contents of oxycompounds in essential oils were also discussed.In the study of essential oil of fresh orange peel, the sample was dried in baking oven at 40℃for 24h, and the effect of drying on the components of essential oil was discussed. Through comparing the essential oil in fresh sample with that in dried sample, it was found that drying process could affect the relative contents of some compounds in essential oils.The pressurized microwave-assisted extraction (PMAE) was used for extracting azo dyes from lipsticks. Because lipsticks are some kinds of emplastic which has compact structure and can hardly be neither cleaned up nor extracted easily, a new method for treating with this kind of sample was presented. The lipsticks were coated on glass slide, and then the glass was put into the extraction vessel for extraction. Compared with the conventional treatment of lipsticks, when the proposed method was applied, higher extraction yield of azo dyes was obtained. The extraction conditions, such as extraction solvent, extraction pressure and extraction time, were investigated. Compared with both ultrasonic extraction and thin-layer chromatographic extraction, PMAE takes shorter extraction time and extraction yields of azo dyes obtained by using PMAE are higher.
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