Temperature-assisted ionic liquid dispersive liquid-liquid microextraction combined with high performance liquid chromatography for the determination of anthraquinones in Radix et Rhizoma Rhei samples

In this article, a novel method termed as temperature-assisted ionic liquid dispersive liquid-liquid microextraction (TA IL-DLLME) combining high performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of anthraquinones in Radix et Rhizoma Rhei samples. The ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate) was used to replace volatile organic solvent as an extraction solvent for the extraction of anthraquinones (aloe-emodin, rhein, emodin, chrysophanol and physcion) from Radix et Rhizoma Rhei. Several important parameters influencing the extraction efficiency of TA IL-DLLME such as the type and volume of extraction solvent and disperser solvent, sample pH, extraction time, extraction temperature, centrifugation time as well as salting-out effects were optimized. Under the optimal conditions, the spiked recovery for each analyte was in the range of 95.2-108.5%. The precisions of the proposed method were varied from 1.1% to 4.4% (RSD). All the analytes exhibited good linearity with correlation coefficients (r²) ranging from 0.9986 to 0.9996. The limits of detection for all target analytes were ranged from 0.50 to 2.02 μg L⁻¹ (S/N = 3). The experimental results indicated that the proposed method was successfully applied to the analysis of anthraquinones in Radix et Rhizoma Rhei.     

Application of dispersive liquid-liquid microextraction and high-performance liquid chromatography for the determination of three phthalate esters in water samples

A novel method, dispersive liquid-liquid microextraction (DLLME) coupled with high-performance liquid chromatography-variable wavelength detector (HPLC-VWD), has been developed for the determination of three phthalate esters (dimethyl phthalate (DMP), diethyl phthalate (DEP), and di-n-butyl phthalate (DnBP)) in water samples. A mixture of extraction solvent (41 μL carbon tetrachloride) and dispersive solvent (0.75 mL acetonitrile) were rapidly injected into 5.0 mL aqueous sample for the formation of cloudy solution, the analytes in the sample were extracted into the fine droplets of CCl₄. After extraction, phase separation was performed by centrifugation and the enriched analytes in the sedimented phase were determined by HPLC-VWD. Some important parameters, such as the kind and volume of extraction solvent and dispersive solvent, extraction time and salt effect were investigated and optimized. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 5 to 5000 ng mL⁻¹ for target analytes. The enrichment factors for DMP, DEP and DnBP were 45, 92 and 196, respectively, and the limits of detection were 1.8, 0.88 and 0.64 ng mL⁻¹, respectively. The relative standard deviations (R.S.D.) for the extraction of 10 ng mL⁻¹ of phthalate esters were in the range of 4.3-5.9% (n = 7). Lake water, tap water and bottled mineral water samples were successfully analyzed using the proposed method.     

分散液-液微萃取-高效液相色谱法测定环境水样中的多环芳烃

建立了简便、快速、有效的分散液-液微萃取-高效液相色谱-荧光检测(DLLME-HPLC-FLD)测定环境水样中15种多环芳烃(PAHs)的方法。重点探讨了萃取剂的种类和用量、分散剂的种类和用量以及萃取时间等对PAHs萃取效率的影响。在优化的条件下,评价了方法的可靠性。15种PAHs在0.01～10 μg/L范围内呈良好的线性关系,相关系数r均不小于0.9913,峰面积的相对标准偏差(RSD)在2.3%～4.7%之间(n=6)。在优化条件下,富集因子和萃取回收率良好,分别为674～1032和67.4%～103.2%,15种PAHs的检出限(S/N=3)在0.0003～0.002 μg/L之间。建立的方法应用于敖江水样中PAHs的检测,平均加标回收率在79.5%～92.3%之间,RSD在4.3%～6.7%范围内(n=5)。该方法适用于环境水样中痕量PAHs的分析。     

Quantitation of antioxidants in water samples using ionic liquid dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection

A simple and efficient method, ionic liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV), has been applied for the extraction and determination of some antioxidants (Irganox 1010, Irganox 1076 and Irgafos 168) in water samples. The microextraction efficiency factors were investigated and optimized: 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)MIM][PF(6)] (0.06 g) as extracting solvent, methanol (0.5 mL) as disperser solvent without salt addition. Under the selected conditions, enrichment factors up to 48-fold, limits of detection (LODs) of 5.0-10.0 ng/mL and dynamic linear ranges of 25-1500 ng/mL were obtained. A reasonable repeatability (RSD≤11.8%, n=5) with satisfactory linearity (r(2)≥0.9954) of the results illustrated a good performance of the presented method. The accuracy of the method was tested by the relative recovery experiments on spiked samples, with results ranging from 85 to 118%. Finally, the method was successfully applied for determination of the analytes in several real water samples.     

Novel method for the determination of five carbamate pesticides in water samples by dispersive liquid-liquid microextraction combined with high performance liquid chromatography

A novel method for the determination of five carbamate pesticides(metolcarb,carbofuran,carbaryl,isoprocard and diethofencard)in water samples was developed by dispersive liquid-liquid microextraction(DLLME)coupled with high performance liquid chromatography-diode array detector(HPLC-DAD).Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results.Under the optimum conditions for the method,the calibration curve was linear in the c...     

Dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-ultraviolet detection for the determination of three triazole derivatives in environmental water samples

A simple and efficient method known as dispersive liquid-liquid microextraction (DLLME) was demonstrated for the extraction of triadimefon, uniconazole and tebuconazole in real water samples prior to high performance liquid chromatography-ultraviolet detection (HPLC-UV). Several related parameters that could affect the extraction efficiencies were also investigated and optimised. Under the optimum conditions, a linear range was obtained between the peak area and the concentration of the interested analytes over the concentration range of 1.5–100?µg?L^?1 for triadimefon, 2.0–100?µg?L^?1 for uniconazole and tebuconazole, respectively. The limits of detection (LODs) (S/N?=?3) values were in the range of 0.9–1.2?µg?L^?1. The intra-day and inter-day precisions for the analysis ranged from 2.8 to 7.6%. The relative recoveries of the three analytes in tap, well and lake water samples were in the range of 90.6–105.3%. Finally, a comparison of the sensitivity between the proposed DLLME and the improved single-drop microextraction was also evaluated.     

Ionic liquid/ionic liquid dispersive liquid-liquid microextraction

In this article, a novel and simple microextraction method, termed ionic liquid/ionic liquid dispersive liquid–liquid microextraction (IL/IL‐DLLME), has been designed and developed for the rapid enrichment and analysis of environmental pollutants. Instead of using hazardous organic solvents, two kinds of ILs, hydrophobic IL and hydrophilic IL, were used as extraction solvent and disperser solvent in IL/IL‐DLLME step, respectively. Permethrin and biphenthrin, two of the often‐used pyrethroid pesticides, were used as model compounds. Factors that may affect the enrichment efficiencies were investigated and optimized in detail. Under optimum conditions, permethrin and biphenthrin exhibited a wide linear relationship over the range 1–100 μg/L. For permethrin and biphenthrin, the precisions were 4.65–7.78%, and limits of detection were found to be 0.28 and 0.83 μg/L, respectively. Satisfactory results were achieved when the present method was applied to analyze the target compounds in real‐world water samples with spiked recoveries over the range 84.1–113.5%. All these facts indicated that IL/IL‐DLLME is a simple and rapid alternative for the enrichment and analysis of environmental pollutants and will have a wide application perspective in the future.     

Recent trends in replacement of disperser solvent in dispersive liquid-liquid microextraction methods

Since its innovation in 2006, the dispersive liquid-liquid microextraction (DLLME) method has attracted the attention of analytical chemists in the field of sample preparation. This method has been successfully applied to determine trace amounts of pollutants in various matrices, but the restriction in the choice of suitable disperser and extraction solvents, and high disperser solvent consumption leading to decreased partition coefficients of the analytes between aqueous phase and extractant are its problems. To solve these drawbacks and develop environmentally friendly techniques, various alternatives for the conventional DLLME have been presented. The current review will begin with an introduction to the sample preparation, implementation of DLLME, and its advantages. Then, we focus on its drawbacks, which result mainly from the use of disperser solvent. Afterward, some of the most interesting approaches that have been employed and published until now are reviewed. Finally, an outlook on the future of these techniques will be given.     

Ionic liquid based dispersive liquid-liquid microextraction of aromatic amines in water samples

In this work, a new microextraction method termed ionic liquid based dispersive liquid-liquid microextraction （IL-DLLME） was demonstrated for the extraction of 2-methylaniline, 4-chloroaniline, 1-naphthylamine and 4-aminobiphenyl in aqueous matrices. After extraction the ionic liquid （IL） phase was injected directly into the high performance liquid chromatography （HPLC） system for determination. Some parameters that might affect the extraction efficiency were optimized. Under the optimum conditions, good linear relationship, sensitivity and reproducibility were obtained. The limits of detection （LOD, S/N = 3） for the four analytes were in the range of 0.45-2.6 μg L^-1. The relative standard deviations （R.S.D., n = 6） were in the range of 6.2-9.8%. This method was applied for the analysis of the real water samples. The recoveries ranged from 93.4 to 106.4%. The main advantages of the method are high speed, high recovery, good repeatability and volatile organic solvent-free.     

分散液液微萃取技术及其在生物样品分析中的研究进展

分散液液微萃取是一种新型微萃取技术,具有易操作、低成本、耗时短、环境友好、萃取效率高等优点。该文着眼于分散液液微萃取技术中萃取剂的性质及辅助分散方式,综述了常规分散液液微萃取、离子液体分散液液微萃取、超声辅助分散液液微萃取等多种萃取模式,并重点归纳总结了近5年分散液液微萃取技术在生物样品分析领域的应用进展。     

Dispersive liquid-liquid microextraction combined with high performance liquid chromatography-fluorescence detection for the determination of carbendazim and thiabendazole in environmental samples

A rapid and sensitive method for the determination of carbendazim (methyl benzimidazole-2-ylcarbamate, MBC) and thiabendazole (TBZ) in water and soil samples was developed by using dispersive liquid-liquid microextraction (DLLME) coupled with high performance liquid chromatography with fluorescence detection. The water samples were directly used for the DLLME extraction. For soil samples, the target analytes were first extracted by 0.1 mol L⁻¹ HCl. Then, the pH of the extract was adjusted to 7.0 with 2 mol L⁻¹ NaOH before the DLLME extraction. In the DLLME extraction method, chloroform (CHCl₃) was used as extraction solvent and tetrahydrofuran (THF) as dispersive solvent. Under the optimum conditions, the enrichment factors for MBC and TBZ were ranged between 149 and 210, and the extraction recoveries were between 50.8 and 70.9%, respectively. The linearity of the method was obtained in the range of 5-800 ng mL⁻¹ for water sample analysis, and 10-1000 ng g⁻¹ for soil samples, respectively. The correlation coefficients (r) ranged from 0.9987 to 0.9997. The limits of detection were 0.5-1.0 ng mL⁻¹ for water samples, and 1.0-1.6 ng g⁻¹ for soil samples. The relative standard deviations (RSDs) varied from 3.5 to 6.8% (n = 5). The recoveries of the method for MBC and TBZ from water samples at spiking levels of 5 and 20 ng mL⁻¹ were 84.0-94.0% and 86.0-92.5%, respectively. The recoveries for soil samples at spiking levels of 10 and 100 ng g⁻¹ varied between 82.0 and 93.4%.     

Determination of phthalate esters in water samples by ionic liquid cold-induced aggregation dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography

A novel method, termed ionic liquid cold-induced aggregation dispersive liquid–liquid microextraction (IL-CIA-DLLME), combined with high-performance liquid chromatography (HPLC) was developed for the determination of three phthalate esters in water samples. Several important parameters influencing the IL-CIA-DLLME extraction efficiency, such as the type of extraction and disperser solvent, the volume of extraction and disperser solvent, temperature, extraction time and salt effect, were investigated. Under optimal extraction conditions, the enrichment factors and extraction recoveries ranged from 174 to 212 and 69.9 to 84.8%, respectively. Excellent linearity with coefficients of correlation from 0.9968 to 0.9994 was observed in the concentration range of 2–100 ng mL⁻¹. The repeatability of the proposed method expressed as relative standard deviations ranged from 2.2 to 3.7% (n = 5). Limits of detection were between 0.68 and 1.36 ng mL⁻¹. Good relative recoveries for phthalate esters in tap, bottled mineral and river water samples were obtained in the ranges of 91.5–98.1%, 92.4–99.2% and 90.1–96.8%, respectively. Thus, the proposed method has excellent potential for the determination of phthalate esters in the environmental field.     

分散液液微萃取-衍生化高效液相色谱-荧光检测法测定环境水样中4种酚类内分泌干扰物

为实现小体积环境水样中酚类化合物的准确、快速、高灵敏测定,通过分散液液微萃取(DLLME)和荧光衍生化的结合,建立了高效液相色谱-荧光检测(HPLC-FLD)双酚A、壬基酚、辛基酚和对特辛基酚的分析方法。考察并优化了DLLME和衍生化条件,结果表明,最优的DLLME条件为萃取剂氯仿用量70μL,分散剂乙腈用量400μL,漩涡振荡3 min,高速离心2 min。以2-[2-(7 H-二苯并[a,g]咔唑-乙氧基)]-乙基氯甲酸酯(DBCEC-Cl)为柱前衍生试剂,在pH10.5的Na2CO3-NaHCO3缓冲液/乙腈溶液、50℃下衍生反应3 min得到稳定的衍生产物,于10min内实现了4种酚衍生物的分离。方法的检出限为0.9~1.6 ng/L,定量限为3.8~7.1 ng/L,具有良好的线性、精密度和回收率,与以往报道的方法相比具有一定的优势和实用性,可用于造纸厂废水、湖水、生活废水、自来水中4种酚类内分泌干扰物的测定。     

分散液液微萃取-反相液液微萃取-扫集-胶束电动色谱法测定红酒中的3种氯酚类物质

建立了分散液液微萃取（DLLME）-反相液液微萃取（RP-LLME）-扫集-胶束电动色谱富集模型,并用于红酒中五氯酚（PCP）、2,4,6-三氯酚（TCP）和2,4-二氯酚（DCP）3种氯酚的测定。实验考察了两步微萃取的萃取参数对氯酚萃取率的影响和样品分离富集的电泳条件。最佳萃取条件DLLME为：3.5 mL红酒（pH 3.0,120 g/L NaCl）,300 μL正己烷（萃取剂）;RP-LLME为：25 μL 0.16 mol/L NaOH（萃取剂）。最佳电泳条件：25 mmol/L NaH₂PO₄,100 mmol/L十二烷基硫酸钠（SDS）,30%（v/v）乙腈,pH 2.3;分离电压-15 kV;样品基质为80 mmol/L NaH₂PO₄;压力进样20 s×20.67 kPa（3 psi）。PCP和TCP的线性范围为0.5~100 μg/L（r≥0.9910）,DCP的线性范围为1.5~80 μg/L（r=0.9851）。3种分析物的检出限（S/N=3）为0.035~0.114 μg/L,加标回收率为75.2%~104.7%,相对标准偏差≤6.17%。该方法富集倍数高、灵敏度高、重现性好、分析速度快,可为不同样品基质中痕量氯酚污染物及某些弱酸性有机污染物测定提供参考。     

Combination of ionic liquid dispersive liquid-phase microextraction and high performance liquid chromatography for the determination of triazine herbicides in water samples

A temperature-controlled ionic liquid dispersive liquid-phase microextraction in combination with high performance liquid chromatography was developed for the enrichment and determination of triazine herbicides such as cyanazine,simazine,and atrazine in water samples.1-Octyl-3-methylimidazolium hexafluorophosphate([C8MIM][PF6]) was selected as the extraction solvent.Several experimental parameters were optimized.Under the optimal conditions,the linear range for cyanazine was in the concentration range of 0.5–80 mg/L and the linear range for simazine and atrazine was in the range of1.0–100 mg/L.The limit of detection(LOD,S/N = 3) was in the ranges of 0.05–0.06 mg/L,and the intra day and inter day precision(RSDs,n = 6) was in the ranges of 3.2%–6.6% and 4.8%–8.9%,respectively.Four real water samples were analyzed with the developed method,and the experimental results showed that the spiked recoveries were satisfactory.All these exhibited that the developed method was a valuable tool for monitoring such pollutants.     

Ultrasound‐assisted supramolecular‐solvent‐based microextraction combined with high‐performance liquid chromatography for the analysis of chlorophenols in environmental water samples

An efficient, inexpensive and environmentally benign ultrasound‐assisted supramolecular‐solvent‐based microextraction technique combined with high‐performance liquid chromatography was used for the determination of chlorophenols in environmental water samples. Different factors such as amount of decanoic acid, volume of tetrahydrofuran, pH of the sample, ultrasound time and ionic strength were investigated and optimized. The optimized extraction conditions were 60 mg decanoic acid, 1.5 mL tetrahydrofuran, 3 min ultrasound time, without salt addition. Under this condition, the extraction recoveries were 83.0–89.3 with preconcentration factors of 94–102. The calibration curves were linear from 5.0–400.0 ng/mL with square of the correlation coefficient higher than 0.9998 and the limits of detection were between 1.5–2.0 ng/mL. The values of intra‐ and inter‐day relative standard deviations were 3.2–6.0 and 7.3–8.0%, respectively. Analysis of different samples showed that the concentration of 2,5‐dichlorophenol in Babolrood river water was 80.6 ng/mL.     

Determination of phenylurea herbicides in aqueous samples using partitioned dispersive liquid-liquid microextraction

Partitioned dispersive liquid-liquid microextraction (PDLLME), using THF as the dispersive solvent and dichloromethane as the extraction solvent, was utilized to isolate and concentrate phenylurea herbicides (PUHs) from aqueous samples. In PDLLME, a dispersive solvent should be able to partition in the organic extractant droplets to effectively extract the polar organic compounds from aqueous samples. The mixture of the water-immiscible extractant and the partitioned dispersive solvent was obtained by centrifugation, dried under low pressure, reconstituted in methanol-water mixture (1:1), and injected into a HPLC system for the determination of PUHs. The enrichment factors of the PUHs ranged from 68 to 126 under the optimal conditions. The linear range was 0.5-100 ng ml⁻¹ for each analyte, the relative standard deviations of PUHs were in the range of 1.5-5.9% (n = 5), and the detection limits (signal-to-noise ratio of 3) ranged from 0.10 to 0.28 ng ml⁻¹ for the herbicides. The range of intraday precision (n = 5) for PUHs at the levels of 0.5, 5, and 50 ng ml⁻¹ were 3.0-5.9%, 1.8-3.3%, and 2.2-3.6%, respectively. The range of interday precision (n = 5) at 0.5, 5, and 50 ng ml⁻¹ were 0.4-1.8%, 1.2-2.4%, and 0.9-2.3%, respectively. The recoveries of PUHs from three spiked river water samples, at a level of 10 ng ml⁻¹, were 91.2-104.1%. Due to its rapidity, ease of operation, and high recovery, PDLLME can be utilized to isolate and concentrate organic environmental contaminants such as PUHs from aqueous samples.     

基于离子液体的分散液液微萃取-柱前荧光衍生高效液相色谱法测定水样中8种磺胺类药物

建立了一种基于离子液体的分散液液微萃取技术结合柱前荧光衍生高效液相色谱(IL-DLLME-HPLC-FL)对8种磺胺类药物进行检测的方法,并成功应用于实际环境水样的分析。实验考察了萃取参数对磺胺萃取效率的影响及衍生产物的稳定性。最佳实验条件:以40 μL [C₆MIM]PF₆]为萃取剂,0.1 mL丙酮为分散剂,对pH=4且不含NaCl的水溶液进行不超声的分散液液微萃取,并衍生化反应6 h。结果表明:在最佳实验条件下,该法在0.2~10 μg/L和10~500 μg/L两个浓度范围内线性良好,线性相关系数r ≥0.9989;检出限为0.08~0.5 μg/L (S/N=3)。对实验室自来水、湖水、珠江水、池塘水分别加标5、50、200 μg/L的回收率为87.2%~101.4%,相对标准偏差为3.7%~6.2%。该法环保、简便,可用于测定实际水样中磺胺类药物。     

悬浮固化分散液液微萃取-高效液相色谱法测定水体中邻苯二甲酸酯

建立了悬浮固化分散液液微萃取（SFO-DLLME）结合高效液相色谱（HPLC）快速测定水样中6种邻苯二甲酸酯（PAEs）的分析方法。通过对影响萃取效率因素的优化,确定了最佳萃取条件：十二烷醇萃取剂20 μL、萃取温度60℃、离子强度20 g/L、萃取时间1 min。6种PAEs在2~2000 μg/L范围内呈良好的线性关系,相关系数（r）为0.9995~0.9999,检出限（S/N=3）为0.3~0.6 μg/L。对自来水、湖水、江水、污水、海水、市售塑料瓶装纯净水和矿泉水进行测定,能检测到部分PAEs。对加标水样进行回收率试验（10、100和1000 μg/L）,6种PAEs的回收率为84.9%~94.5%,相对标准偏差为4.1%~6.8%（n=5）。该法环保、简单,可用于实际水样中6种PAEs的检测分析。     

Dispersive liquid-liquid microextraction and liquid chromatographic determination of pentachlorophenol in water

A simple and sensitive dispersive liquid-liquid microextraction method for extraction and preconcentration of pentachlorophenol (PCP) in water samples is presented. After adjusting the sample pH to 3, extraction was performed in the presence of 1% W/V sodium chloride by injecting 1 mL acetone as disperser solvent containing 15 μL tetrachloroethylene as extraction solvent. The proposed DLLME method was followed by HPLC-DAD for determination of PCP. It has good linearity (0.994) with wide linear dynamic range (0.1–1000 μg L⁻¹) and low detection limit (0.03 μg L⁻¹), which makes it suitable for determination of PCP in water samples.