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.

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 concentration range from 5 to 1000 ng mL^-1 for all the five carbamate pesticides, with the correlation coefficients （r^2） varying from 0.9984 to 0.9994. Good enrichment factors were achieved ranging from 80 to 177- fold, depending on the compound. The limits of detection （LODs） （S/N = 3） were ranged from 0.1 to 0.5 ng mL^-1. The method has been successfully applied to the analysis of the pesticide residues in environmental water samples.

Dispersive Liquid-liquid Microextraction Combined with High-performance Liquid Chromatography for the Determination of Clozapine and Chlorpromazine in Urine

A simple method has been proposed for the determination of clozapine （CLZ） and chlorpromazine （CPZ） in human urine by dispersive liquid-liquid microextraction （DLLME） in combination with high-performance liquid chromatography-ultraviolet detector （HPLC-UV）. All important variables influencing the extraction efficiency, such as pH, types of the extraction solvent and the disperser solvent and their volume, ionic strength and centrifugation time were investigated and optimized. Under the optimal conditions, the limit of detection （LODs） and quantification （LOQs） of the method were 13 and 39 ng/mL for CLZ, and 2 and 6 ng/mL for CPZ, respectively. The relative standard deviations （RSDs） of the targets were less than 5.1% （C=0.100 μg/mL, n=9）. Good linear behaviors over the tested concentration ranges were obtained with the values of R20.999 for the targets. The absolute extraction efficiencies of CLZ and CPZ from the spiked blank urine samples were 98.3% and 97.8%, respectively. The applicability of the technique was validated by analyzing urine samples and the mean recoveries for spiked urine samples ranged from 93.3% to 105.0%. The method was successfully applied for the determination of CLZ and CPZ in real human urine.

Determination of Amitraz in the Honey Samples by Dispersive Liquid-Liquid Microextraction Followed by Gas Chromatography—Flame Ionization Detection

Dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography–flame ionization detection (GC-FID), as a simple, rapid and efficient method, was developed for the determination of amitraz in honey samples. This method involves the use of an appropriate mixture of the extraction and disperser solvents for the formation of a cloudy solution in 5.0 mL aqueous sample containing amitraz. After extraction, phase separation was performed by centrifugation and the concentrated amitraz in the sedimented phase was determined by gas chromatography—flame ionization detection (GC-FID). Some important parameters such as the type and volume of extraction and disperser solvents, and the effect of pH and salt on the extraction recovery of amitraz were investigated. Under the optimum conditions (13 μL of carbon tetrachloride as an extraction solvent, 1 mL of acetonitrile as a disperser solvent, no salt addition and pH 6) preconcentration factor and the extraction recovery were 955 and 95.5%, respectively. The linear range was 0.01 - 1.0 mg?kg–1 and the limit of detection was 0.0015 mg?kg–1. The relative standard deviation (RSD, n = 4) for 0.1 mg?kg–1 of amitraz was 3.2%. The recoveries of amitraz from honey samples at the spiking levels of 0.1 mg?kg-1 were 78.8 and 98.2%. The results indicated that DLLME is an efficient technique for the extraction of amitraz in honey samples.

Utilization of Dispersive Liquid-Liquid Microextraction Coupled with HPLC-UV as a Sensitive and Efficient Method for the Extraction and Determination of Oleanolic Acid and Ursolic Acid in Chinese Medicinal Herbs

Isomeric triterpenic acids of oleanolic acid (OA) and ursolic acid (UA) both have very low ultraviolet absorption and always exist in the same plant, so the separation and simultaneous determination of them have been a difficult task. In this study, a sensitive method combining dispersive liquid-liquid microextraction (DLLME) with HPLC-UV was developed for the extraction and determination of OA and UA in traditional Chinese medicinal herbs (CMHs). Variables influencing DLLME such as type and volume of extraction solvent, volume of dispersive solvent, ionic strength, aqueous phase pH, extraction time, centrifugation speed and time, and sample volume were investigated and optimized. Under the optimum conditions, both OA and UA attained favorable extraction efficiencies with enrichment factors 1378 and 933, respectively. The linear dynamic ranges of 0.07 - 30.4 μg?mL–1 for OA and 0.08 - 33.6 μg?mL–1 for UA were obtained with square correlation coefficients of 0.9963. The detection limits of OA and UA were both 0.02 μg?mL–1. The method recoveries ranged between 88.2% - 116.2% for OA and 85.7% - 108.2% for UA with the RSDs (n = 5) lower than 8.6%. The proposed method was successfully applied to concentrate and simultaneously determine these two triterpenic acids in Hedyotis diffusa and Eriobotrya japonica samples.

Ionic Liquid-Based Ultrasound-Assisted Emulsification Microextraction Coupled with HPLC for Simultaneous Determination of Glucocorticoids and Sex Hormones in Cosmetics

An effective and environmentally friendly method based on ionic liquid-based ultrasound-assisted emulsification microextraction(IL-USAEME) and high performance liquid chromatography (HPLC) has been developed for the determination of nine hormones including three glucocorticoids, one androgen and five progestogens in cosmetics. Several factors that affect the extraction efficiency, such as the kinds and volume of ionic liquid, salt concentration, ultrasonic power and time, and centrifugation time were investigated and optimized. Under the optimum extraction condition, the recoveries of analytes ranged from 85.97% to 108.84% except prednisolone (62.30%). The intraday and interday precision was below 2.51% and 3.30%, respectively.

Determination of Cobalt in Food, Environmental and Water Samples with Preconcentration by Dispersive Liquid-Liquid Microextraction

A new method for the determination of cobalt was developed by dispersive liquid-liquid microextraction preconcentra-tion and flame atomic absorption spectrometry. In the proposed approach, 1,5-bis(di-2-pyridyl) methylene thiocarbohydrazide (DPTH) was used as a chelating agent, and chloroform and ethanol were selected as extraction and dispersive solvents. Some factors influencing the extraction efficiency of cobalt and its subsequent determination, including extraction and dispersive solvent type and volume, pH of sample solution, concentration of the chelating agent, and extraction time, were studied and optimized. Under the optimum conditions, a preconcentration factor of 8 was reached. The detection limit for cobalt was 12.4 ng?mL–1, and the relative standard deviation (RSD) was 3.42% (n = 7, c = 100 ng?mL–1). The method was successfully applied to the determination of cobalt in food, environmental and water samples.

Evaluation of Response Surface Methodology in Dispersive Liquid-Liquid Microextraction for Lead Determination Using Ionic Liquids

This paper describes a dispersive liquid–liquid microextraction (DLLME) procedure using room temperature ionic liquids (RTILs) coupled with flame atomic absorption spectrometry detection with microsample intro-duction system capable of quantifying trace amounts of lead. In the proposed approach, ammonium pyr-rolidine dithiocarbamate (APDC) was used as a chelating agent and 1-hexyl-3-methylimmidazolium bis (trifluormethylsulfonyl)imid as an extraction solvent was dissolved in acetone as the disperser solvent. The binary solution was then rapidly injected by a syringe into the water sample containing Pb2+ complex. Some factors influencing the extraction efficiency of Pb2+ and its subsequent determination, including extraction and dispersive solvent type, pH of sample solution, concentration of the chelating agent and salt effect were inspected by a full factorial design to identify important parameters and their interactions. Next, a central composite design was applied to obtain the optimum points of the important parameters. Under the optimum conditions, the limit of detection (LOD) was 0.2 μg/L. The relative standard deviation (R.S.D) was 1.4% for 5 μg/L of Pb2+ (n = 7). The relative recovery of lead in seawater, blood, tomato and black tea samples was measured.

Determination of Vanadyl Porphyrins by Liquid-liquid Microextraction and Nano-baskets of p-tert-Calix[4]arene Bearing Di-[N-(X)sulfonye Carboxamide] and Di-(1-propoxy) in Ortho-cone Conformation

Dispersive liquid-liquid microextraction technique was introducd to remove the centrifuging step and conduct inclusion microextraction of charged porphyrins by nano-baskets. For nano-baskets of p-tert-calix[4]arene bearing di-[N-（X）sulfonyl carboxamide] and di-（1-propoxy） in ortho-cone conformation was synthesized and used. The related parameters including ligand concentration, the volume of water disperser, salt effect, and extraction time were optimized. The linear range, detection limit（S/N=3） and precision（RSD, n=6） were determined to be 0.2―50, 0.07 μg/L and 5.3%, respectively. The results reveal that the new approach is competitive analytical tool and an alternative of the traditional methods in the crude oil and related systems.

分散液液微萃取结合气相色谱-四极杆-飞行时间质谱法测定橄榄油中180种农药残留

建立了分散液液微萃取(DLLME)结合气相色谱-四极杆-飞行时间质谱(GC-QTOF MS)快速测定橄榄油中180种农药残留的分析方法,并考察了乙腈酸化浓度、水相体积、萃取剂种类的影响。通过分散液液微萃取进行样品前处理,经含2%甲酸的乙腈溶液提取后,上清液与萃取剂快速注入水相,取待测物供仪器分析,采用基质标准溶液进行定量。结果表明:87.8%农药的线性范围为0.02~2µg/mL,12.2%农药的线性范围为0.1~2µg/mL,相关系数(r^(2))均大于0.99;所有待测农药的检出限为0.002~0.020 mg/kg,定量下限为0.007~0.067 mg/kg,其中有135种农药的定量下限达0.007 mg/kg,23种农药的定量下限达0.017 mg/kg,占总数量的88%;在0.02、0.1、0.2 mg/kg 3个加标水平下,回收率为70%~120%的农药占全部待测农药的76.3%,相对标准偏差(RSD)小于10%的农药占总数的94.4%以上。应用该方法对10份市售橄榄油样品进行检测,共检出5种农药,检出量为0.0057~0.0427 mg/kg。该方法操作简单、快速,精密度及准确度良好,试剂消耗少且绿色环保,能够满足橄榄油中多种农药残留检测的需求。

分散液液微萃取-高效液相测定食用植物油中对羟基肉桂酸和橙皮素含量

通过分散液液微萃取-高效液相(DLLME-HPLC)建立一种同时测定食用植物油中对羟基肉桂酸和橙皮素的分析方法。以正己烷为分散剂,以含体积分数5%氨水(500μL)和体积分数10%乙腈的水溶液为萃取剂萃取样品,以体积分数0.3%三氟乙酸溶液-乙腈为流动相,在柱温25℃条件下进行梯度洗脱,萃取液放置过夜后再进行测定。结果表明:样品峰面积的相对标准偏差均小于3%,对羟基肉桂酸和橙皮素在各自质量浓度范围内的线性相关系数均大于0.99,检测限分别为8.7、6.2 ng/g,定量限分别为26.1、18.5 ng/g,回收率分别为93.1%~103.7%、100.5%~111.1%。

超声辅助分散液液微萃取-气相色谱-质谱法测定玫瑰花水中10种香气组分的含量

提出了超声辅助分散液液微萃取-气相色谱-质谱法测定玫瑰花水中香气组分芳樟醇、乙酸香茅酯、乙酸香叶酯、香茅醇、橙花醇、香叶醇、苯甲醇、苯乙醇、甲基丁香酚、丁香酚含量的方法。取7.0 mL玫瑰花水样品,加入含400μL乙腈、200μL二氯甲烷的分散微萃取溶液,涡旋1 min,超声3 min,离心3 min,收集全部下层沉淀相,注入气相色谱-质谱仪。以HP-INNOWAX色谱柱为固定相,在程序升温条件下分离10种香气组分,以电子轰击离子源电离,外标法定量。结果显示:10种香气组分的质量浓度均在一定范围内和峰面积呈线性关系,检出限(3S/N)为0.050~0.078 mg·L^(−1)。按照标准加入法进行回收试验,回收率为79.8%~114%,测定值的相对标准偏差(n=6)为2.1%~9.6%。

分散液液微萃取-GC-MS/MS测定纺织废水中痕量4-氨基偶氮苯

建立了分散液液微萃取-气相色谱串联质谱法测定纺织废水中偶氮染料释放的痕量4-氨基偶氮苯的新方法。在碱性条件下,用连二亚硫酸钠还原纺织废水试样中的偶氮染料,再以乙腈为分散剂、三氯甲烷为萃取剂对分解生成的4-氨基偶氮苯进行分散液液微萃取,之后采用气相色谱-串联质谱法测定,内标法定量。方法优化了废水试样制备、还原反应条件、分散液液微萃取影响条件以及色谱和质谱条件等。优化的检测方法呈现良好的线性关系,线性范围为0.1~10.0μg/L;方法检出限为0.03μg/L,定量限为0.1μg/L;加标回收率为88.0%~97.0%。该方法具有操作简便、检出限低的优势,能够满足纺织废水中痕量4-氨基偶氮苯的检测。

磁性分散固相微萃取/UHPLC-Q-Orbitrap HRMS测定运动营养食品中27种氨基酸

基于磁性分散固相微萃取净化,建立了测定运动营养食品中27种氨基酸含量的超高效液相色谱-四极杆-静电场轨道阱高分辨质谱法。通过优化液相色谱条件、质谱条件和样品前处理过程,在20 min内实现了对27种目标物的测定。样品经涡旋振荡,超声提取,磁性氧化石墨烯分散固相微萃取净化,采用Thermo Accucore HILIC色谱柱分离,以0.1%甲酸水溶液(含5.0 mmol/L甲酸铵)和0.1%甲酸乙腈(含5.0 mmol/L甲酸铵)为流动相进行梯度洗脱,静电场轨道阱高分辨质谱检测,外标法定量。结果表明,27种目标化合物在一定质量浓度范围内线性良好,相关系数(r^(2))均大于0.99,方法的定量下限为0.10~0.25 mg/kg,平均回收率为70.0%~93.0%,日内相对标准偏差(RSD,n=6)为1.6%~10%,日间RSD(n=5)为1.4%~5.2%。该方法高效灵敏,准确可靠,适用于运动营养食品中27种氨基酸的测定。

Temperature-controlled ionic liquid dispersive liquid phase microextraction combined with ultra-high-pressure liquid chromatography for the rapid determination of triclosan,triclocarban and methyl-triclosan in aqueous samples

As extraction solvents,ionic liquids have green characteristics.In this study,an environmentally benign analytical method termed temperature-controlled ionic liquid dispersive liquid phase microextraction (TIL-DLME) combined with ultra-highpressure liquid chromatography (UHPLC)-tunable ultraviolet detection (TUV) was developed for the pre-concentration and determination of triclosan (TCS),triclocarban (TCC) and methyl-triclosan (M-TCS) in water samples.Significant parameters that may affect extraction efficiencies were examined and optimized,including the types and amount of ionic liquids,volume of the diluent,heating temperature,cooling time,salt effect and pH value.Under the optimum conditions,linearity of the method was observed in the ranges of 0.0100-100 μgL-1 for TCS and M-TCS,and 0.00500-50.0 μgL-1 for TCC with correlation coefficients (r2) > 0.9903.The limits of detection (LODs) ranged from 1.15 to 5.33 ngL-1.TCS in domestic water and TCC in reclaimed water were detected at the concentrations of 1.01 and 0.126 μgL-1,respectively.The spiked recoveries of the three target compounds in reclaimed water,irrigating water,waste water and domestic water samples were obtained in the ranges of 68.4%-71.9%,61.6%-87.8%,58.9%-74.9% and 64.9%-92.4%,respectively.Compared with the previous dispersive liquid-liquid microextraction method (DLLME) about the determination of TCS,TCC and M-TCS,this method is not only more environmentally friendly but also more sensitive.

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.

A novel method for the determination of trace copper in cereals by dispersive liquid-liquid microextraction based on solidification of floating organic drop coupled with flame atomic absorption spectrometry

A novel,simple,rapid,efficient and environment-friendly method for the determination of trace copper in cereal samples was developed by using dispersive liquid-liquid microextraction based on solidification of floating organic drop（DLLME-SFO） followed by flame atomic absorption spectrometry.In the DLLME-SFO,copper was complexed with 8-hydroxy quinoline and extracted into a small volume of 1-dodecanol,which is of low density,low toxicity and proper melting point near room temperature. The experimental parameters affecting the extraction efficiency were investigated and optimized.Under the optimum conditions, the calibration graph exhibited linearity over the range of 0.5—500 ng/mL with the correlation coefficient（r） of 0.9996.The enrichment factor was 122 and the limit of detection was 0.1 ng/mL.The method was applied to the determination of copper in the complex matrix samples such as rice and millet with the recoveries for the spiked samples at 5.0 and 10.0 u,g/g falling in the range of 92.0-98.0%and the relative standard deviation of 3.9-5.7%.

Orthogonal array optimization of ionic liquid based dispersive liquid-liquid microextraction for toxic anilines in foods

A simple and rapid method of ionic liquid based dispersive liquid-liquid microextraction(DLLME) combining with high performance liquid chromatography(HPLC) was developed for the analysis of four toxic anilines in flour steamed bread and maize steamed bread.Several possible influential factors such as the type of ionic liquid and disperser solvent,extraction time,sample pH,ionic strength and the volume of ionic liquid and disperser solvent were optimized using single factor experiments and orthogonal array design(OAD) with OA 25(5 4) matrix.Analysis of variance(ANOVA) and percent contribution(PC) were used to investigate the significance of the factors of OAD.Sample pH and ionic strength are statistically demonstrated two chief factors.Under the optimum condition,the method exhibits a good linearity(r 2 > 0.99) over the studied range(50-1000 ng g 1) for anilines.The extraction factors and recoveries for the anilines in two kinds of steamed breads ranged between 34.1%-73.3% and 44.3%-95.3%,respectively.The limit of detections(LODs) and limit of quantitations(LOQs) ranged between 10-15 ng g 1 and 30-45 ng g-1.

Dispersive liquid–liquid microextraction of silver nanoparticles in water using ionic liquid1-octyl-3-methylimidazolium hexafluorophosphate

Using the ionic liquid（IL）1-octyl-3-methylimidazolium hexafluorophosphate as the extractant and methanol as the dispersion solvent,a dispersive liquid–liquid microextraction method was developed to extract silver nanoparticles（AgN Ps）from environmental water samples.Parameters that influenced the extraction efficiency such as IL concentration,pH and extraction time were optimized.Under the optimized conditions,the highest extraction efficiency for AgN Ps was above 90% with an enrichment factor of 〉90.The extracted AgN Ps in the IL phase were identified by transmission electron microscopy and ultraviolet–visible spectroscopy,and quantified by inductively coupled plasma mass spectrometry after microwave digestion,with a detection limit of 0.01 μg/L.The spiked recovery of AgN Ps was 84.4% with a relative standard deviation（RSD）of 3.8%（n = 6）at a spiked level of 5 μg/L,and 89.7% with a RSD of 2.2%（n = 6）at a spiked level of 300 μg/L,respectively.Commonly existed environmental ions had a very limited influence on the extraction efficiency.The developed method was successfully applied to the analysis of Ag NPs in river water,lake water,and the influent and effluent of a wastewater treatment plant,with recoveries in the range of 71.0%–90.9% at spiking levels of 0.11–4.7 μg/L.

Optimization and Application of Liquid Chromatography Determination of Dispersive Liquid-liquid Microextraction Purified Astaxanthin in Shrimp Waste

A new molecularly imprinted solid-phase extraction（MISPE） monolithic cartridge was synthesized, and MISPE-DLLME（DLLME=dispersive liquid-liquid microextraction） was developed for purification of astaxanthin in shrimp waste. The eluent（methanol） from MISPE was used as the dispersive solvent in subsequent DLLME for further purifying and enriching the analyte prior to high-performance liquid chromatography（HPLC） analysis. The mobile phase was methanol-acetonitrile-water-dichloromethane（85：5：5：5, volume ratio）, flow rate was 0.7 mL/min and UV wavelength was 476 nm. Under optimal conditions, good linearity was obtained in a range of 0.2--200.0 lug/mL（r2=0.9998） with a limit of detection（LOD） of 0.08 Hg/mL, and the extraction recoveries at three spiked levels ranged from 88.3%--92.5% with a relative standard deviation（RSD） less than 4.3%. Moreover, the mean contents of astaxanthin in the three batches of shrimp waste were 95.9, 85.4 and 77.2 μg/g, respectively. This method combining the advantages of MISPE and DLLME results in high selectivity and low cost, which was applied to determining the astaxanthin level in shrimp waste samples.