Sequential dispersive liquid–liquid microextraction for the determination of aryloxyphenoxy‐propionate herbicides in water

A novel dispersive liquid–liquid microextraction (DLLME) method followed by HPLC analysis, termed sequential DLLME, was developed for the preconcentration and determination of aryloxyphenoxy‐propionate herbicides (i.e. haloxyfop‐R‐methyl, cyhalofop‐butyl, fenoxaprop‐P‐ethyl, and fluazifop‐P‐butyl) in aqueous samples. The method is based on the combination of ultrasound‐assisted DLLME with in situ ionic liquid (IL) DLLME into one extraction procedure and achieved better performance than widely used DLLME procedures. Chlorobenzene was used as the extraction solvent during the first extraction. Hydrophilic IL 1‐octyl‐3‐methylimidazolium chloride was used as a dispersive solvent during the first extraction and as an extraction solvent during the second extraction after an in situ chloride exchange by bis[(trifluoromethane)sulfonyl]imide. Several experimental parameters affecting the extraction efficiency were studied and optimized with the design of experiments using MINITAB® 16 software. Under the optimized conditions, the extractions resulted in analyte recoveries of 78–91%. The correlation coefficients of the calibration curves ranged from 0.9994 to 0.9997 at concentrations of 10–300, 15–300, and 20–300 μg L^?1. The relative SDs (n = 5) ranged from 2.9 to 5.4%. The LODs for the four herbicides were between 1.50 and 6.12 μg L^?1.     

Ionic‐liquid‐based,manual‐shaking‐ and ultrasound‐assisted,surfactant‐enhanced emulsification microextraction for the determination of three fungicide residues in juice samples

A novel manual‐shaking‐ and ultrasound‐assisted surfactant‐enhanced emulsification microextraction method was developed for the determination of three fungicides in juice samples. In this method, the ionic liquid, 1‐ethyl‐3‐methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, instead of a volatile organic solvent was used as the extraction solvent. The surfactant, NP‐10, was used as an emulsifier to enhance the dispersion of the water‐immiscible ionic liquid into an aqueous phase, which accelerated the mass transfer of the analytes. Organic dispersive solvent typically required in common dispersive liquid–liquid microextraction methods was not necessary. In addition, manual shaking for 15 s before ultrasound to preliminarily mix the extraction solvent and the aqueous sample could greatly shorten the time for dispersing the ionic liquid into aqueous solution by ultrasound irradiation. Several experimental parameters affecting the extraction efficiency, including type and volume of extraction solvent, type and concentration of surfactant, extraction time, and pH, were optimized. Under the optimized conditions, good linearity with the correlation coefficients (γ) higher than 0.9986 and high sensitivity with the limit of detection ranging from 0.4 to 1.6 μg/L were obtained. The average recoveries ranged from 61.4 to 86.0% for spiked juice, with relative standard deviations from 1.8 to 9.7%. The proposed method was demonstrated to be a simple, fast, and efficient method for the analysis of the target fungicides in juice samples.     

Ultrasound‐assisted,hybrid ionic liquid,dispersive liquid–liquid microextraction for the determination of insecticides in fruit juices based on partition coefficients

An ultrasound‐assisted, hybrid ionic liquid, dispersive liquid–liquid microextraction method coupled to high‐performance liquid chromatography with a variable‐wavelength detector was developed to detect ten insecticides, including diflubenzuron, triflumuron, hexaflumuron, flufenoxuron, lufenuron, diafenthiuron, transfluthrin, fenpropathrin, γ‐cyhalothrin and deltamethrin, in fruit juices. In this method, an appropriate extraction solvent was chosen based on the partition coefficient of the target compounds. A mixture of 1‐octyl‐2,3‐dimethylimidazolium bis(trifluoromethylsulfonyl)imide and 1‐hexyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide was used as the extractant. The extraction efficiency was screened using Plackett–Burman design and optimized using central composite design. Under the optimal conditions, good linearity was obtained for all the analytes in the pure water model and the fruit juice samples. In pure water, the recoveries of the ten insecticides ranged from 85.7 to 108.9%, with relative standard deviations for one day ranging from 1.24 to 2.64%. The limits of detection were in the range of 0.19–0.69 μg/L, and the enrichment factors were in the range of 123–160. The logarithm of the n‐octanol/water partition coefficient in this experiment is a useful reference to select a suitable extraction solvent, and the proposed technique was applied for the analysis of ten insecticides in fruit juice with satisfactory results.     

Determination of diflubenzuron and chlorbenzuron in fruits by combining acetonitrile‐based extraction with dispersive liquid–liquid microextraction followed by high‐performance liquid chromatography

In this study, a simple and low‐organic‐solvent‐consuming method combining an acetonitrile‐partitioning extraction procedure followed by “quick, easy, cheap, effective, rugged and safe” cleanup with ionic‐liquid‐based dispersive liquid–liquid microextraction and high‐performance liquid chromatography with diode array detection was developed for the determination of diflubenzuron and chlorbenzuron in grapes and pears. Ionic‐liquid‐based dispersive liquid–liquid microextraction was performed using the ionic liquid 1‐hexyl‐3‐methylimidazolium hexafluorophosphate as the extractive solvent and acetonitrile extract as the dispersive solvent. The main factors influencing the efficiency of the dispersive liquid–liquid microextraction were evaluated, including the extractive solvent type and volume and the dispersive solvent volume. The validation parameters indicated the suitability of the method for routine analyses of benzoylurea insecticides in a large number of samples. The relative recoveries at three spiked levels ranged between 98.6 and 109.3% with relative standard deviations of less than 5.2%. The limit of detection was 0.005 mg/kg for the two insecticides. The proposed method was successfully used for the rapid determination of diflubenzuron and chlorbenzuron residues in real fruit samples.     

Determination of three estrogens and bisphenol A by functional ionic liquid dispersive liquid‐phase microextraction coupled with ultra‐high performance liquid chromatography and ultraviolet detection

A hydroxyl‐functionalized ionic liquid, 1‐hydroxyethyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide, was employed in an improved dispersive liquid‐phase microextraction method coupled with ultra high performance liquid chromatography for the enrichment and determination of three estrogens and bisphenol A in environmental water samples. The introduced hydroxyl group acted as the H‐bond acceptor that dispersed the ionic liquid effectively in the aqueous phase without dispersive solvent or external force. Fourier transform infrared spectroscopy indicated that the hydroxyl group of the cation of the ionic liquid enhanced the combination of extractant and analytes through the formation of hydrogen bonds. The improvement of the extraction efficiency compared with that with the use of alkyl ionic liquid was proved by a comparison study. The main parameters including volume of extractant, temperature, pH, and extraction time were investigated. The calibration curves were linear in the range of 5.0–1000 μg/L for estrone, estradiol, and bisphenol A, and 10.0–1000 μg/L for estriol. The detection limits were in the range of 1.7–3.4 μg/L. The extraction efficiency was evaluated by enrichment factor that were between 85 and 129. The proposed method was proved to be simple, low cost, and environmentally friendly for the determination of the four endocrine disruptors in environmental water samples.     

Determination of triazine herbicides in juice samples by microwave‐assisted ionic liquid/ionic liquid dispersive liquid–liquid microextraction coupled with high‐performance liquid chromatography

A novel microextraction method, termed microwave‐assisted ionic liquid/ionic liquid dispersive liquid–liquid microextraction, has been developed for the rapid enrichment and analysis of triazine herbicides in fruit juice samples by high‐performance liquid chromatography. Instead of using hazardous organic solvents, two kinds of ionic liquids, a hydrophobic ionic liquid (1‐hexyl‐3‐methylimidazolium hexafluorophosphate) and a hydrophilic ionic liquid (1‐butyl‐3‐methylimidazolium tetrafluoroborate), were used as the extraction solvent and dispersion agent, respectively, in this method. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of 1‐hexyl‐3‐methylimidazolium hexafluorophosphate dispersed entirely into sample solution with the help of 1‐butyl‐3‐methylimidazolium tetrafluoroborate. In addition, an ion‐pairing agent (NH₄PF₆) was introduced to improve recoveries of the ionic liquid phase. Several experimental parameters that might affect the extraction efficiency were investigated. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 5.00–250.00 μg/L, with the correlation coefficients of 0.9982–0.9997. The practical application of this effective and green method is demonstrated by the successful analysis of triazine herbicides in four juice samples, with satisfactory recoveries (76.7–105.7%) and relative standard deviations (lower than 6.6%). In general, this method is fast, effective, and robust to determine triazine herbicides in juice samples.     

In situ ionic‐liquid‐dispersive liquid–liquid microextraction of Sudan dyes from liquid samples

In situ ionic‐liquid‐dispersive liquid–liquid microextraction was introduced for extracting Sudan dyes from different liquid samples followed by detection using ultrafast liquid chromatography. The extraction and metathesis reaction can be performed simultaneously, the extraction time was shortened notably and higher enrichment factors can be obtained compared with traditional dispersive liquid–liquid microextraction. When the extraction was coupled with ultrafast liquid chromatography, a green, convenient, cheap, and efficient method for the determination of Sudan dyes was developed. The effects of various experimental factors, including type of extraction solvent, amount of 1‐hexyl‐3‐methylimidazolium chloride, ratio of ammonium hexafluorophosphate to 1‐hexyl‐3‐methylimidazolium chloride, pH value, salt concentration in sample solution, extraction time and centrifugation time were investigated and optimized for the extraction of four kinds of Sudan dyes. The limits of detection for Sudan I, II, III, and IV were 0.324, 0.299, 0.390, and 0.655 ng/mL, respectively. Recoveries obtained by analyzing the seven spiked samples were between 65.95 and 112.82%. The consumption of organic solvent (120 μL acetonitrile per sample) was very low, so it could be considered as a green analytical method.     

Macrocyclic polyamine‐functionalized silica as a solid‐phase extraction material coupled with ionic liquid dispersive liquid–liquid extraction for the enrichment of polycyclic aromatic hydrocarbons

In this study, silica modified with a 30‐membered macrocyclic polyamine was synthesized and first used as an adsorbent material in SPE. The SPE was further combined with ionic liquid (IL) dispersive liquid–liquid microextraction (DLLME). Five polycyclic aromatic hydrocarbons were employed as model analytes to evaluate the extraction procedure and were determined by HPLC combined with UV/Vis detection. Acetone was used as the elution solvent in SPE as well as the dispersive solvent in DLLME. The enrichment of analytes was achieved using the 1,3‐dibutylimidazolium bis[(trifluoromethyl)sulfonyl]imide IL/acetone/water system. Experimental conditions for the overall macrocycle‐SPE–IL‐DLLME method, such as the amount of adsorbent, sample solution volume, sample solution pH, type of elution solvent as well as addition of salt, were studied and optimized. The developed method could be successfully applied to the analysis of four real water samples. The macrocyclic polyamine offered higher extraction efficiency for analytes compared with commercially available C₁₈ cartridge, and the developed method provided higher enrichment factors (2768–5409) for model analytes compared with the single DLLME. Good linearity with the correlation coefficients ranging from 0.9983 to 0.9999 and LODs as low as 0.002 μg/L were obtained in the proposed method.     

Extensible automated dispersive liquid–liquid microextraction

In this study, a convenient and extensible automated ionic liquid-based in situ dispersive liquid–liquid microextraction (automated IL-based in situ DLLME) was developed. 1-Octyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide ([C₈MIM]NTf₂) is formed through the reaction between [C₈MIM]Cl and lithium bis[(trifluoromethane)sulfonyl]imide (LiNTf₂) to extract the analytes. Using a fully automatic SPE workstation, special SPE columns packed with nonwoven polypropylene (NWPP) fiber, and a modified operation program, the procedures of the IL-based in situ DLLME, including the collection of a water sample, injection of an ion exchange solvent, phase separation of the emulsified solution, elution of the retained extraction phase, and collection of the eluent into vials, can be performed automatically. The developed approach, coupled with high-performance liquid chromatography–diode array detection (HPLC–DAD), was successfully applied to the detection and concentration determination of benzoylurea (BU) insecticides in water samples. Parameters affecting the extraction performance were investigated and optimized. Under the optimized conditions, the proposed method achieved extraction recoveries of 80% to 89% for water samples. The limits of detection (LODs) of the method were in the range of 0.16–0.45 ng mL⁻¹. The intra-column and inter-column relative standard deviations (RSDs) were <8.6%. Good linearity (r > 0.9986) was obtained over the calibration range from 2 to 500 ng mL⁻¹. The proposed method opens a new avenue for automated DLLME that not only greatly expands the range of viable extractants, especially functional ILs but also enhances its application for various detection methods. Furthermore, multiple samples can be processed simultaneously, which accelerates the sample preparation and allows the examination of a large number of samples.     

Effect of Ionic Liquid Structure on the Electrochemical Response of Dopamine at Room Temperature Ionic Liquid‐modified Carbon Paste Electrodes (IL–CPE)

In this work 12 different ionic liquids (ILs) have been used added as co‐binders in the preparation of modified carbon paste electrodes (IL–CPEs) used for the voltammetric analysis of dopamine in Britton‐Robinson buffer. The ionic liquids studied were selected based on three main criteria: (1) increasing chain length of alkyl substituents (studying 1‐ethylimidazolium and ethyl, propyl, butyl, hexyl and decylmethylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids); (2) nature of the counter ion (dicyanamide, bis(trifluoromethylsulfonyl)imide and hexafluorophosphate) in 1‐butyl‐3‐methylimidazolium ionic liquids; and (3) cation ring structures (1‐butyl‐3‐methylimidazolium, 1‐butyl‐1‐methylpiperidinium, 1‐butyl‐1‐methylpyrrolidinium and 1‐butyl‐3‐methylpyridinium) in bis(trifluoromethylsulfonyl)imide or hexafluorophosphate (1‐butyl‐3‐methylimidazolium or 1‐butyl‐3‐methylpyridinium as cations) ionic liquids. The use of IL as co‐binders in IL–CPE results in a general enhancement of both the sensitivity and the reversibility of dopamine oxidation. In square wave voltammetry experiments, the peak current increased up to a 400 % when 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide was used as co‐binder, as compared to the response found with the unmodified CPE. Experimental data provide evidence that electrostatic and steric effects are the most important ones vis‐à‐vis these electrocatalytic effects on the anodic oxidation of dopamine on IL–CPE. The relative hydrophilicity of dicyanamide anions reduced the electrocatalytic effects of the corresponding ionic liquids, while the use of 1‐ethyl‐3‐methylimidazolium hexafluorophosphate or 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (two relatively small and highly hydrophobic ionic liquids) as co‐binders in IL–CPE resulted in the highest electrocatalytic activity among all of the IL–CPE studied.     

Dispersive micro‐solid‐phase extraction of benzoylurea insecticides in honey samples with a β‐cyclodextrin‐modified attapulgite composite as sorbent

A β‐cyclodextrin‐modified attapulgite composite was prepared and used as a dispersive micro‐solid‐phase extraction sorbent for the determination of benzoylurea insecticides in honey samples. Parameters that may influence the extraction efficiency, such as the type and volume of the eluent, the amount of the sorbent, the extraction time and the ionic strength were investigated and optimized using batch and column procedures. Under optimized conditions, good linearity was obtained for all of the tested compounds, with R² values of at least 0.9834. The limits of detection were determined in the range of 0.2–1.0 μg/L. The recoveries of the four benzoylurea insecticides in vitex honey and acacia honey increased from 15.2 to 81.4% and from 14.2 to 82.0%, respectively. Although the β‐cyclodextrin‐modified attapulgite composite did not show a brilliant adsorption capacity for the selected benzoylurea insecticides, it exhibited a higher adsorption capacity toward relatively hydrophobic compounds, such as chlorfluazuron and hexaflumuron (recoveries in vitex honey samples ranged from 70.0 to 81.4% with a precision of 1.0–3.7%). It seemed that the logP_ow of the benzoylurea insecticides is related to their recoveries. The results confirmed the possibility of using cyclodextrin‐modified palygorskite in the determination of relatively hydrophobic trace pharmaceutical residues.     

Temperature‐controlled ionic liquid‐dispersive liquid‐phase microextraction for preconcentration of chlorotoluron,diethofencarb and chlorbenzuron in water samples

This article describes a new, rapid and sensitive method for the determination of chlorotoluron, diethofencarb and chlorbenzuron from water samples with temperature‐controlled ionic liquid‐dispersive liquid‐phase microextraction. In the preconcentration procedure, ionic liquid 1‐hexyl‐3‐methylimidazolium hexafluorophosphate [C₆MIM] [PF₆] was employed as the extraction solvent. The parameters, such as volume of [C₆MIM] [PF₆], sample pH, extraction time, centrifuging time, temperature and salting‐out effect, were investigated in detail. Under the optimal extraction conditions, it has been found that three analytes had excellent LODs (S/N=3) in the range of 0.04–0.43 μg/L. The RSDs (n=6) were in the range of 1.3–4.7%. The proposed method was evaluated with lake water, tap water and melted snow water samples. The experimental results indicated that the proposed method had excellent prospect and would be widely used in the future.     

Binary–solvent–based ionic–liquid–assisted surfactant‐enhanced emulsification microextraction for the determination of four fungicides in apple juice and apple vinegar

A binary–solvent–based ionic–liquid–assisted surfactant‐enhanced emulsification microextraction method was developed for the separation/preconcentration and determination of four fungicides (pyrimethanil, fludioxonil, cyprodynil, pyraclostrobin) in apple juice and apple vinegar. A nonchlorinated solvent amyl acetate, which has a lower density than water, was used as the extraction solvent, and an ionic liquid 1‐hexyl‐3‐methylimidazolium hexafluorophosphate, which has a high density and low toxicity, was used as a secondary solvent mixed with the extraction solvent. After centrifugation, the binary solvent drop with a relatively high density was deposited on the bottom of the tube. Some parameters influencing the extraction efficiency of analytes such as type of extraction solvent, ratio of ionic liquid, volume of mixed solvent, type and concentration of surfactant, sample pH, NaCl concentration, and vortex time were investigated and optimized. Under the optimized conditions, the proposed method provided a good linearity in the range of 5–200 μg/L. The limits of quantification of the method were in the range of 2–5 μg/L. The relative standard deviations for interday assays were 1.7–11.9%. The method was applied to the determination of pyrimethanil, fludioxonil, cyprodynil, and pyraclostrobin in apple juice and apple vinegar samples, and the accuracy was evaluated through recovery experiments.     

Temperature‐controlled ionic liquid dispersive liquid‐phase microextraction for the sensitive determination of triclosan and triclocarban in environmental water samples prior to HPLC‐ESI‐MS/MS

A novel dispersive liquid‐phase microextraction method without dispersive solvents has been developed for the enrichment and sensitive determination of triclosan and triclocarban in environmental water samples prior to HPLC‐ESI‐MS/MS. This method used only green solvent 1‐hexyl‐3‐methylimidazolium hexafluorophosphate as extraction solvent and overcame the demerits of the use of toxic solvents and the instability of the suspending drop in single drop liquid‐phase microextraction. Important factors that may influence the enrichment efficiencies, such as volume of ionic liquid, pH of solutions, extraction time, centrifuging time and temperature, were systematically investigated and optimized. Under optimum conditions, linearity of the method was observed in the range of 0.1–20 μg/L for triclocarban and 0.5–100 μg/L for triclosan, respectively, with adequate correlation coefficients (R>0.9990). The proposed method has been found to have excellent detection sensitivity with LODs of 0.04 and 0.3 μg/L, and precisions of 4.7 and 6.0% (RSDs, n=5) for triclocarban and triclosan, respectively. This method has been successfully applied to analyze real water samples and satisfactory results were achieved.     

Preparation and properties of ionic‐liquid‐containing poly(ethylene glycol)‐based networked polymer films having lithium salt structures

Ionic‐liquid‐containing polymer films were prepared by swelling poly(ethylene glycol)‐based networked polymers having lithium salt structures with an ionic liquid, 1‐ethyl‐3‐methylimidazolium bis(fluorosulfonyl)imide (EMImFSI), or with an EMImFSI solution of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI). Their fundamental physical properties were investigated. The networked polymer films having lithium salt structures were prepared by curing a mixture of poly(ethylene glycol) diglycidyl ether and lithium 3‐glycidyloxypropanesulfonate or lithium 3‐(glycidyloxypropanesulfonyl)(trifluoromethanesulfonyl)imide with poly(ethylene glycol) bis(3‐aminopropyl) terminated. The obtained ionic‐liquid‐containing films were flexible and self‐standing. They showed high ionic conductivity at room temperature, 1.16–2.09 S/m for samples without LiTFSI and 0.29–0.43 S/m for those with 10 wt % LiTFSI. Their thermal decomposition temperature was above 220 °C, and melting temperature of the ionic liquid incorporated in the film was around ?16 °C. They exhibited high safety due to good nonflammability of the ionic liquid. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Correlation between the fluorescent response of microfluidity probes and the water content and viscosity of ionic liquid and water mixtures

Accurate data on transport properties such as viscosity are essential in plant and process design involving ionic liquids. In this study, we determined the absolute viscosity of the ionic liquid + water system at water mole fractions from 0 to 0.25 for three 1-alkyl-3-methylimidazolium ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide and 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide. In each case, the excimer to monomer ratio for 1,m-bis(1-pyrenyl)alkanes (m= 3 or 10) was found to increase linearly with the mole fraction of water. Of the probes studied only PRODAN and rhodamine 6G, both of which have the ability to participate in hydrogen bonding, exhibited Perrin hydrodynamic behavior in the lower viscosity bis(trifluoromethane sulfonyl)imides. As a result, these probes allow for the extrapolation of the absolute viscosity of the ionic liquid mixture from the experimental fluorescence steady-state polarization values.     

Extraction of Lithium from Salt Lake Brine with Triisobutyl Phosphate in Ionic Liquid and Kerosene

Three ionic liquids(ILs), namely, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-me- thylimidazolium bis[(trifluoromethyl)sulfonyl]imide and 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sul- fonyl]imide with the triisobutyl phosphate(TIBP) and kerosene system were respectively used to extract lithium ion from salt lake brine with a high concentration ratio of magnesium and lithium experimentally. Results indicate that the highest extraction selectivity for lithium was obtained with IL 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)- sulfonyl]imide. The effects of solution pH and phase ratio R(O/A) on the extractive step and the influence of acid concentration of the stripping solution and R(O/A) on the back extraction step were also investigated systematically. The single-step extraction efficiency of lithium ion was 83.71% under the optimal extraction conditions, and the single-step back extraction efficiency was 85.61% with a 1.0 mol/L HCl in 1.0 mol/L NaCl medium as stripping agent at R(O/A)=2. The liquid-liquid extraction mechanism and the complex of the ligand with lithium were proposed.     

In situ ionic liquid dispersive liquid–liquid microextraction combined with ultra high performance liquid chromatography for determination of neonicotinoid insecticides in honey samples

An efficient in situ ionic liquid dispersive liquid–liquid microextraction followed by ultra‐performance liquid chromatography was developed to determine four neonicotinoid insecticides in wild and commercial honey samples. In this method, a hydrophobic ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate, formed by in situ reaction between potassium hexafluorophosphate and 1‐butyl‐3‐methylimidazolium bromide in sample solution, was used as the extraction solvent. In comparison with the traditional dispersive liquid–liquid microextraction method, the developed method required no dispersive solvent. To achieve high extraction efficiency and enrichment factor, the effects of various experimental parameters were studied in detail. Under the optimized conditions, the limits of detection and quantification were in the ranges of 0.30–0.62 and 1.20–2.50 μg/L, respectively. The method showed high enrichment factors (74–115) with the recoveries between 81.0 and 103.4%. The proposed method was finally applied to different wild and commercial honey samples.     

苄基功能化离子液体对有机磷和苯环化合物的分散液-液微萃取性能研究

以苄基功能化的离子液体1-苄基-3-甲基咪唑双三氟甲烷磺酰亚胺(1-Benzyl-3-methylimidazolium bis [(trifluoromethyl)sulfonyl]imide,[BeMIM][Tf2 N])作为分散液-液微萃取的萃取剂,与高效液相色谱联用,用于环境水样中5种有机磷农药(辛硫磷、杀螟松、毒死蜱、甲拌磷和对硫磷)以及2种苯环化合物(氯化萘和蒽)的萃取与富集。并与其它离子液体([OMIM][Tf2 N])以及普通有机溶剂(CCl4和 C2 Cl4)的萃取效能进行了对比。萃取优化条件为：40μL [BeMIM][Tf2 N]作为萃取剂,1 mL 甲醇作为分散剂,离心时间5 min,样品溶液中不添加盐。在优化的条件下,本方法的线性关系良好(R2=0.9994~0.9998);对10,40和100μg/ L 不同添加浓度重复测定5次的日内和日间 RSD 分别为1.1%~4.3%和0.8%~4.8%,LOD 为0.01~1.0μg/ L (S/ N=3)。将本方法用于3种实际水样中目标分析物的测定,加标回收率和 RSD 分别为82.7%~118.3%和0.7%~5.6%。由于在咪唑环上引入了苄基基团,[BeMIM][Tf2 N]与目标分析物之间除存在疏水作用外,还存在π-π作用,故对目标物的萃取效率明显提高,富集倍数和回收率分别高达339和81.4%。测定了分析物在[BeMIM][Tf2 N]-DLLME 体系中的分配系数,对萃取机制进行初步探讨。     

Ionic‐liquid‐based surfactant‐emulsified microextraction procedure accelerated by ultrasound radiation followed by high‐performance liquid chromatography for the simultaneous determination of antidepressant and antipsychotic drugs

In the present work, an efficient and environmental friendly method of ionic‐liquid‐based emulsified microextraction procedure accelerated by ultrasound radiation has been developed. Subsequently, its performance was compared with dispersive liquid–liquid microextraction and ultrasound‐assisted surfactant‐based emulsification microextraction methods. The optimization of experimental conditions was carried out by combination of central composite design and response surface methodology. The optimum conditions of variables were set as follows: 50 μL of 1‐hexyl‐3‐methylimidazolium hexafluorophosphate (extracting solvent), 10 min ultrasound time, and 10 min vortex time for agitating 6 mL sample solution in pH 3 in the presence of 4 mg sodium dodecyl sulfate without addition of salt and 200 μL of methanol as diluent solvent. Under these conditions, the responses are linear for doxepin and perphenazine in the range of 0.3–1000 and 5–1000 μg/L, respectively. The limits of detection were 0.1 μg/L for doxepin and 1 μg/L for perphenazine. Relative standard deviations were lower than 3.5 for the determination of both species. Finally, the method was used for the preconcentration and determination of doxepin and perphenazine in urine sample with relative recoveries in the range of 89–98%.