Trace determination of organophosphorus pesticides in environmental samples by temperature-controlled ionic liquid dispersive liquid-phase microextraction

This paper described a new approach for the determination of organophosphorus pesticides by temperature-controlled ionic liquid dispersive liquid-phase microextraction prior to high-performance liquid chromatography with ultraviolet detection. Methylparathion and phoxim, two of the typical organophosphorus pesticides, were used as the model analytes for the investigation of the development and application of the new microextraction method. 1-Hexyl-3-methylimidazolium hexafluorophosphate [C6MIM][PF6] was used as the extraction solvent and the factors affecting the extraction efficiency such as the volume of [C6MIM][PF6], pH of working solutions, extraction time, centrifuging time, dissoluble temperature and salt effect were optimized. Under the optimal extraction conditions, methylparathion and phoxim exhibited good linear relationship in the concentration range of 1-100 ng mL(-1). The detection limits were 0.17 ng mL(-1) and 0.29 ng mL(-1), respectively. Precisions of proposed method (RSDs, n=6) were 2.5% and 2.7%, respectively. This proposed method was successfully applied in the analysis of four real environmental water samples and good spiked recoveries over the range of 88.2-103.6% were obtained. These results indicated that temperature-controlled ionic liquid dispersive liquid-phase microextraction had excellent application prospect in environmental field.     

Ionic liquid sensitized fluorescence determination of four isoquinoline alkaloids

The fluorescence spectra of berberine, palmatine, jatrorrhizine, and coptisine in ionic liquids were studied and found to increase significantly in ionic liquids, with [C(8)MIM][PF(6)] having the greatest increase. Further studies showed that these drugs could be extracted from an aqueous solution by [C(8)MIM][PF(6)] using the temperature-assisted ionic liquid dispersive liquid phase microextraction method. The enrichment factors were 81.8-82.3, and the extraction recovery was 98.5%, 98.1%, 98.3%, and 98.8% for berberine, palmatine, jatrorrhizine, and coptisine, respectively. Based on the [C(8)MIM][PF(6)] preconcentration, separation, and sensitized fluorescence for these drugs, a new selective and sensitive method for the determination of concentration of these four drugs in aqueous samples was presented. At optimum conditions, the linear relationship was obtained in the ranges of 0.8-130 ng mL(-1), 0.9-160 ng mL(-1), 0.7-140 ng mL(-1), and 0.6-110 ng mL(-1), respectively. The proposed method was successfully applied for the determination of the drugs in pharmaceutical preparations, urine, and plasma samples.     

Use of a novel medium, the ionic liquid 1-butyl-3-trimethylsilylimidazolium hexafluorophosphate, for liquid-liquid extraction of lead in water and its determination by graphite furnace atomic absorption spectrometry

The ionic liquid 1-butyl-3-trimethylsilylimidazolium hexafluorophosphate, abbreviated as [C4tmsim][PF6], was developed as a novel medium for liquid-liquid extraction of lead(II) in water, in which dithizone was used as a metal chelator to form a neutral lead-dithizone complex. Under optimal conditions, the complex was extracted into the [C4tmsim][PF6] phase from aqueous solution and back-extracted with nitric acid solution into the aqueous phase that was used directly for the subsequent determination of Pb. The system using the ionic liquid demonstrated good extraction performance; the extraction and back-extraction efficiencies were 99.8 and 99.7%, respectively, for Pb(II) at 20 microg/L. The above procedure, including the extraction and back-extraction, was used to enrich trace levels of Pb(ll) in a relatively large volume of water samples (1000 mL water), and an enrichment factor of 400 was obtained. The enrichment coupled with graphite furnace atomic absorption spectrometry was successfully applied to the determination of Pb in water. The calibration graph was linear at levels near the detection limits up to > or = 100 ng/L Pb(II). The limits of quantitation and detection for lead in real water samples were 2.5 and 1.0 ng/L, respectively. Lead recoveries of 96.2-103.8% from spiked samples demonstrate the accuracy of the proposed method.     

Ionic liquid-based liquid-phase microextraction, a new sample enrichment procedure for liquid chromatography

Room temperature ionic liquids (RTILs) were used as extraction solvent in liquid-phase microextraction (LPME) coupled with liquid chromatography. Using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) as extraction solvent, some parameters related to LPME of 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP) were optimized. Although [C6MIM][PF6] can suspend a much larger volume of drop on the needle of the microsyringe than the conventional solvents such as 1-octanol and carbon tetrachloride, the method sensitivity was analyte dependent because of the different partition coefficients and the relatively large viscosity of [C6MIM][PF6]. The proposed procedure has a detection limit and enrichment factor of 0.3 microg l(-1) and 163 for 4-NP, and 0.7 microg l(-1) and 130 for 4-t-OP, respectively. Aqueous samples including tap water, river water, and effluent from sewage treatment plant were analyzed by the proposed method and the recoveries at 10 microg l(-1) spiked level were in the range of 90-113%.     

Determination of triclosan and triclocarban in environmental water samples with ionic liquid/ionic liquid dispersive liquid-liquid microextraction prior to HPLC-ESI-MS/MS

A hydrophobic ionic liquid was finely dispersed in aqueous solution along with a hydrophilic ionic liquid. Following centrifugation, the two phases aggregate to form relatively large droplets. Based on this phenomenon, a method termed ionic liquid/ionic liquid dispersive liquid-liquid microextraction was developed. It was applied to the enrichment of triclosan (TCS) and triclocarban (TCC) from water samples prior to HPLC with electrospray tandem MS detection. The type and volume of the hydrophobic ionic liquid (the extraction solvent) and the hydrophilic ionic liquid (the disperser solvent), salt content, and extraction time were optimized. Under optimum conditions, the method gives a linear response in the concentration ranges from 0.5 to 100???g L^?1 for TCC and from 2.5 to 500???g L^?1 for TCS, respectively. The limits of detection are 0.23 and 0.35???g L^?1, and the repeatability is 5.4 and 6.4% for TCC and TCS, respectively. The method was validated with four environmental water samples, and average recoveries of spiked samples were in the range from 88% to 111%. The results indicate that the method is a promising new approach for the rapid enrichment and determination of organic pollutants.

黄连黄柏提取液中3种生物碱的原位生成离子液体微萃取及HPLC测定

通过加入水溶性离子液体[C6MIM][Br]和离子对试剂NaPF6在黄连和黄柏的提取液中,原位生成非水溶性离子液体[C6MIM][PF6]萃取其生物碱,离心分相后,用HPLC测离子液体相中的生物碱小檗碱、巴马汀和黄连碱,其线性相关系数分别为0.9998、0.9996和0.9997,线性范围为1~2000 μg/L,检出限皆为0.5 μg/L,加标回收率96.52%~104.34%。 这种方法可用于黄连和黄柏中的小檗碱、巴马汀和黄连碱的检测。     

Combination of ultrasound-assisted ionic liquid dispersive liquid-phase microextraction and high performance liquid chromatography for the sensitive determination of benzoylureas pesticides in environmental water samples

This paper describes a new method for rapid and sensitive determination of diflubenzuron, flufenoxuron, triflumuron and chlorfluazuron in water samples by ultrasound-assisted ionic liquid dispersive liquid-phase microextraction in combination with HPLC. Ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) was used as the extraction solvent for the enrichment of four benzoylurea (BU) pesticides. Factors such as volume of [C(6)MIM][PF(6)], sonication time, sample pH, extraction time, centrifuging time and salting-out effect were systematically investigated. Under the optimum conditions, an excellent linear relationship was achieved in the range of 1.0-100?μg/L. The detection limits varied from 0.21 to 0.45?μg/L and the precision of the method was below 6.9% (RSD, n=6). The proposed method was successfully applied for the determination of these BU pesticides in water samples and excellent spiked recoveries were achieved. All these results demonstrated that this procedure provided a new simple, rapid, easy to operate, efficient and sensitive method for the analysis of BU pesticides in aqueous samples.     

水样中氟罗沙星和磺胺喹噁啉的离子液体均匀提取

提出一种新的离子液体均匀提取方法,即向水样中加入可溶于水的离子液体1-己基-3-甲基咪唑四氟硼酸盐([C6MimBF4]),再加入过量六氟磷酸铵(NH4PF6),形成不溶于水的离子液体1-己基-3-甲基咪唑六氟磷酸盐([C6MimPF6]),水样中的氟罗沙星和磺胺喹噁啉被提取到[C6MimPF6]相,离心分离后,离子液体可直接用于HPLC分析.本法测得的氟罗沙星和磺胺喹噁啉的检出限分别为1.8和1.1μg/L.     

Ionic liquid for high temperature headspace liquid-phase microextraction of chlorinated anilines in environmental water samples

Based on the non-volatility of room temperature ionic liquids (IL), 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]) IL was employed as an advantageous extraction solvent for high temperature headspace liquid-phase microextraction (LPME) of chloroanilines in environmental water samples. At high temperature of 90 degrees C, 4-chloroaniline, 2-chloroaniline, 3,4-dichloroaniline, and 2,4-dichloroaniline were extracted into a 10 microl drop of [C4MIM][PF6] suspended on the needle of a high-performance liquid chromatography (HPLC) microsyringe held at the headspace of the samples. Then, the IL was injected directly into the HPLC system for determination. Parameters related to LPME were optimized, and high selectivity and low detection limits of the four chlorinated anilines were obtained because the extraction was performed at high temperature in headspace mode and the very high affinity between IL and chlorinated anilines. The proposed procedure was applied for the analysis of the real samples including tap water, river water and wastewater samples from a petrochemical plant and a printworks, and only 3,4-dichloroaniline was detected in the printworks wastewater at 88.2 microg l(-1) level. The recoveries for the four chlorinated anilines in the four samples were all in the range of 81.9-99.6% at 25 microg l(-1) spiked level.     

Extraction and Determination of Two Antidepressant Drugs in Human Plasma by Dispersive Liquid–Liquid Microextraction‒HPLC

In this study, an effective method of ultrasound-assisted ionic liquid based dispersive liquid–liquid microextraction (UA?IL?DLLME) coupled with HPLC was applied for extraction and determination of two antidepressant drugs: venlafaxine hydrochloride and amitriptyline hydrochloride from human plasma samples. Three ionic liquids were studied: 1-butyl-3-methyl imidazolium hexafluorophosphate, 1-hexyl-3- methyl imidazolium hexa-fluoro-phosphate, and 1-octyl-3-methyl imidazolium hexafluorophosphate [C8MIM][PF6]. Various factors affect the stages and efficiency of extraction, some of which are pH of sample solution, type and volume of ionic liquid, the time of ultrasonication, centrifuging time and rate, and the ionic strength of solution. In this research, optimum conditions were obtained as 55 μL of [C8MIM][PF6] selected as ionic liquid, pH 11, 2% NaCl, 4 min ultrasonication and 5 min centrifuging at 3500 rpm. Under the optimized conditions, the linearity was obtained in the range of 0.2 to 250 μg/L. The limits of detection were 0.5 μg/L for venlafaxine and 0.8 μg/L for amitriptyline. Pre-concentration factors were 1.3 × 10³ for venlafaxine and 1.2 × 10³ for amitriptyline. The UA?IL?DLLME method coupled with HPLC was successfully used for the determination of venlafaxine and amitriptyline spiked into the real samples of human plasma.     

Determination of sudan dyes in red wine and fruit juice using ionic liquid-based liquid-liquid microextraction and high-performance liquid chromatography

The liquid-liquid microextraction (LLME) was developed for extracting sudan dyes from red wine and fruit juice. Room temperature ionic liquid was used as the extraction solvent. The target analytes were determined by high-performance liquid chromatography. The extraction parameters were optimized. The optimal conditions are as follows: volume of [C(6)MIM][PF(6)] 50 μL; the extraction time 10 min; pH value of the sample solution 7.0; NaCl concentration in sample solution 5%. The extraction recoveries for the analytes in red wine and fruit samples are 86.79-108.28 and 68.54-85.66%, whereas RSDs are 1.42-5.12 and 1.43-6.19%, respectively. The limits of detection and quantification were 0.428 and 1.426 ng/mL for sudan I, 0.938 and 3.127 ng/mL for sudan II, 1.334 and 4.445 ng/mL for sudan III, 1.454 and 4.846 ng/mL for sudan IV, respectively. Compared with conventional liquid-liquid extraction (CLLE) and ultrasonic extraction (UE), when LLME was applied, the sample amount was less (LLME: 4 mL; CLLE: 10 mL; UE: 10 mL), the extraction time was shorter (LLME: 15 min; CLLE: 110 min; UE: 50 min) and the extraction solvent amount was less (LLME: 0.05 mL IL; CLLE: 15 mL hexane; UE: 20 mL hexane). The proposed method offers a simple, rapid and efficient sample preparation for determining sudan dyes in red wine and fruit juice samples.     

Aqueous interfaces with hydrophobic room-temperature ionic liquids: a molecular dynamics study

We report a molecular dynamics study of the interface between water and (macroscopically) water-immiscible room-temperature ionic liquids "ILs", composed of PF6(-) anions and butyl- versus octyl-substituted methylimidazolium+ cations (noted BMI+ and OMI+). Because the parameters used to simulate the pure ILs were found to exaggerate the water/IL mixing, they have been modified by scaling down the atomic charges, leading to better agreement with the experiment. The comparison of [OMI][PF6] versus [BMI][PF6] ILs demonstrates the importance of the N-alkyl substituent on the extent of solvent mixing and on the nature of the interface. With the most hydrophobic [OMI][PF6] liquid, the "bulk" IL phase is dryer than with the [BMI][PF6] liquid. At the interface, the OMI+ cations retain direct contacts with the bulk IL, whereas the more hydrophilic PF6(-) anions gradually dilute in the local water micro-environment and are thus isolated from the "bulk" IL. The interfacial OMI+ cations are ordered with their imidazolium moiety pointing toward the aqueous side and their octyl chains toward the IL side of the interface. With the [BMI][PF6] liquid, the system gradually evolves from an IL-rich to a water-rich medium, leading to an ill-defined interfacial domain with high intersolvent mixing. As a result, the BMI+ cations are isotropically oriented "at the interface". Because the imidazolium cations are more hydrophobic than the PF6(-) anions, the charge distribution at the interface is heterogeneous, leading to a positive electrostatic potential at the interface with the two studied ILs. Mixing-demixing simulations on [BMI][PF6]/water mixtures are also reported, comparing Ewald versus reaction field treatments of electrostatics. Phase separation is very slow (at least 30 ns), in marked contrast with mixtures involving classical organic liquids, which separate in less than 0.5 ns at the microscopic level. The results allow us to better understand the specificity of the aqueous interfaces with hydrophobic ionic liquids, compared with classical organic solvents, which has important implications as far as the mechanism of liquid-liquid ion extraction is concerned.     

超声辅助离子液体液相微萃取-高效液相色谱法分析水样中加替沙星或氟罗沙星

建立了一种采用离子液体1-己基-3-甲基咪唑六氟磷酸([C6mim][PF6])为萃取剂,超声辅助离子液体液相微萃取-高效液相色谱法分析水样中加替沙星和氟罗沙星的方法。 实验考察了溶液酸度、离子液体用量等因素对萃取的影响。在pH值分别为3.3、2.1的加替沙星和氟罗沙星水样中,加入0.4 mL [C6mim][PF6],超声,离心,离子液体相直接用于HPLC进行分析。 该方法的线性范围为0.5~50 mg/L,测定加替沙星和氟罗沙星的相对标准偏差(n=5)为2.80%和5.93%,二者的检出限分别为0.46、0.97 μg/L,该方法萃取水样中加替沙星的加标回收率为80.5%~89.5%,氟罗沙星的加标回收率可达93.3%~99.0%。     

Dispersive liquid-liquid microextraction of pesticides and metabolites from soils using 1,3-dipentylimidazolium hexafluorophosphate ionic liquid as an alternative extraction solvent

In this work, the use of the ionic liquid (IL) 1,3-dipentylimidazolium hexafluorophosphate ([PPIm][PF?]) as an alternative extractant for IL dispersive liquid-liquid microextraction (IL-DLLME) of a group of pesticides and metabolites (2-aminobenzimidazole, carbendazim/benomyl, thiabendazole, fuberidazole, carbaryl, 1-naphthol, and triazophos) from soils is described. After performing an initial ultrasound-assisted extraction (USE), the IL-DLLME procedure was applied for the extraction of these organic analytes from soil extracts. Separation and quantification was achieved by high-performance liquid chromatography (HPLC) with fluorescence detection (FD). Calibration, precision, and accuracy of the described USE-IL-DLLME-HPLC-FD method using [PPIm][PF?] as an alternative extractant was evaluated with two soils of different physicochemical properties. Accuracy percentages were in the range 93-118% with RSD values below 20%. A comparison of the performance of [PPIm][PF?] versus that of the so-common 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIm][PF?]) was accomplished. Results indicate a comparable extraction efficiency with both ILs, being slightly higher with [HMIm][PF?] for the metabolite 2-aminobenzimidazole, and slightly higher with [PPIm][PF?] for triazophos. In all cases, LODs were in the low ng/g range (0.02-14.2 ng/g for [HMIm][PF?] and 0.02-60.5 ng/g for [PPIm][PF?]). As a result, the current work constitutes a starting point for the use of the IL [PPIm][PF?] for further analytical approaches.     

Determination of triazines in honey by dispersive liquid–liquid microextraction high-performance liquid chromatography

Dispersive liquid–liquid microextraction (DLLME) high-performance liquid chromatography (HPLC) was developed for extraction and determination of triazines from honey. A room temperature ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate [C₆MIM][PF_6.], was used as extraction solvent and Triton X 114 was used as dispersant. A mixture of 175 μL [C₆MIM][PF₆] and 50 μL 10% Triton X 114 was rapidly injected into the 20 mL honey sample by syringe. After extraction, phase separation was performed by centrifugation and the sedimented phase was analyzed by HPLC. Some experimental parameters, such as type and volume of extraction solvent, concentration of dispersant, pH value of sample solution, salt concentration and extraction time were investigated and optimized. The detection limits for chlortoluron, prometon, propazine, linuron and prebane are 6.92, 5.84, 8.55, 8.59 and 5.31 μg kg⁻¹, respectively. The main advantages of the proposed method are simplicity of operation, low cost, high enrichment factor and extraction solvent volume at microliter level. Honey samples were analyzed by the proposed method and obtained results indicated that the proposed method provides acceptable recoveries and precisions.     

Temperature‐controlled ionic liquid dispersive liquid‐phase microextraction combined with HPLC with ultraviolet detector for the determination of fungicides

Present study described a simple, environmental benign, easy to operate, and determination method for fungicides including thiram, metalaxyl, diethofencarb, myclobutanil, and tebuconazole. The method is based on temperature‐controlled ionic liquid dispersive liquid phase microextraction coupled to HPLC with ultraviolet detector. In the enrichment procedure, ionic liquid 1‐octyl‐3‐methylimidazolium hexafluorophosphate [C₈MIM][PF₆] was used as the extraction solvent. Variable affecting parameters such as the volume of [C₈MIM][PF₆], temperature, extraction time, centrifuging time, and salting‐out effect have been optimized in detail. Under the optimal conditions, this method has been found to have good linear relationship in the concentration range of 1.0–100 μg/L and excellent detection sensitivity with LODs (S/N = 3) in the range of 0.32–0.79 μg/L. Precisions of proposed method were in the range of 3.7–5.9% for intraday and 7.8–11.0% for interday (RSDs, n = 6). The proposed method was used for the analysis of real water samples and good spiked recoveries at two different spiked levels were achieved in the range of 84.6–102%.     

Efficient Extractive Desulfurization of Fuel Oils Using N‐Pyrrolidone/Alkylphosphate‐Based Ionic Liquids

Four BrØsted acid ionic liquids (ILS) [MMP][DMP], [MEP][DEP], [HMP][DMP] and [HEP][DEP] were synthesized and used as extractants for desulfurization of aromatic sulfur compounds in model oil. The mutual solubility of four ILs were investigated. The extraction equilibrium of four ILs could be reached in as soon as 5 min and the extraction capability followed the order [MMP][DMP]>[MEP][DEP]>[HEP][DEP]>[HMP][DMP]. The S extraction showed the highest efficiency under the conditions of 30°C, 30 min and 1:1 (V/V) IL:oil. Under the optimal condition, 70.9% of thiophene (TS), 76.9% of benzothiophene (BT) and 87.5% of dibenzothiophene (DBT) in n‐octane could be efficiently removed by [MMP][DMP]. The multiple extraction and regeneration performance of [MMP][DMP] for TS was also investigated and the results were satisfying. These results suggest that [MMP][DMP] has the best extraction capability and can serve as a promising solvent for extractive desulfurization of fuel oils.     

Surface characterization of functionalized imidazolium-based ionic liquids

The surface composition of oligo(ethylene glycol) ether functionalized bis(trifluoromethylsulfonyl)imide ionic liquids has been studied by means of X-ray photoelectron spectroscopy (XPS). For [Me(EG)MIM][Tf 2N], [Et(EG) 2MIM][Tf 2N], and [Me(EG) 3MIM][Tf 2N], which vary by the number of ethylene glycol (EG) units (from 1 to 3), we have shown that the stoichiometry of the surface near region is in excellent agreement with the bulk stoichiometry, which confirms the high purity of the ionic liquid samples investigated and rules out pronounced surface orientation effects. This has been deduced from the experimental observation that the angle-resolved XP spectra of all elements present in the IL anions and cations (C, N, O, F, S) show identical signals in the bulk and surfaces sensitive geometry, i.e., at 0 degrees and 70 degrees emission angle, respectively. The relative intensity ratios of all elements were found to be in nearly perfect agreement with the nominal values for the individual ILs. In contrast to these findings, we identified surface-active impurities in [Me(EG)MIM]I, which is the starting material for the final anion exchange step to synthesize [Me(EG)MIM][Tf 2N]. Sputtering of the surface led to a depletion of this layer, which however recovered with time. The buildup of this contamination is attributed to a surface enrichment of a minor bulk contamination that shows surface activity in the iodide melt.     

Nanoscale organization of ionic liquids and their interaction with peptides probed by C NMR spectroscopy

An NMR study of 10 l-alanine- and l-valine-containing peptides was carried out in the native [C₂MIM][Cl], [C₄MIM][Cl], [C₆MIM][Cl], [C₄MIM][BF₄], [C₄MIM][PF₆], and [C₄Py][BF₄] ionic liquid media. A unique high sensitivity of the ionic liquid system to the nature of peptide and ability to tune solvent–solute interactions were observed in contrast to regular organic solvents. The l-valine peptides can be selectively dissolved in [C₄MIM][Cl] and [C₆MIM][Cl], whereas their solubility in [C₂MIM][Cl] and other ionic liquids was dramatically lower. In spite of structural similarity between the amino acids, a distinct behavior was observed for the l-alanine peptides. Solvent–solute interactions with an ionic liquid impose significant changes, and NMR spectroscopy is a useful probe for the molecular-level and nanoscale organization of the studied systems. An even/odd effect of the number of amino acids in the peptide on molecular interactions in ionic liquids was observed. Enhancement of chemical properties of peptides in ionic liquids and application of ionic liquids in the separation of peptides are the areas of practical interest in the studied systems.     

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。