Application of liquid-phase microextraction for the determination of phoxim in water samples by high performance liquid chromatography with diode array detector

A new method, which involves liquid-phase microextraction (LPME) followed by high performance liquid chromatography (HPLC) with diode array detector (DAD), was developed to determine phoxim in water sample. Experimental parameters affecting the extraction efficiency, such as extraction solvent, solvent volume, agitation speed of the sample and extraction time were investigated. Under the optimal extraction conditions, phoxim was found to yield a good linear calibration curve in the concentration range from 0.01 to 5 μg mL⁻¹. The limit of detection (LOD) is 10 ng mL⁻¹, and relative standard deviation (RSD) at the 100 ng mL⁻¹ levels is 8.4%. Lake water and tap water samples were successfully analyzed using the proposed method.     

液相微萃取-高效液相色谱法分析葡萄汁中多酚类化合物

建立了一种基于液相微萃取与高效液相色谱联用技术测定葡萄汁中鞣花酸、白藜芦醇和槲皮素的分析方法. 比较了单液滴液相微萃取和中空纤维液相微萃取两种萃取模式, 选择了单液滴液相微萃取作为3种多酚类化合物的液相微萃取模式. 考察了搅拌速度、萃取时间、料液相pH和料液相离子强度的影响. 鞣花酸、白藜芦醇和槲皮素的富集倍数分别为48.4、 79.4和155.8, 方法的线性范围为0.0050～5.0 μg/mL, 鞣花酸、白藜芦醇和槲皮素的检出限分别为0.015, 0.0020, 0.0080 μg/mL, 相对标准偏差分别为2.0%, 1.8%和1.7%. 用于实际样品葡萄汁的分析, 加标回收率在81.9%～102.3%之间.     

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.     

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.     

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.     

液-液-液微萃取-高效液相色谱法测定人尿液中的美沙酮

建立了液-液-液微萃取与高效液相色谱联用技术快速分析尿样中美沙酮的方法.对有机溶剂种类、体积、样品溶液的pH值、萃取时间、搅拌速度进行了优化.方法的线性范围为0.05～10 mg/L,检出限为0.025 mg/L,相对标准偏差小于5%.     

Optimization of temperature-controlled ionic liquid dispersive liquid phase microextraction combined with high performance liquid chromatography for analysis of chlorobenzenes in water samples

Temperature-controlled ionic liquid dispersive liquid phase microextraction (TCIL-DLPME) combined with high performance liquid chromatography-diode array detection (HPLC-DAD) was applied for preconcentration and determination of chlorobenzenes in well water samples. The proposed method used 1-butyl-3-methylimidazolium hexafluorophosphate ([C₄mim][PF₆]) as the extraction solvent. The effect of different variables on extraction efficiency was studied simultaneously using an experimental design. The variables of interest in the TCIL-DLPME were extraction solvent volume, salt effect, solution temperature, extraction time, centrifugation time, and heating time. The Plackett-Burman design was employed for screening to determine the variables significantly affecting the extraction efficiency. Then, the significant factors were optimized by using a central composite design (CCD) and the response surface equations were developed. The optimal experimental conditions obtained from this statistical evaluation included: extraction solvent volume, 75 μL; extraction time, 20 min; centrifugation time, 25 min; heating time, 4 min; solution temperature, 50 °C; and no addition of salt. Under optimal conditions, the preconcentration factors were between 187 and 298. The limit of detections (LODs) ranged from 0.05 μg L⁻¹ (for 1,2-dichlorobenzene) to 0.1 μg L⁻¹ (for 1,2,3-trichlorobenzene). Linear dynamic ranges (LDRs) of 0.5-300 and 0.5-500 μg L⁻¹ were obtained for dichloro- and trichlorobenzenes, respectively. The performance of the method was evaluated for extraction and determination of chlorobenzenes in well water samples in micrograms per liter and satisfactory results were obtained (RSDs < 9.2%).     

Ionic liquid-based single-drop liquid-phase microextraction combined with high-performance liquid chromatography for the determination of sulfonamides in environmental water

A simple, rapid and environment‐friendly technique of single‐drop liquid‐phase microextraction has been developed for the determination of sulfonamides in environmental water. Several important parameters including stirring rate, extraction solvent, extraction pH, salinity and extraction time were optimized to maximize the extract efficiency. Extraction solvent 1‐octyl‐3‐methylimidazolium hexafluorophosphate [C₈MIM][PF₆] ionic liquid showed better extraction efficiency than 1‐butyl‐3‐methylimidazolium hexafluorophosphate [C₄MIM][PF₆] and 1‐octanol. The optimum experimental conditions were: pH, 4.5; sodium chloride content, 36% w/v; extraction time, 20 min. This method provided low detection limits (0.5–1 ng/mL), good repeatability (the RSD ranging from 4.2 to 9.9%, n=5) and wide linear range (1–1500 ng/mL), with determination coefficients (r²) higher than 0.9989 for all the target compounds. Real sample analysis showed relative recoveries between 63.5 and 115.8% for all the target compounds.     

超声辅助分散液液微萃取-高效液相色谱测定水样中的4种邻苯二甲酸酯类增塑剂

建立了采用超声辅助分散液液微萃取技术结合高效液相色谱法(UA-DLLME-HPLC)对4种邻苯二甲酸酯(PAEs)进行富集、检测的方法,并成功应用于实际水样分析。实验中采用富集因子来评价萃取效率,考察并优化了影响萃取效率的主要因素,包括萃取剂类型和用量、分散剂类型和用量、超声时间、离子强度、萃取时间和pH值等。结果表明: 在最佳萃取条件下,该法对4种PAEs（邻苯二甲酸二甲酯、邻苯二甲酸二乙酯、邻苯二甲酸二丁酯和邻苯二甲酸二正辛酯）具有较高的富集能力,富集因子分别为71、144、169和159;检出限分别为3.78、1.77、3.07和3.30 μg/L。对实验室自来水、某品牌矿泉水以及湖水分别加标50、200及500 μg/L的回收率为82.99%～114.47%,相对标准偏差为1.93%～8.31%。该法简便、快速、环保,可以用于测定实际水样中的PAEs类增塑剂。     

Screening method for phthalate esters in water using liquid-phase microextraction based on the solidification of a floating organic microdrop combined with gas chromatography-mass spectrometry

A simple and efficient liquid-phase microextraction (LPME) technique was developed using directly suspended organic microdrop coupled with gas chromatography–mass spectrometry (GC–MS), for the extraction and the determination of phthalate esters (dimethyl phthalate, diethyl phthalate, diallyl phthalate, di-n-butyl phthalate (DnBP), benzyl butyl phthalate (BBP), dicyclohexyl phthalate and di-2-ethylhexyl phthalate (DEHP)) in water samples. Microextraction efficiency factors, such as nature and volume of the organic solvent, temperature, salt effect, stirring rate and the extraction time were investigated and optimized. Under the optimized extraction conditions (extraction solvent: 1-dodecanol; extraction temperature: 60 °C; microdrop volume: 7 μL; stirring rate: 750 rpm, without salt addition and extraction time: 25 min), figures of merit of the proposed method were evaluated. The values of the detection limit were in the range of 0.02–0.05 μg L⁻¹, while the R.S.D.% value for the analysis of 5.0 μg L⁻¹ of the analytes was below 7.7% (n = 4). A good linearity (r² ≥ 0.9940) and a broad linear range (0.05–100 μg L⁻¹) were obtained. The method exhibited enrichment factor values ranging from 307 to 412. Finally, the designed method was successfully applied for the preconcentration and determination of the studied phthalate esters in different real water samples and satisfactory results were attained.     

Emulsification liquid phase microextraction followed by on-line phase separation coupled to high performance liquid chromatography

An emulsification liquid phase microextraction followed by on-line phase separation coupled to high performance liquid chromatography (HPLC) is introduced based on a novel idea for the separation of dispersed organic phase from aqueous phase. In this method, the dispersed organic extraction phase was filtered using an in-line filter and it was separated from the water sample. The new approach is simple and, in addition to improving some limitations of the conventional emulsification liquid phase microextraction, eliminates the need for centrifugation in the phase separation step.     

Hollow fiber-based liquid phase microextraction combined with high-performance liquid chromatography for the analysis of gabapentin in biological samples

Three-phase hollow fiber microextraction technique combined with high performance liquid chromatography-ultra violet (HPLC-UV) was applied for the extraction and determination of gabapentin in biological fluids. Gabapentin (GBP) was derivatized with 1-fluoro-2,4-dinitrobenzene, as a UV absorbent agent in borate buffer (pH 8.2) before extraction. The derivative product of GBP was extracted from the 8.5 mL of acidic solution (source phase) into an organic phase (dihexyl ether) impregnated in the pores of a hollow fiber and finally back-extracted into 24 μL of the basic solution (pH 9.1) located inside the lumen of the hollow fiber (receiving phase). The extraction took place due to pH gradient between the inside and outside of the hollow fiber membrane. In order to achieve maximum extraction efficiency, different parameters affecting the extraction conditions were optimized. Under the optimized conditions, preconcentration factor of 95 and detection limit (LOD) of 0.2 μg L⁻¹ were obtained. The calibration graph was linear within the range of 0.6-5000 μg L⁻¹. Finally, the feasibility of the proposed method was successfully confirmed by extraction and determination of GBP in human urine and plasma samples in the range of microgram per liter and suitable results were obtained (RSDs < 6.3%).     

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...     

Optimization of ultrasound-assisted emulsification microextraction with solidification of floating organic droplet followed by high performance liquid chromatography for the analysis of phthalate esters in cosmetic and environmental water samples

Ultrasound-assisted emulsification microextraction with solidification of floating organic droplet (USAEME-SFO) followed by high performance liquid chromatography-diode array detection (HPLC-DAD), was applied for preconcentration and determination of phthalate esters in cosmetic and water samples. The effects of different variables on the extraction efficiency were studied simultaneously using an experimental design. The variables of interest in the USAEME-SFO were extraction solvent volume, salt effect, extraction time and centrifugation time. A factorial experimental design was employed for screening to determine the variables significantly affecting the extraction efficiency. Then, the significant factors were optimized by using a Box-Behnken design (BBD) and the response surface equations were derived. The optimum experimental conditions were extraction solvent volume, 30 μL; sodium chloride concentration, 20% (w/v); extraction time, 12 min and centrifugation time, 5 min. Under optimal conditions, the preconcentration factors were between 355 and 409. The limit of detections (LODs) ranged from 0.005 μg L⁻¹ (for Diethylphthalate) to 0.01 μg L⁻¹ (for Dimethylphthalate). Dynamic linear ranges; (DLRs) of 0.05-800 and 0.05-1000 μg L⁻¹ were obtained for Diisobutyl- and Dimethylphthalate, respectively. The performance of the method was evaluated for extraction and determination of phthalate esters in cosmetic and environmental water samples in micrograms per liter and satisfactory results were obtained (RSDs < 12.6%).     

Determination of ochratoxin A in wine using liquid-phase microextraction combined with liquid chromatography with fluorescence detection

A liquid-liquid microextraction technique (LPME) has been applied to the extraction of ochratoxin A (OTA) from wine prior to its quantification by HPLC-fluorescence detection. OTA was extracted from wine, through 1-octanol immobilized in the pores of a porous hollow fiber, and introduced into 1-octanol inside the fiber. Recovery was 77%. The method was adequate for quantification of OTA in wine at levels within the range 0.25-10 ng/ml with a LOD of 0.2 ng/ml, and can be a simple and inexpensive alternative to the use of inmunoaffinity columns in order to quantify OTA levels in wine.     

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.     

Determination of phthalate esters in cow milk samples using dispersive liquid-liquid microextraction coupled with gas chromatography followed by flame ionization and mass spectrometric detection

A simple and economic method for the analysis of phthalate esters, dimethyl phthalate, diethyl phthalate, di-iso-butyl phthalate, di-n-butyl phthalate, and di-2-ethylhexyl phthalate in cow milk samples by means of gas chromatography-flame ionization detection and gas chromatography-mass spectrometry has been developed. In this work, NaCl and ACN were added to 5 mL of the milk sample as the salting out agent and extraction solvent, respectively. After manual shaking, the mixture was centrifuged. In the presence of NaCl, a two-phase system was formed: upper phase - acetonitrile containing phthalate esters -and lower phase - aqueous phase containing soluble compounds and the precipitated proteins. After the extraction of phthalate esters from milk, a portion of supernatant phase (acetonitrile) was removed, mixed with 1,2-dibromoethane at microliter level and injected by syringe into NaCl solution. After the extraction of the selected phthalate esters into 1,2-dibromoethane, phase separation was performed by centrifugation and the enriched analytes in the sedimented phase were determined by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. Under the optimum extraction conditions, low limits of detection and quantification between 1.5-3 and 2.5-11 ng/mL, respectively was observed. Enrichment factors were in the range of 397-499. The relative standard deviations for the extraction of 100 ng/mL of each phthalate ester were in the range of 3-4% (n = 6). Finally, some milk samples were successfully analyzed using the proposed method and two analytes, di-n-butyl phthalate and di-2-ethylhyxel phthalate, were determined in them in nanogram per milliliter level.     

Carrier-mediated liquid phase microextraction coupled with high performance liquid chromatography for determination of illicit drugs in human urine

A new method was developed for the analysis of illicit drugs in human urine by coupling carrier-mediated liquid phase microextraction (LPME) to high performance liquid chromatography (HPLC). By adding an appropriate carrier in organic phase, simultaneous extraction and enrichment of hydrophilic (morphine and ephedrine) and hydrophobic (pethidine) drugs were achieved. Effects of the types of organic solvents and carriers, the carrier concentration in the organic phase, the HCl concentration in the acceptor solution, the stirring rate, and the extraction time on the enrichment factor of analytes were investigated. Under the optimal experimental conditions, high enrichment factors (202-515) were obtained. The linear detection ranges were 0.1-10 mg L⁻¹ for the studied drugs. The limits of detection (LOD) at signal-to-noise ratio of 3 were 0.05 mg L⁻¹ for both morphine and ephedrine, and 0.02 mg L⁻¹ for pethidine. This method was successfully applied to analysis of ephedrine in real urine specimens, revealing that the determination of illicit drugs in urine was feasible.     

固相微萃取-高效液相色谱联用测定环境水样中双酚A的自由溶解态浓度

应用可忽略耗损固相微萃取与高效液相色谱联用技术测定了环境水样中双酚A的自由溶解态浓度。为了获得高的灵敏度并减小环境因素（如温度和搅拌等）的影响,采用商品化固相微萃取纤维CW／TPR进行平衡采样。在环境水样常见pH（5～8）、缓冲容量（5～200mmol／L）和盐度（0～500mmol／L）条件下,4h可以达到萃取平衡。100mL样品足以避免样品耗损。以配制在250mmol／L NaCl和125mmol／L磷酸盐溶液（pH6．4）中的双酚A标准溶液进行校准,可以将缓冲液（0～200mmol／L）、盐度（0～500mmol／L）和pH（5．7～8．5）的影响控制在15％偏差范围以内。如需更准确的测定,也可以对样品pH值的影响加以校正。pH为6．4时,方法的线性范围为0．1～250μg／L,检出限为0．03μg／L,相对标准偏差（5μg/L,n=3）为1．1％。采用本方法测定了污水处理厂排水口的双酚A的自由溶解态浓度。     

Determination of aristolochic acid in urine using hollow fiber liquid-phase microextraction combined with high-performance liquid chromatography

A simple and efficient hollow fiber liquid‐phase microextraction (HF‐LPME) technique in conjunction with high‐performance liquid chromatography is presented for extraction and quantitative determination of aristolochic acid I in human urine samples. Several parameters influencing the efficiency of HF‐LPME were investigated and optimized, including extraction solvent, stirring rate, extraction time, pH of donor phase and acceptor phase. Excellent sample clean‐up was observed and good linearity with coefficient of 0.9999 was obtained in the range of 15.4–960 µg/L. This method provided a 230‐fold enrichment factor and good repeatability with relative standard deviations (RSD) lower than 6.0%. The limit of detection value for the analyte in urine sample was 0.01 µg/L at a signal‐to‐noise ratio of 3. The extraction recovery from urine samples was 61.8% with an RSD of 9.71%. Copyright © 2010 John Wiley & Sons, Ltd.