Research On The Microwave-assisted Extraction Of Essential Oil In Traditional Chinese Medicine And Analysis For The Change Of Chemical Composition

Applicability of Microwave Assisted Extraction of essential oil has the advantages of quickly and efficiently by using the microwave interior heating characteristics. However, the compounds of essential oil would be change or not because of microwave is an electromagnetic wave, and the researches hasn't make a conclusion. In this thesis the essential oil of Illicium verum Hook. f., Zanthoxylum bungeanum Maxim, Mentha hapiocalyx Briq, Zingiber officinale Roscoe, Argy Wormwood Leaf and Agastache rugosa would be extracted by the Solvent Free Microwave Extraction and Microwave Assisted Hydro-distillation. The extraction mechanism of Solvent Free Microwave Extraction and Microwave Assisted Hydro-distillation were investigated. The effective factors which lead essential oil compounds to change were discussed. The main contents of this thesis include the following parts:Firstly: The interior essential oil of gland cell be distilled with the vapour in the process of Solvent Free Microwave Extraction, while in the process of Microwave Assisted Hydro-distillation, the essential oil be extracted into the water, then disstilled with the vapour. It is easy to extract in the small particle or slice which the vegetable gland had no interior or exterior classifies. And the extraction rate of the two microwave-assisted extraction methods are approximation. For the larger particles size of Zanthoxylum bungeanum Maxim had integrity nterior and exterior gland cells and vegetable shape, extraction of essential oil from the cuticulum firstly then the deep via diffusion. So the extraction rate is distinction of the two microwave-assisted extraction methods.Secondly: GC/MS was used for the determination and quantification of chemical composition in the essential oils, and comparison with Hydro-distillation. The results show that, in the extraction of essential oil from Illicium verum Hook. f., Solvent Free Microwave Extraction and Microwave Assisted Hydro-distillation yields the compounds with lower boiling point and more light molecular weight than Hydro-distillation. In the extraction of essential oil from Zanthoxylum bungeanum Maxim, In the same microwave power level of Solvent Free Microwave Extraction, with the time longer, the contents of Trans-4-Isopropyl-1-methyl-2-cyclohexen-1-ol, Cis-4-Isopropyl-1-methyl-2-cyclohexen-1-ol, Eucalyptol, Trans-p-menth-1-en-3-ol and Cis-p-menth-1-en-3-ol are lower, while the content ofα-Linalool is higher. The researches show that with the long extraction time, Eucalyptol would be change intoα-Linalool by the proton catalyze effective cause earrangement reaction. The essential oil which obtained by Hydro-distillation was heating by microwave and then analysis the oils. According to the results, the content of Eucalyptol was lower, while theα-Linalool was higher than before. It is shows that microwave contribution to the rearrangement reaction.In the extraction of essential oil from Mentha hapiocalyx Briq, Solvent Free Microwave Extraction yields highest Pulegone and Mint furanone, lowest Menthol; opposite with Hydro-distillation; and content of Pulegone and Mint furanone Microwave Assisted Hydro-distillation is between Solvent Free Microwave Extraction and Hydro-distillation. The researches show that in the Solvent Free Microwave Extraction with little water, Pulegone and Mint furanone would be contact with oxygen cause oxidation reaction change into another compounds easily. The essential oil which extracted by Hydro-distillation was heating by microwave and then analysis the oils. From the analysis results, the contents of Menthone, Isomenthone, Menthol were lower, and Pulegone and Mint furanone were higher. Especially, the content of Pulegone near with the one which extracted by Solvent Free Microwave Extraction. That shows microwave also effect the oxidation reaction for Menthol oxidized into Pulegone.In the extraction of essential oil from Zingiber officinale Roscoe, Solvent Free Microwave Extraction yields higherβ-phellandrene. The results show that Solvent Free Microwave Extraction trend to yield higher Hydrocarbon monoterpenes which has moer lipophilicify than the Microwave Extraction and Hydro-distillation.