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.

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.

Dispersive liquid-liquid microextraction,an effective tool for the determination of synthetic cannabinoids in oral fluid by liquid chromatography-tandem mass spectrometry

In the present work,dispersive liquid-liquid microextraction(DLLME)was used to extract six synthetic cannabinoids(JWH-018,JWH-019,JWH-073,JWH-200,or WIN 55,225,JWH-250,and AM-694)from oral fluids.A rapid baseline separation of the analytes was achieved on a bidentate octadecyl silica hydride phase(Cogent Bidentate C18;4.6 mm×250 mm,4μm)maintained at 37℃,by eluting in isocratic conditions(water:acetonitrile(25:75,V/V)).Detection was performed using positive electrospray ionization-tandem mass spectrometry.The parameters affecting DLLME(pH and ionic strength of the aqueous phase,type and volume of the extractant and dispersive solvent,vortex and centrifugation time)were optimized for maximizing yields.In particular,using 0.5 mL of oral fluid,acetonitrile(1 mL),was identified as the best option,both as a solvent to precipitate proteins and as a dispersing solvent in the DLLME procedure.To select an extraction solvent,a low transition temperature mixture(LTTM;composed of sesamol and chlorine chloride with a molar ratio of 1:3)and dichloromethane were compared;the latter(100μL)was proved to be a better extractant,with recoveries ranging from 73%to 101%by vortexing for 2 min.The method was validated according to the guidelines of Food and Drug Administration bioanalytical methods:intra-day and inter-day precisions ranged between 4%and 18%depending on the spike level and analyte;limits of detection spanned from 2 to 18 ng/mL;matrixmatched calibration curves were characterized by determination coefficients greater than 0.9914.Finally,the extraction procedure was compared with previous methods and with innovative techniques,presenting superior reliability,rapidity,simplicity,inexpensiveness,and efficiency.

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.

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.

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.

Liquid-liquid Microextraction Based on Solidification of Floating Organic Drops Coupled with Gas Chromatography for Analyzing Trace Benzene, Toluene and Xylene in Water Samples

A new liquid-liquid microextraction method based on the solidification of floating organic drops coupled with gas chromatography was developed for the determination of trace benzene, toluene and xylene（BTX） in water samples. In the microextraction procedure, a microdrop of n-decanol was delivered to the surface of the analytes’ solution, and stirred for a desired time. Following the absolute extraction, the sample vial was cooled in an ice bath for 10 min. The solidified n-decanol was then transferred into a plastic tube and melted naturally; and 1 μL of it was injected into gas chromatography for analysis. Factors relevant to the extraction efficiency were studied and optimized. The optimal experimental conditions were： 15 μL of n-decanol as extractive solvent, 30 mL of solution containing analytes, no salt, the stirring rate 400 r/min, the extraction temperature 30 °C, and the extraction time 30 min. Under those optimized conditions, the detection limit（LOD） of analytes was in a range of 0.05―0.10 ng/mL by the developed method. A good linearity（r0.99） in a calibration range of 0.01―100 μg/mL was obtained. The recoveries of the real samples at different spiked levels of BTX were in the range from 92.2% to 103.4%.

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.

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.

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 OA25（54） 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 （r2 〉 0.99） over the studied range （50-1000 ng g-l） 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 be- tween 10-15 ng g-1 and 30--45 ng g-1.

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.

Trace analysis of off-flavor/odor compounds in water using liquid-liquid microextraction coupled with gas chromatography--positive chemical ionization-tandem mass spectrometry

A rapid, inexpensive and laboratory friendly method was developed for analysis of off-flavor/odor compounds in fresh and salt water using gas chromatography with chemical ionization-tandem mass spectrometry. Off-flavor/odor compounds, included geosmin, 2- methylisobomeol （MIB）, 2-isobutyl-3-methyoxypyrazine （IBMP）, and 2-isopropyl-3-methoxypyrazine （IPMP）. Using this method, a single sample can be extracted within minutes using only 1 mL of organic solvent. The ion transitions for IPMP, IBMP, MIB, and geosmin were 153 〉 121, 167 〉 125, 152 〉 95, and 165 〉 109, respectively. The linearity of this method for analyzing MIB ranged from 4 to 200ng·L^-1, and from 0.8 to 200ng·L^-1 for the other analytes. Method recoveries ranged from 97% to 111% and percent relative standard deviations ranged from 3% to 9%, indicating that the method is accurate, precise, and reliable.

Ionic Liquid-based Microwave-assisted Liquid-liquid Microextraction and High Performance Liquid Chromatography Determination of Sulfonamides from Animal Oils

The authors performed ionic liquid-based microwave-assisted liquid-liquid microextraction（IL-based MALLME） coupled with high performance liquid chromatographic separation for the determination of 6 sulfonamides （SAs） from animal oils. The target analytes were extracted from animal oil samples with sodium hydroxide solution containing 1-butyl-3-methylimidazolium tetrafluoroborateand as the extraction solvent under microwave irradiation. The experimental parameters of the IL-based MALLME, including types of ILs, volume of IL, amount of ion-pairing agent（NHaPF6）, pH value of sample solution, and extraction temperature and time were evaluated. The limits of detection and quantification obtained were in a range of 0.4--0.5μg/kg and a range of 1.2--1.8μg/kg, respectively. The accuracy of the method was evaluated by analyzing five spiked animal oil samples at two fortified levels（5 and 50μg/kg）, and the recoveries of SAs varied from 81.4% to 114.5% with relative standard deviations ranging from 0.8% to 9.0%.

Dispersive Liquid-liquid Microextraction for Simultaneous Determination of Six Parabens in Aqueous Cosmetics

A simple and rapid sample preparation method of dispersive liquid-liquid microextraction（DLLME） was applied in the simultaneous determination of six parabens in the aqueous cosmetics. The analysis was performed on gas chromatography coupled with a flame ionization detection（GC-FID）. The mixed solution containing 30 μL of chloroform（extraction solvent） and 300 μL of tetrahydrofuran（dispersive solvent） was rapidly injected into the sample solution for the purpose of microextraction. After that, the solution mentioned above was centrifuged at 4000 r/min for 10 min, and then the organic sediment phase was detected by GC-FID. The effects of experimental parameters, such as the extraction solvent and the volume of it, and the dispersive solvent and the volume of it, on the yield of the extraction were studied in detail. Under the optimum conditions, the enrichment factors of the target analytes range from 87 to 214. Linearity ranges are 0.05-10.0μg/mL for methylparaben and 0.025--5.0 μg/mL for the other five parabens. The relative standard deviations（RSDs） are lower than 8.2%（n=6）. The proposed method was applied to the analysis of six parabens in eleven aqueous cosmetics. The recoveries of the target analytes in the spiked real samples are in the range of 81.0%-103%.

基于低共熔溶剂的液液微萃取技术测定食用油中的新烟碱类杀虫剂

利用合成的低共熔溶剂(deep eutectic solvent,DES)作为液液微萃取技术中的萃取剂,利用超声波辅助分散,建立高效液相色谱测定食用油中4种新烟碱类杀虫剂(噻虫嗪、吡虫啉、啶虫脒、噻虫啉)的方法。首先将合成的DES加入到含有目标分析物的食用油(正己烷稀释)中,进行超声辅助分散加速提取,然后离心,吸出上层液体,再用微量注射器吸取DES富集相(下层)进行液相色谱分析。根据单一变量法,对影响萃取效率的一些因素进行优化,如DES的种类和体积、超声萃取时间、离心时间等。在最佳条件下,回收率在81.9%~98.0%之间,相对标准偏差为5.5%~8.3%(n=5),检出限范围为3.2~5.3μg/L,定量限范围为10.8~17.7μg/L。并且应用所建立的基于DES超声辅助分散液液微萃取方法检测食用油实际样品大豆油、葵花籽油、亚麻籽油中的新烟碱类农药。此方法提取和浓缩一步完成,避免了毒性较大的有机溶剂的使用,具有快速、简单、有效等显著优点。

固相微萃取新型吸附质丙烯酸丁酯-苯乙烯共聚物的研究与应用

研究了丙烯酸丁酯 -苯乙烯共聚物作为固相微萃取吸附质的性能及应用效果。对于水中芳烃化合物的定量测试结果表明该吸附质优良的特性。自制涂层与商品PDMS涂层比较 。

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），300μL 正己烷（萃取剂）；RP-LLME 为：25μL 0.16 mol / L NaOH（萃取剂）。最佳电泳条件：25 mmol / L NaH2 PO4，100 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 NaH2 PO4；压力进样20 s×20.67 kPa（3 psi）。PCP 和 TCP 的线性范围为0.5～100μg / L（ r≥0.9910）， DCP 的线性范围为1.5～80μg / L（r =0.9851）。3种分析物的检出限（ S / N =3）为0.035～0.114μg / 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。

固相微萃取吸附质苯乙烯—丙烯酸丁酯共聚物的合成与应用

本文合成了苯乙烯与丙烯酸丁酯共聚物,并进行了该聚合物作为固相微萃取(SPME)吸附质的应用实验,自制了(SPME)装置。考察了该涂层的热稳定性、单体比例与萃取率的关系。测试水中氯代烃的结果令人满意,通过与商品PA涂层比较,反映了本实验吸附质良好的特性。

苹果新品种‘瑞雪’及几个常见品种果实香气物质成分差异分析

【目的】以苹果新品种‘瑞雪’及其亲本‘粉红女士’和‘富士’以及代表性栽培品种‘嘎拉’‘乔纳金’‘金冠’‘王林’等7个品种为试验材料,分析果实成熟期香气物质成分的差异,探索苹果新品种‘瑞雪’的主要香气物质成分,为新品种的推广提供理论依据。【方法】应用顶空固相微萃取和气相色谱质谱联用技术,并结合主成分分析,解析参试品种的香气成分。【结果】7个品种共检测出香气物质成分92种,其中:酯类53种、醛类12种、醇类6种、酮类4种、烯烃类9种以及其他类8种;参试品种共有的香气物质成分有:乙酸丁酯、丁酸丁酯、乙酸己酯、2-甲基丁酸-2-甲基丁酯、2-甲基丁酸己酯、己酸己酯、己醛、2-己烯醛、1,3-2甲基苯、ɑ-法尼烯等共10种;不同品种特征香气成分个数分别为‘:瑞雪’(10种)、‘金冠’(10种)、‘粉红女士’(9种)、‘嘎拉’(9种)、‘王林’(8种)、‘乔纳金’(7种)、‘富士’(6种);根据7个苹果品种中香气物质相对含量为数据源进行主成分分析将其分为三类:第一类为‘嘎拉’和‘粉红女士’,第二类为‘富士’、‘王林’和‘金冠’,第三类为‘瑞雪’和‘乔纳金’;不同苹果品种间香气成分种类和含量均存在差异,苹果香气成分可以作为苹果品种选育的评价指标之一。【结论】相较于其他品种‘,瑞雪’苹果中特征香气成分种类较多,香气物质成分中的2-甲基-丁酸己酯(15.24%)、2-己烯醛(17.65%)和ɑ-法尼烯(27.88%)相对含量较高,而2-甲基-1-丁基乙酸酯和乙酸己酯相对含量较低,这些香气物质成分可能是形成‘瑞雪’苹果独特风味的重要原因。