Determination of organic pollutants in coking wastewater by dispersive liquid–liquid microextraction/GC/MS

A method based on dispersive liquid–liquid microextraction coupled with GC/MS was developed for quantitative analysis of the major organic pollutants listed in the United States Environmental Protection Agency method 8270 and the 15 European‐priority polycyclic aromatic hydrocarbons in coking wastewater. The major parameters such as extraction solvent, dispersive solvent, solution pH, and extraction time were systematically optimized. The optimum extraction conditions were found to be: 15 μL mixture of 2:1 v/v carbon tetrachloride and chlorobenzene as the extraction solvent, 0.75 mL ACN as the dispersive solvent, solution pH of 8, and extraction time of 2 min. For the major pollutants listed in the United States Environmental Protection Agency 8270, the linear ranges were 0.1 to 100 mg/L, the enrichment factors ranged from 452 to 685, and the relative recoveries ranged from 67.5 to 103.5% with RSDs of 4.0–9.1% (n = 5) at the concentrations of 10 mg/L under the optimum extraction conditions. For the 15 polycyclic aromatic hydrocarbons, the linear ranges were 0.1 to 100 μg/L, the enrichment factors ranged from 645 to 723, and the relative recoveries ranged from 94.5 to 107.6% with RSDs of 4.6–9.0% (n = 5) at the concentrations of 10 μg/L. The usefulness of the developed method was demonstrated by applying it in the analysis of real‐world coking wastewater samples.     

基于分子络合的分散液液微萃取与高效液相色谱联用检测环境水样中2种苯氧羧酸类除草剂

建立了基于分子络合的分散液液微萃取（DLLME）方法,以磷酸三丁酯为萃取剂,以甲醇为分散剂,与高效液相色谱联用检测了环境水样中麦草畏和2,4-二氯苯氧乙酸（2,4-D酸）2种苯氧羧酸类除草剂,对影响前处理效果的因素（包括水样的pH值、萃取剂的种类和体积、分散剂的种类和体积、反萃液的pH值、反萃液的体积和盐浓度等）进行了详细考察,在最佳萃取条件下（水样体积10 mL,水样的pH值为0~1.0、100 μL磷酸三丁酯萃取剂、1000 μL甲醇分散剂、0.01 mol/L的氢氧化钾反萃液的体积为80 μL）,2种苯氧羧酸类除草剂在0.50~1000 μg/L范围内具有良好的线性,相关系数不小于0.9985,麦草畏和2,4-D酸的检出限分别为0.44 μg/L和0.49 μg/L,富集倍数分别为85和90,在实际样品中的加标回收率为75.7%~104.0%。该方法基于分子络合反应机理,将新型萃取剂磷酸三丁酯应用于分散液液微萃取,与HPLC联用实现了麦草畏和2,4-D酸的富集与检测,为环境水样中苯氧羧酸类除草剂的检测提供了新的前处理方法。     

Preconcentration and determination of methyl methacrylate by dispersive liquid–liquid microextraction

This article describes the preconcentration of methyl methacrylate in produced water by the dispersive liquid–liquid microextraction using extraction solvents lighter than water followed by gas chromatography. In the present experiments, 0.4 mL dispersive solvent (ethanol) containing 15.0 μL extraction solvent (toluene) was rapidly injected into the samples and followed by centrifuging and direct injection into the gas chromatograph equipped with flame ionization detector. The parameters affecting the extraction efficiency were evaluated and optimized including toluene (as extraction solvent), ethanol (as dispersive solvent), 15 μL and 0.4 mL (as the volume of extraction and dispersive solvents, respectively), pH 7, 20% ionic strength, and extraction's temperature and time of 20°C and 10 min, respectively. Under the optimum conditions, the figures of merits were determined to be LOD = 10 μg/L, dynamic range = 20–180 μg/L, RSD = 11% (n = 6). The maximum recovery under the optimized condition was determined to be 79.4%.     

A rapid MCM‐41 dispersive micro‐solid phase extraction coupled with LC/MS/MS for quantification of ketoconazole and voriconazole in biological fluids

A rapid dispersive micro‐solid phase extraction (D‐μ‐SPE) combined with LC/MS/MS method was developed and validated for the determination of ketoconazole and voriconazole in human urine and plasma samples. Synthesized mesoporous silica MCM‐41 was used as sorbent in d ‐μ‐SPE of the azole compounds from biological fluids. Important D‐μ‐SPE parameters, namely type desorption solvent, extraction time, sample pH, salt addition, desorption time, amount of sorbent and sample volume were optimized. Liquid chromatographic separations were carried out on a Zorbax SB‐C₁₈ column (2.1 × 100 mm, 3.5 μm), using a mobile phase of acetonitrile–0.05% formic acid in 5 mm ammonium acetate buffer (70:30, v /v). A triple quadrupole mass spectrometer with positive ionization mode was used for the determination of target analytes. Under the optimized conditions, the calibration curves showed good linearity in the range of 0.1–10,000 μg/L with satisfactory limit of detection (≤0.06 μg/L) and limit of quantitation (≤0.3 μg/L). The proposed method also showed acceptable intra‐ and inter‐day precisions for ketoconazole and voriconazole from urine and human plasma with RSD ≤16.5% and good relative recoveries in the range 84.3–114.8%. The MCM‐41‐D‐μ‐SPE method proved to be rapid and simple and requires a small volume of organic solvent (200 μL); thus it is advantageous for routine drug analysis.     

Optimization of dispersive liquid-liquid microextraction and improvement of detection limit of methyl tert-butyl ether in water with the aid of chemometrics

Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry-selective ion monitoring (GC-MS-SIM) was applied to the determination of methyl tert-butyl ether (MTBE) in water samples. The effect of main parameters affecting the extraction efficiency was studied simultaneously. From selected parameters, volume of extraction solvent, volume of dispersive solvent, and salt concentration were optimized by means of experimental design. The statistical parameters of the derived model were R(2)=0.9987 and F=17.83. The optimal conditions were 42.0 μL for extraction solvent, 0.30 mL for disperser solvent and 5% (w/v) for sodium chloride. The calibration linear range was 0.001-370 μg L(-1). The improved detection limit with the aid of chemometrics was 0.3 ng L(-1). The relative standard deviation (RSD) with n=9 for 0.1 mg L(-1) MTBE in water with and without internal standard was 2.7% and 3.1%, respectively. Under the optimal conditions, the relative recoveries of spiked MTBE in different water samples were in the range of 100-105%.     

Efficient sample preparation method based on solvent‐assisted dispersive solid‐phase extraction for the trace detection of butachlor in urine and waste water samples

In this work, an efficient sample preparation method termed solvent‐assisted dispersive solid‐phase extraction was applied. The used sample preparation method was based on the dispersion of the sorbent (benzophenone) into the aqueous sample to maximize the interaction surface. In this approach, the dispersion of the sorbent at a very low milligram level was achieved by inserting a solution of the sorbent and disperser solvent into the aqueous sample. The cloudy solution created from the dispersion of the sorbent in the bulk aqueous sample. After pre‐concentration of the butachlor, the cloudy solution was centrifuged and butachlor in the sediment phase dissolved in ethanol and determined by gas chromatography with flame ionization detection. Under the optimized conditions (solution pH = 7.0, sorbent: benzophenone, 2%, disperser solvent: ethanol, 500 μL, centrifuged at 4000 rpm for 3 min), the method detection limit for butachlor was 2, 3 and 3 μg/L for distilled water, waste water, and urine sample, respectively. Furthermore, the preconcentration factor was 198.8, 175.0, and 174.2 in distilled water, waste water, and urine sample, respectively. Solvent‐assisted dispersive solid‐phase extraction was successfully used for the trace monitoring of butachlor in urine and waste water samples.     

Central composite design optimization of dispersive liquid–liquid microextraction based on solidification of organic drop for the determination of 5-hydroxymethyl-2-furfural in orange juice using high-performance liquid chromatography

A simple, rapid and inexpensive dispersive liquid–liquid microextraction based on solidification of organic drop combined with HPLC was developed for the extraction and determination of trace levels of 5-hydroxymethyl-2-furfural in fruit juice. Effect of variables such as extracting and dispersive solvent volume and pH were investigated simultaneously using experimental design. Under the optimum conditions, the calibration graph was linear in the range of 1?200 μg/L with the detection limit of 0.3 μg/L. The optimized method revealed a good precision with relative standard deviation of 2.2%.The performance of the method was evaluated for extraction and determination of 5-hydroxymethyl-2-furfural in orange juice sample.     

Pressurized Liquid Extraction Combined with Dispersive Liquid‐liquid Micro‐extraction as an Efficient Sample Preparation Method for Determination of Volatile Components in Tobacco

The pressurized liquid extraction (PLE) followed by dispersive liquid–liquid micro‐extraction (DLLME) has been developed for extraction of volatile components in tobacco. 35 volatile components were detected by gas chromatography mass spectrometry (GC‐MS). Methanol–methyl tert‐butyl ether (MTBE) (8:2, v/v) was selected as PLE extraction solvent. The optimized DLLME procedure, 3 mL of pure water and 1.0 mL tobacco extract solution, 40 μL of chloroform as extraction solvent, 0.5 mL of acetonitrile as disperser solvent, was validated. Under the optimum conditions, the enrichment factors were in the range of 96‐159. The limits of detection were between 0.14 and 0.33 μg/kg. The repeatability of the proposed method, expressed as relative standard deviation, varied between 4.3 and 7.5% (n = 6). The recoveries of the analytes evaluated by fortification of tobacco samples were in the range of 84.7‐96.4%. Compared with the conventional sample preparation method for determination of volatile components in tobacco, the proposed method was quick and easy to operate, and had high‐enrichment factors and low consumption of organic solvent.     

Trace determination of dichlorvos in environmental samples by room temperature ionic liquid-based dispersive liquid-phase microextraction combined with HPLC

Using 1-butyl-3-methylimidazolium hexa?uorophosphate ([BMIM][PF6]) room temperature ionic liquid (RTIL) as extraction solvent, tetrahydrofuran (THF) as disperser solvent, the organophosphorus pesticide dichlorvos in water was determined by dispersive liquid-liquid microextraction (DLLME) combined with high-performance liquid chromatography. Factors affecting RTIL-DLLME (type of disperser solvent, amount of RTIL, volume of disperser solvent, percentage of NaCl and volume and pH of water sample) were optimized by the single-factor method, obtaining the most favorable results when using 65 μL of [BMIM][PF6] and 260 μL of THF to extract the compound from an 8-mL water sample at pH 5.0 containing 25% (w/v) of NaCl. Under these optimum conditions, an enrichment factor of 215-fold was obtained. The calibration curves were linear in the concentration range of 2-1,000 μg/L. The limit of detection calculated at a signal-to-noise ratio of 3 was 0.2 μg/L. The relative standard deviations (RSD) for six replicate experiments at 20, 100 and 200 μg/L concentration levels were 1.8%, 1.3% and 1.3 %, respectively. Then the proposed method was applied to the analysis of three different water sample sources (tap, farm and rain water) and the relative recoveries and RSD of spiked water samples were 95.6-102.4% and 0.6-3.1%, respectively, at three different concentration levels of 20, 100 and 200 μg/L.     

Utilization of homogeneous liquid–liquid extraction followed by HPLC-UV as a sensitive method for the extraction and determination of phthalate esters in environmental water samples

A simple and sensitive method for the extraction of four phthalate esters including dimethyl phthalate (DMP), diethyl phthalate (DEP), benzyl butyl phthalate (BBP) and di-n-butyl phthalate (DBP) as well as their determination in water samples was developed using homogeneous liquid–liquid extraction (HLLE) and HPLC-UV. The extraction method is based on the phase separation phenomenon by the salt addition to the ternary solvent system. The extraction parameters such as type and volume of extracting and consolute solvent, concentration of salt, pH of sample and extraction time were optimized. Under the optimal conditions (extraction solvent: 100?µL CHCl₃; consolute solvent: 2.0?mL methanol; NaCl 15% (w/v) and pH of sample: 6.5) extraction recovery was in the range of 92–102%. Linearity was observed in the range of 0.5–300?µg?L^?1 for DEP and 0.6–300?µg?L^?1 for DMP, BBP and DBP. Correlation coefficients (r ²), limits of detection (LODs) and relative standard deviations (RSDs) were in the ranges of 0.9976–0.9993, 0.18–0.25 and 1.5–4.8%, respectively. The method was successfully applied for the preconcentration and determination of these phthalate esters in the several environmental water samples.     

Simultaneous derivatization and air‐assisted liquid–liquid microextraction of some parabens in personal care products and their determination by GC with flame ionization detection

A simultaneous derivatization/air‐assisted liquid–liquid microextraction technique has been developed for the sample pretreatment of some parabens in aqueous samples. The analytes were derivatized and extracted simultaneously by a fast reaction/extraction with butylchloroformate (derivatization agent/extraction solvent) from the aqueous samples and then analyzed by GC with flame ionization detection. The effect of catalyst type and volume, derivatization agent/extraction solvent volume, ionic strength of aqueous solution, pH, numbers of extraction, aqueous sample volume, etc. on the method efficiency was investigated. Calibration graphs were linear in the range of 2–5000 μg/L with squared correlation coefficients >0.990. Enhancement factors and enrichment factors ranged from 1535 to 1941 and 268 to 343, respectively. Detection limits were obtained in the range of 0.41–0.62 μg/L. The RSDs for the extraction and determination of 250 μg/L of each paraben were <4.9% (n = 6). In this method, the derivatization agent and extraction solvent were the same and there is no need for a dispersive solvent, which is common in a traditional dispersive liquid–liquid microextraction technique. Furthermore, the sample preparation time is very short.     

液相微萃取-高效液相色谱法快速测定唾液中尼古丁含量

建立了一种以液相微萃取为样品前处理技术,结合高效液相色谱快速、有效测定唾液中尼古丁含量的方法。确定了以磷酸三丁酯为有机溶剂、2 mL 0.05 mol/L KOH调节2 mL样品溶液为给出相,10 mmol/LKH2PO4(pH=3.0)为接收相;搅拌速率为500 r/min,萃取时间为17 min的尼古丁优化萃取条件。方法的线性范围0.1-50 mg/L,相关系数r2=0.9996;检出限为0.05 mg/L(S/N=3);相对标准偏差<5%(n=5);相对回收率为96.3%-102.2%。实验证明该法可用于唾液等生物体液中碱性物质的测定。     

分散固相萃取-分散液液微萃取/高效液相色谱法测定西瓜中氟唑菌酰羟胺残留

采用分散固相萃取和分散液液微萃取联用的方法,建立了高效液相色谱快速检测西瓜中氟唑菌酰羟胺残留的分析方法。使用乙腈和水混合溶液作为萃取溶剂,经N-丙基-乙二胺硅烷(PSA)固相萃取吸附剂净化提取液,分散液液微萃取将目标物富集到1,1,2,2-四氯乙烷溶剂中,采用高效液相色谱进行分析。考察了萃取溶剂的种类与体积、分散剂体积及盐浓度等因素对分散液液微萃取萃取效率的影响。结果表明:分析物的质量浓度在0.01~5 mg/L范围内与峰面积的线性关系良好,相关系数(r)为0.999 9,定量下限(S/N=10)为0.01 mg/kg。加标水平为0.01、0.1、1 mg/kg时,平均回收率为89.2%~94.5%,相对标准偏差(n=5)为3.0%~8.7%。该方法简单、高效、灵敏度高,适用于西瓜中氟唑菌酰羟胺的残留检测。     

溶剂去乳化-悬浮固化分散液液微萃取-气相色谱-质谱联用测定水中的有机氯农药

建立了溶剂去乳化-悬浮固化分散液液微萃取技术结合气相色谱-质谱联用技术同时测定水样中8种有机氯农药的方法。以正十六烷作为萃取剂,将其与分散剂丙酮混合后,快速注入水样,获得乳化体系并完成萃取;然后加入丙酮作为去乳化剂破坏乳化体系,不需要经过离心即能使两相分层;经冰浴冷冻使其固化后,取出上层凝固的有机相(正十六烷)在室温下融化,取上清液进行GC-MS分析。考察了萃取剂、分散剂、去乳化剂的种类和体积,水样盐浓度和pH值对萃取效率的影响。结果表明,8种有机氯农药在0.025~2.00 μg/L范围内有良好的线性关系(r=0.9995~0.9999), 8种有机氯农药的检出限为0.012~0.024 μg/L,精密度为3.15%~4.53%,富集倍数为96~101。将该方法应用于农田池塘水的测定,加标回收率为96.77%~102.93%,精密度为2.68%~4.86%。方法快速灵敏,有机溶剂消耗少,对环境友好,操作简便,适用于水中有机氯农药的批量分析,并为实现其样品前处理的自动化提供了技术和方法学的支持。     

Extraction optimization of polycyclic aromatic hydrocarbons by alcoholic-assisted dispersive liquid-liquid microextraction and their determination by HPLC

A sensitive method for the extraction and determination of polycyclic aromatic hydrocarbons (PAHs) using alcoholic-assisted dispersive liquid-liquid microextraction (AA-DLLME) and HPLC was developed. The extraction procedure was based on alcoholic solvents for both extraction and dispersive solvents. The effective parameters (type and volume of extraction and dispersive solvents, amount of salt and stirring time) on the extraction recovery were studied and optimized utilizing factorial design (FD) and central composite design (CCD). The best recovery was achieved by FD using 2-ethyl-1-hexanol as the extraction solvent and methanol as the dispersive solvent. The results showed that volume of dispersive solvent and stirring time had no effect on the recovery of PAHs. The optimized conditions were 145 μL of 2-ethyl-1-hexanol as the extraction solvent and 4.2% w/v of salt (NaCl) in sample solution. The enrichment factors of PAHs were in the range of 310-325 with limits of detection of 0.002-0.8 ng/mL. The linearity was 0.01-800 ng/mL for different PAHs. The relative standard deviation (RSD) for intra- and inter-day of extraction of PAHs were in the range of 1.7-7.0 and 5.6-7.3, respectively, for five measurements. The method was also successfully applied for the determination of PAHs in environmental water samples.     

超声辅助分散液液微萃取-高效液相色谱测定护肤水中9种荧光增白剂

建立了超声辅助分散液液微萃取技术结合高效液相色谱配荧光检测器(UA-DLLME-HPLC-FLD)同时测定护肤水中9种荧光增白剂(FWAs)残留量的检测方法。考察了萃取剂的种类与体积、分散剂的种类与体积分数、盐效应、pH值、超声时间等因素对萃取效果的影响,确定最佳萃取条件:50μL三氯甲烷为萃取剂,250μL甲醇为分散剂,氯化钠用量为0.20 g,4 500 r/min离心2 min。在优化条件下,9种荧光增白剂在一定质量浓度范围内线性关系良好,相关系数均大于0.999 0,方法检出限(S/N=3)为0.06~4.20 mg/kg,定量下限(S/N≥10)为0.2~14.0 mg/kg,方法的平均回收率为84.3%~102.4%。该方法具有有机溶剂用量少、操作简单、快捷、灵敏等优点。     

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet followed by high-performance liquid chromatography with ultraviolet detection and liquid chromatography-tandem mass spectrometry for the determination of triclosan and 2,4-dichlorophenol in water samples

A novel, simple and efficient dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) technique coupled with high-performance liquid chromatography with ultraviolet detection (HPLC-UV) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of triclosan and its degradation product 2,4-dichlorophenol in real water samples. The extraction solvent used in this work is of low density, low volatility, low toxicity and proper melting point around room temperature. The extractant droplets can be collected easily by solidifying it at a lower temperature. Parameters that affect the extraction efficiency, including type and volume of extraction solvent and dispersive solvent, salt effect, pH and extraction time, were investigated and optimized in a 5 mL sample system by HPLC-UV. Under the optimum conditions (extraction solvent: 12 μL of 1-dodecanol; dispersive solvent: 300 of μL acetonitrile; sample pH: 6.0; extraction time: 1 min), the limits of detection (LODs) of the pretreatment method combined with LC-MS/MS were in the range of 0.002-0.02 μg L(-1) which are lower than or comparable with other reported approaches applied to the determination of the same compounds. Wide linearities, good precisions and satisfactory relative recoveries were also obtained. The proposed technique was successfully applied to determine triclosan and 2,4-dichlorophenol in real water samples.     

Rapid determination of bisphenol A in drinking water using dispersive liquid‐phase microextraction with in situ derivatization prior to GC‐MS

This paper described a novel approach for the determination of bisphenol A by dispersive liquid‐phase microextraction with in situ acetylation prior to GC‐MS. In this derivatization/extraction method, 500 μL acetone (disperser solvent) containing 30.0 μL chlorobenzene (extraction solvent) and 30.0 μL acetic anhydride (derivatization reagent) was rapidly injected into 5.00 mL aqueous sample containing bisphenol A and K₂CO₃ (0.5% w/v). Within a few seconds the analyte was derivatized and extracted at the same time. After centrifugation, 1.0 μL of sedimented phase containing enriched analyte was determined by GC‐MS. Some important parameters, such as type and volume of extraction and disperser solvent, volume of acetic anhydride, derivatization and extraction time, amount of K₂CO₃, and salt addition were studied and optimized. Under the optimum conditions, the LOD and the LOQ were 0.01, 0.1 μg/L, respectively. The experimental results indicated that there was linearity over the range 0.1–50 μg/L with coefficient of correlation 0.9997, and good reproducibility with RSD 3.8% (n = 5). The proposed method has been applied for the analysis of drinking water samples, and satisfactory results were achieved.     

Development and application of chemometric-assisted dispersive liquid-liquid microextraction for the determination of suspected fragrance allergens in water samples

A simple and green method based on dispersive liquid-liquid microextraction, mated to chemometrics and followed by mass spectrometric detection for the determination of suspected fragrance allergens in water samples is developed and assessed in this work. Volume of extraction and disperser solvent, pH, ionic strength, extraction time, sample volume, as well as centrifugation time were initially optimized in a fractional factorial design. The obtained significant factors were optimized by using a central composite design and the quadratic model between the dependent and the independent variables was built. The obtained optimal conditions were: aqueous sample of 3.8 mL, 100 μL chloroform, 1.40 mL acetone, 4 min centrifugation time, natural pH containing 5% (w/v) NaCl, and centrifugation speed 4000 rpm. Method proved to be linear over a wide range of concentration for all analytes with R(2) between 0.9807 and 0.9959. The repeatability and reproducibility of the proposed method, expressed as relative standard deviation, varied between 3-13% and 4-16%, respectively. The limits of detection ranged from 0.007 to 1.0 μg L(-1) . The recommended method was applied to water samples including baby bath as well as swimming pool water samples and was compared with a previously reported method.     

Polypyrrole‐magnetite dispersive micro‐solid‐phase extraction combined with ultraviolet‐visible spectrophotometry for the determination of rhodamine 6G and crystal violet in textile wastewater

Polypyrrole‐magnetite dispersive micro‐solid‐phase extraction method combined with ultraviolet‐visible spectrophotometry was developed for the determination of selected cationic dyes in textile wastewater. Polypyrrole‐magnetite was used as adsorbent due to its thermal stability, magnetic properties, and ability to adsorb Rhodamine 6G and crystal violet. Dispersive micro‐solid‐phase extraction parameters were optimized, including sample pH, adsorbent amount, extraction time, and desorption solvent. The optimum polypyrrole‐magnetite dispersive micro‐solid phase‐extraction conditions were sample pH 8, 60 mg polypyrrole‐magnetite adsorbent, 5 min of extraction time, and acetonitrile as the desorption solvent. Under the optimized conditions, the polypyrrole‐magnetite dispersive micro‐solid‐phase extraction with ultraviolet‐visible method showed good linearity in the range of 0.05–7 mg/L (R ² > 0.9980). The method also showed a good limit of detection for the dyes (0.05 mg/L) and good analyte recoveries (97.4–111.3%) with relative standard deviations < 10%. The method was successfully applied to the analysis of dyes in textile wastewater samples where the concentration found was 1.03 mg (RSD ±7.9%) and 1.13 mg/L (RSD ± 4.6%) for Rhodamine 6G and crystal violet, respectively. It can be concluded that this method can be adopted for the rapid extraction and determination of dyes at trace concentration levels.