Development Of Ionic Liquid Dispersive Liquid Phase Micro-extraction

Recently, liquid phase microextraction (LPME) has been a novel and environment-friendly sample pretreatment technology, which combined extraction, clean up and concentration in one procedure, and matched the requirement of modern analytical science and technology. It has been proved to be a environmentally benign sample pretreatment method. Dispersive liquid phase microextraction (DLPME) was introduced in recent years as a new extraction mode of LPME, which had advantages such as rapidity, easy to operate and high sensitivity. However, it usually utilized toxic organic solvents as dispersive solvent and extraction solvent for extraction, and which would put potential threat on the environment and the health of operators. So it is of great importance to look for pollution-free, environment friendly and green solvents to replace traditional organic solvents. Room temperature ionic liquids (RTILs) with high stability, good selective solubility, negligible vapor pressure, excellent miscibility with inorganic and organic compounds have aroused increasing interests for their promising role as alternative solvents in separation and analysis. Based on these facts, a novel sample preconcentration technique"ionic liquid dispersive liquid phase microextraction"was designed and developed, and in which IL was the only used extraction solvent and sonication or temperature was used as the driving force for the extraction and phase separation.A review was firstly presented on the classification, characteristics and applications of ionic liquid in extraction and separation. Further, new methods were developed with aromatic amines, chlorotoluron, diethofencarb, benzoylureas pesticides, phthalates esters and pyrethroid insecticides as model analytes using ultrasound-assisted or temperature-controlled ionic liquid dispersive liquid phase microextraction.Ultrasound-assisted ionic liquid dispersive liquid-phase micro-extraction coupled with HPLC was established for the determination of four aromatic amines such as 2, 4-dichloroaniline, 1-naphthylamine, O-chloroanline and N, N-dimethylaniline, and diflubenzuron, flufenoxuron, triflumuron and chlorfluazuron. Variable affecting such as the volume of ionic liquid, sample pH, extraction time, centrifuging time have been investigated in detail. Under the optimal conditions, the detection limits of 2, 4-dichloroaniline, 1-naphthylamine, 6-chloroanline and N, N-dimethylaniline were in the range of 0.17-0.49μg L^-1, and the relative standard deviations were in the range of 2.0-6.1%. The detection limits of diflubenzuron, flufenoxuron, triflumuron and chlorfluazuron were 0.29μgL^-1, 0.45μgL^-1, 0.21μgL^-1, 0.24μgL^-1 respectively, and the relative standard deviations were 2.2-6.9%. The proposed methods were evaluated with real water samples and satisfactory results were achieved.New enrichment and sensitive determination methods for chlorotoluron, diethofencarb and chlorbenzuron, phthalates esters and pyrethroid insecticides were developed with temperature-controlled ionic liquid dispersive liquid phase microextraction in combination with HPLC-UV. Factors that may influence the extraction efficiency were optimized. Under the optimal conditions, the detection limits of chlorotoluron, diethofencarb and chlorbenzuron were 0.04μgL^-1, 0.36μgL^-1, 0.43μgL^-1, respectively, and the relative standard deviations were in the range of 1.3-4.7% for the three targets. The analysis of real water samples resulted in satisfactory r spike recoveries in the range of 86.3-106.5%. As phthalates esters and pyrethroid insecticides were concerned, the linear ranges, precisions and limits of detection were in the range of 1.0-100μgL^-1, 2.2-5.9% and 0.23 0.47μg L^-1, respectively. The proposed method was validated with real water samples and satisfactory spike recoveries in the range of 85.5-102.5% were achieved.The different alkyl and alkyl length in ionic liquid structure would put impact on the extraction of analytes, and the effect was investigated pyrethroid insecticides as the model pollutants. Imidazolium-ILs were selected as extraction solvents. Several factors such as pH of working solution, extraction time dissolved temperature, centrifugation time and salt-out effect were optimized. The results indicated that the the effect of alkyl and length the alkyl chain was proved and [C8MIM] [PF6] provided the best efficiency for these analytes. The experimental results exhibited that the linear ranges, the precisions and detection limits for the selected pollutants were in the range of 1.0-100μg L^-1, 2.0-3.4%, and 0.34-0.48μg L^-1. Real environmental water samples were used for the validating the developed method and satisfactory results were achieved.