Studies And Applications On Dispersive Liquid-Liquid Microextraction Applying Low Density Organic Solvent

Dispersive liquid-liquid microextraction(DLLME)is a novel sample pretreatment technique,which incorporates sampling,extraction and enrichment in one step.The advantages of DLLME are rapidity,environmental friendliness,simplicity of operation,low consumption of solvents and time,high enrichment factor and recovery.The purpose of this study was to develop a novel alternative of low-density organic solvent-based dispersive liquid-liquid microextraction coupled with GC-MS to analysis of chemical compounds in aromatic water and essential oil of plants,and polycyclic aromatic hydrocarbons(PAHs)in tap water.A brief description was given as follows:(1)A simply overview about the development process,theoretical basis and factors affecting the extraction efficiency,as well as a detail review of the improvement in dispersive liquid-liquid microextraction,including the type of extraction solvent,the mode of dispersion,the way of demulsification and so on.(2)A novel method of a polyethylene Pasteur pipette-based ultrasound-assisted emulsification microextraction(USAEME)applying low density organic solvent was successfully developed for analysis of chemical constituents in aromatic water from Alpinia katsumadai hayata by gas chromatography-mass spectrpmetry(GC-MS).Factors affecting the extraction process,such as the type and volume of extraction,extraction time were investigated thoroughly and optimized.The optimum extraction conditions:80 ?L of n-hexane,1 mL of aromatic water and 10 min of extraction time,Meanwhile,eucalyptol(28.06%),3-phenyl-2-butanone(22.69%),methyl cinnamate(9.34%),a-terpineol(7.51%),linalool(4.49%),borneol(4.11%),4-terpineol(3.40%),myrtenol(3.77%)were the most abundant volatiles compounds in aromatic water and 52 volatile compounds were identified in this study.The USAEME technique has demonstrated to be simple,efficient,non-expensive and environmentally friendly for the determination of chemical components in aromatic water.(3)1.A novel method of microwave assisted extraction coupled with a polyethylene Pasteur pipette-based dispersive liquid-liquid microextraction applying low density organic solvent(MAE-LDS-DLLME)was successfully developed for the extraction and preconcentration of the essential oil from 3 species of cardamoms(Semen Alpiniae Katsumadai,Fructus Amomi Rotundus and Semen Myristicae).The essential oil was analyzed by gas chromatography-ion trap/mass spectrometry(GC-IT/MS)equipped with a ChromatoProbe direct sample introduction(DSI)device.The effects of various parameters affecting the extraction process,such as the type of extraction solvent and dispersive solvent,ionic strength,microwave power and irradiation time were investigated thoroughly and optimized.The optimal conditions were extraction solvent of toluene,dispersive solvent of methanol,microwave power of 80 W,irradiation time of 4.0 min,plant materials amount of 0.1 g and no addition of salt.By comparison with hydrodistillation,MAE-DLLME-DSI-GC-MS is a simple,rapid,non-expensive,efficient and environmentally friendly method and the essential oil contains higher amounts of oxygenated compounds,which plays an important and valuable role in terms of their contribution to the fragrance of the essential oil.In this paper,we also studied the main components of 3 varieties of cardamoms(Semen Alpiniae Katsumadai,Fructus Amomi Rotundus and Semen Myristicae).The qualitative and quantitative differences in the components of the three essential oils were found be present.This study also provides a new approach for the quality assessment of traditional Chinese medicines.2.A novel method of ultrasonic assisted extraction coupled with a polyethylene Pasteur pipette-based dispersive liquid-liquid microextraction applying low density organic solvent(UAE-LDS-DLLME)was successfully developed for the extraction and preconcentration of the essential oil from fresh flowers of Chimonanthus praecox(L.)Link.The essential oil was analyzed by gas chromatography-ion trap/mass spectrometry(GC-IT/MS)equipped with a ChromatoProbe direct sample introduction(DSI)device.Factors affecting the extraction process,such as the type of extraction solvent and preconcentration solvent were investigated thoroughly and optimized.Methanol was selected as extraction solvent in UAE and disperser solvent in DLLME,and toluene was used as preconcentration solvent in DLLME.The composition of essential oil extracted from fresh flowers of Chimonanthus praecox(L.)Link in different florescence((A)flower buds;(B)at the early stage of flower blooming;(C)during the flower blooming;(D)senescence)were also studied.Under the optimum extraction conditions,the most abundant compounds were elemol,a-guaiene,p-guaiene,(E)-ocimene,caryophyllene,?-cadinene,?-cadinene,?-elemene,?-elemene,a-eudesmol,?-eudesmol and vitamin E.The results demonstrated that UAE-LDS-DLLME coupled with DSI-GC-MS is a simple,rapid,non-expensive and environmentally friendly method and more suitable for semivolatile compounds.(4)A novel method of low density organic solvent-based ultrasound-assisted emulsification microextraction(LDS-U S AEME)coupled with gas chromatography-mass spectrometry was successfully developed for the analysis of 16 polycyclic aromatic hydrocarbons(PAHs)in tap water samples.Factors affecting the extraction process,such as the type and volume of extraction solvent,the time and temperature of ultrasound,ionic strength and extraction mode were investigated thoroughly and optimized.Under the optimized conditions,the method provided a good linearity of calibration curve with the correlation coefficients more than 0.99,RSD values and the limits of detection(S/N=3)varied from 2.2%to 12.6%and from 2.7 to 578.3 ng/L,respectively.The obtainted results showed that LDS-USAEME is a simple,rapid,sensitive and environmentally friendly method for the analysis of PAHs in tap water samples.