Study On Ionic Liquid-based Liquid Phase Microextraction Of Active Constituents From Chinese Herbs

The research on active constituents of Chinese herbs is of the vital practicalsignificance for realizing the normalization, standardization and modernization ofChinese herbs and advancing Chinese herbs to the world. The reliable extractionmethods, which are the foundation of Chinese herbs analysis, have therefore becomean important part of Chinese herbs research. The extraction of active constituentsfrom Chinese herbs was conventionally performed by solvent extraction,sublimation, pressing and distillation. Unfortunately, these methods are usually timeconsuming, laborious, and a large amount of hazardous and volatile organic solventsare required, although the methods are often effective. In recent years, thedevelopment of some new extraction methods, such as ultrasound-associatedextraction and microwave-assisted extraction, greatly promote the development ofChinese herbs analysis. These new extraction methods have obvious advantages inefficiency, energy conservation and environmental protection. Ionic liquids recentlyemerge as possible “green” solvents which have many unique properties, and haveattracted increasing interest in many field. In this thesis, based on the extration yieldsof active constituents, ionic liquids were used to pretreat Chinese herbs, by some newmethods.1. Ultrasonic-assisted ionic liquid liquid phase microextraction （UAILLPME）was developed and coupled with HPLC for simultaneous determination of shikoninand β,β’-dimethylacrylshikonin in Arnebia euchroma （Royle） Johnst. The driedsample powder was mixed with IL to form a suspension, and then the ultrasonicextraction was performed. Endly, the filtered extract was analyzed by HPLC. Severalparameters of UAILLPME were optimized and three samples obtained from differentcultivated areas were analyzed. The results indicate that the contents of shikonin andβ,β’-dimethylacrylshikonin are in the range of0.20-0.35μg/mg and1.63-2.53μg/mg, respectively. The RSDs were lower than5%. The calibration curves showed good linear relationship （r>0.9998） in the concentration range of1.75–140.00μg/mLfor shikonin and2.15–1360.00μg/mL for β,β’-dimethylacrylshikonin. Spikedsamples were analyzed, and the recoveries were in the range of69.79%to82.35%.Compared with UAE and SE, the present method consumes less sample, time andsolvent, and there is no significant difference in the obtained extraction yields.2. Microwave-assisted homogeneous ionic liquid microextraction （MAHILME）has been developed and coupled with HPLC for simultaneous determination ofschizandrin, schisantherin A and deoxyschizandrin in Schisandra chinensis （Turcz.）Baill.（S. chinensis） and Schisandra sphenanthera Rehd. et Wils.（S. sphenanthera）.ILs can efficiently absorb microwave energy.[C₄MIM][BF₄] was used as extractionsolvent, and [NH₄][PF₆] was used as ion-pairing agent.[C₄MIM][PF₆], which isbarely soluble in water, was formed in situ, and the analytes were extracted into thephase. After centrifuging, the IL phase was separated and used as sample solution.Three samples of S. chinensis and two samples of S. sphenanthera were analyzed. Theresults indicated that the contents of schizandrin, schisantherin A anddeoxyschizandrin in S. chinensis were in the range of5.45-6.47μg/mg,1.08-2.17μg/mg and1.01-2.16μg/mg, and those in S. sphenanthera were in the range of0.12-0.14μg/mg,1.63-3.62μg/mg and2.30-4.28μg/mg, respectively. The recoverieswere between69.71%and88.33%with RSDs lower than4.68%. Compared with UEand SE, there is no significant difference in the obtained extraction yields, while thepresent method consumes less sample, time and solvent.