Application Of Ionic Liquid Microwave Extraction To Extracting Chemical Constituents From Traditional Chinese Medicines

In this thesis, the Ionic liquid(IL) was used as the microwave absorption medium and applied to the extraction of essential oils from dried traditional Chinese medicines by microwave assisted extraction (MAE). A new microwave heating mode was applied in MAE, and new microwave extraction method was developed.ILs were very suitable for MAE because the ILs can rapidly and effectively absorb the microwave energy. Adding the IL into the extraction system can improve the speed of extraction process. By adding ILs as MAM into samples, the microwave-assisted extraction (ILME) was developed. In another method, ionic liquid and carbonyl iron powder were used as MAMs, the MAM did not mix with the sample and can be reused. Headspace single drop micro-extraction (HS-SDME) coupled with microwave extraction (ME) was developed.The IL was applied to the extraction of essential oils from the dried fruits of the Illicium Verum Hook. f., Cuminum Cyminum L., Cinnamomum cassia Presl and Forsythia suspensa (Thunb.) Vahl by ILME. The proposed method offers a simple, rapid and efficient sample preparation for determination of essential oils in dried plant materials by GC/MS. The extraction time was less than 18 min at the microwave power of 440 W and 1.5mL of ionic liquid was required. Compared with traditional HD, the ILME makes the process more simple and more advantageous in respect of extraction time and sample consumption. Compared with conventional MAE, the green solvent IL was added into the extraction system and little solvent was used in the proposed method. Compared with SFME, the proposed method is simpler and more time-saving because when SFME was applied, for dried materials it was necessary to moisten the sample before extraction. Compared with ISFME, in the ILMAE the IL and sample is an homogenous mixture and the stirring is not required, which makes the extraction system simpler and operation easier.Headspace single drop micro-extraction (HS-SDME) coupled with microwave extraction (ME) and microwave extraction headspace (ME-HS) were developed in order to extract the essential oil from dried Syzygium aromaticum (L.) Merr. Et Perry, Cuminum cyminum L., Cinnamomum cassia Presl and Zingiber Officinale Rosc.. Ionic liquid and carbonyl iron powder were used as microwave absorption medium. The extraction time was less than 7 min at the microwave power of 440 W. 10uL of decane was used as micro-extraction solvent in ME-HS-SDME. The proposed methods were compared with hydrodistillation (HD). There are not obviously different in the constituents of essential oils obtained by the two methods. In the ME-HS-SDME and ME-HS, the best advantage is that MAM can be recycled and are not in contact with the samples.The IL was used as the MAM by adding the sample and ionic liquid-non polar solvent microwave extraction (ILNPSME) was developed. The proposed method was applied to the extraction of the chemical constituents from the root of Panax ginseng C.M.Mey.. The ILNPSME was compared with solid microwave absorption medium-non polar solvent microwave extraction (SMAMNPSME), polar solvent microwave extraction (PSME) and combined solvent microwave extraction (CSME). PSME is suitable to the extraction of polar constituents. The main chemical constituents obtained by SMAMNPSME and ILNPSME are similar, which indicates that the IL can act as an microwave absorption medium and energy translation material.The proposed method has the advantages, such as short extraction time, simple operation and use of green solvent, and is a suitable method to extract the chemical constituents from plant meterials.