Development of a static and exhaustive extraction procedure for field passive preconcentration of chlorophenols in environmental waters with hollow fiber-supported liquid membrane

A static and exhaustive extraction mode of hollow fiber-supported liquid membrane was developed for field sample passive pretreatment of environmental water samples. The extraction device was prepared by immobilizing dihexyl ether in the wall of a polypropylene hollow fiber membrane (60 cm length, 50 μm wall thickness, and 280 μm id) as liquid membrane and filling the fiber lumen with 0.1 M NaOH as acceptor, and closing the two ends of the fiber with an aluminum foil. Passive extraction was conducted by immersing the device into 15 mL water samples modified with 0.01 M HCl and 20% m/v NaCl. Model analytes including 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol were transferred into acceptor with extraction efficiencies over 79% in 10 h at room temperature, and determined by high-performance liquid chromatography. The proposed method has the enrichment factor of 394-498 and LOD of 0.3-0.4 μg/L for the three chlorophenols. Humic acid and salinity in the environmentally relevant range had no significant influence on the extraction, and chlorophenols in various environmental waters were determined with spike recoveries between 71.6 and 120%. The static passive extraction nature benefited field sample pretreatment without power, whereas the exhaustive extraction mode effectively eliminated the sample matrix effects.     

Ionic liquid based three-phase liquid-liquid-liquid solvent bar microextraction for the determination of phenols in seawater samples

For the first time, an ionic liquid based three-phase liquid-liquid-liquid solvent bar microextraction (IL-LLL-SBME) was developed for the analysis of phenols in seawater samples. The ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]), was used as the intermediary solvent for LLL-SBME, enhancing the extraction efficiency for polar analytes. In the procedure, the analytes were extracted from the aqueous sample into the ionic liquid intermediary and finally, back-extracted into an aqueous acceptor solution in the lumen of the hollow fiber. The porous polypropylene membrane acted as a filter to prevent potential interfering materials from being extracted, and no additional cleanup was required. After extraction, the acceptor solution could be directly injected into a high-performance liquid chromatographic system for analysis. Six phenols, 2-nitrophenol, 4-chlorophenol, 2,3-dichlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol were selected here as model compounds for developing and evaluating the method. The most influential extraction parameters were evaluated, including the ionic liquid, the composition of donor solution and acceptor solution, the extraction time and the extraction temperature, the effect of ionic strength, and the agitation speed. Under the most favorable extraction parameters, the method showed good linearity (from 0.05-50 to 0.5-50 μg/L, depending on the analytes) and repeatability of extractions (RSD below 8.3%, n=5). The proposed method was compared to conventional three-phase LLL-SBME and ionic liquid supported hollow fiber protected three-phase liquid-liquid-liquid microextraction, and showed higher extraction efficiency. The proposed method was demonstrated to be a simple, fast, and efficient method for the analysis of phenols from environmental water samples.     

Direct determination of chlorophenols in water samples through ultrasound-assisted hollow fiber liquid–liquid–liquid microextraction on-line coupled with high-performance liquid chromatography

In this study we on-line coupled hollow fiber liquid–liquid–liquid microextraction (HF-LLLME), assisted by an ultrasonic probe, with high-performance liquid chromatography (HPLC). In this approach, the target analytes – 2-chlorophenol (2-CP), 3-chlorophenol (3-CP), 2,6-dichlorophenol (2,6-DCP), and 3,4-dichlorophenol (3,4-DCP) – were extracted into a hollow fiber (HF) supported liquid membrane (SLM) and then back-extracted into the acceptor solution in the lumen of the HF. Next, the acceptor solution was withdrawn on-line into the HPLC sample loop connected to the HF and then injected directly into the HPLC system for analysis. We found that the chlorophenols (CPs) could diffuse quickly through two sequential extraction interfaces – the donor phase – SLM and the SLM – acceptor phase – under the assistance of an ultrasonic probe. Ultrasonication provided effective mixing of the extracted boundary layers with the bulk of the sample and it increased the driving forces for mass transfer, thereby enhancing the extraction kinetics and leading to rapid enrichment of the target analytes. We studied the effects of various parameters on the extraction efficiency, viz. the nature of the SLM and acceptor phase, the compositions of the donor and acceptor phases, the fiber length, the stirring rate, the ion strength, the sample temperature, the sonication conditions, and the perfusion flow rate. This on-line extraction method exhibited linearity (r² ≥ 0.998), sensitivity (limits of detection: 0.03–0.05 μg L⁻¹), and precision (RSD% ≤ 4.8), allowing the sensitive, simple, and rapid determination of CPs in aqueous solutions and water samples with a sampling time of just 2 min.     

Preconcentration and Determination of Chlorophenols in Wastewater with Dispersive Liquid–Liquid Microextraction Using Hydrophobic Deep Eutectic Solvents

Abstract

Hydrophobic deep eutectic solvents (DESs) were synthesized and developed for the preconcentration of three chlorophenols from wastewater by dispersive liquid–liquid microextraction (DLLME). The analyte concentrations were determined by high-performance liquid chromatography (HPLC). The hydrophobic DESs were prepared with the combination of hydrogen bond donors of decanoic acid or octanoic acid with different hydrogen bond acceptors of quaternary ammonium salts of tetrabutylammonium chloride, tetraoctylammonium chloride, methyltrioctylammonium chloride, and tetraheptylammonium chloride). Following the study of the stability and characterization by Fourier transform infrared spectroscopy, the hydrophobic DESs were developed as extractants and employed for the removal of 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) from wastewater. Using hydrophobic DESs as the microextraction solvents, several key parameters were optimized, including the type and volume of the hydrophobic DES, pH, and time of the extraction procedure. Under the optimized conditions, good recoveries from 90.8% to 93.0% were obtained for the three chlorophenols. The limits of detection were less than 0.05?µg/mL with relative standard deviations between 1.8% and 3.1%. The method was applied for the isolation and determination of synthetic chlorophenols in wastewater.     

Evaluation of liquid-phase microextraction conditions for determination of chlorophenols in environmental samples using gas chromatography-mass spectrometry without derivatization

Determination of trace chlorophenols (CPs) in environmental samples has been evaluated using liquid-phase microextraction (LPME) coupled with gas chromatography-mass spectrometry (GC-MS) without derivatization. The LPME procedure used to extract CPs from water involved 15 microL 1-octanol as acceptor solution in a 5.0 cm polypropylene hollow fiber with an inner diameter of 600 microm and a pore size of 0.2 microm. Under the optimal extraction conditions, enrichment factors from 117 to 220 are obtained. The obtained linear range is 1-100 ng mL(-1) with r(2)=0.9967 for 2,4-dichlorophenol (2,4-DCP); 1-100 ng mL(-1) with r(2)=0.9905 for 2,4,6-trichlorophenol (2,4,6-TCP); 5-500 ng mL(-1) with r(2)=0.9983 for 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and 10-1000 ng mL(-1) with r(2)=0.9929 for pentachlorophenol (PCP). The limits of detection range from 0.08 to 2 ng mL(-1), which is comparable with the reported values (12-120 ng mL(-1)). Recoveries of CPs in various matrices exceed 85% with relative standard deviations of less than 10%, except for PCP in landfill leachate. The applicability of this method was examined to determine CPs in environmental samples by analyzing landfill leachate, ground water and soil. The 2,4-DCP and 2,4,6-TCP detected in the landfill leachate are 6.68 and 2.47 ng mL(-1). The 2,4,6-TCP detected in ground water is 2.08 ng mL(-1). All the studied CPs are detected in contaminated soil. The proposed method is simple, low-cost, less organic solvent used and can potentially be applied to analyze CPs in complex environmental matrices.     

Comparative studies on the oxidative dechlorination of chlorophenols by a superoxide complex

Transition Metal Chemistry - The chlorophenols (CPs), 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP), are potent environmental hazards. They can be...     

Application of liquid-liquid-liquid microextraction and ion-pair liquid chromatography coupled with photodiode array detection for the determination of chlorophenols in water

A method termed as liquid-liquid-liquid microextraction was utilized to extract chlorophenols from water. The extracted chlorophenols, present in anionic form, were then separated, identified, and quantitated by ion-pair high-performance liquid chromatography with photodiode array detection (HPLC/DAD). For trace chlorophenol determination using HPLC/DAD, the chlorophenolate anion provides a better ultraviolet spectrum for quantitative and qualitative analyses than does uncharged chlorophenol. This is due to the auxochromic effect of the phenolate anion. In the study, experimental conditions such as organic phase identity, acceptor phase volume, sample agitation, extraction time, acceptor phase NaOH concentration, donor phase HCl concentration, salt addition, and UV absorption wavelength were optimized. Relative standard deviations (RSD, 2.3-5.4%), coefficients of determination (r2 0.9994-0.9999), and detection limits (0.049-0.081 ng mL(-1)) of the proposed method were investigated under the selected conditions. The method was successfully applied to analyses of reservoir and tap water samples, and the relative recoveries of chlorophenols from the spiked reservoir and tap water samples were 94.1-100.4% and 87.8-101.2%, respectively. The proposed method is capable of identifying and quantitating each analyte to 0.5 ng mL(-1), confirming the HPLC/DAD technique to be quite robust for monitoring trace levels of chlorophenols in water samples.     

In situ encapsulation of laccase in nanofibers by electrospinning for development of enzyme biosensors for chlorophenol monitoring

A biosensor based on Trametes versicolor laccase (Lac) was developed for the determination of phenolic compounds. The biosensor was prepared by in situ electrospinning of a mixture of polyvinyl alcohol (PVA), Lac, PEO-PPO-PEO (F108) and gold nanoparticles (Au NPs), where F108 was used as an enzyme stabilizing additive and Au NPs was used to enhance the conductivity of the biosensor. Laser confocal scanning microscopy and electrochemical impedance spectroscopy proved that the enzyme was successfully encapsulated into the electrospun nanofibers. Under the optimal conditions, the lowest detection limit was found to be 0.04 μM (S/N = 3) for 2,4-DCP and the highest detection limit was found to be 12.10 μM for 4-CP. The sensitivity of the biosensor obtained in the linear range for chlorophenols followed the sequence 2,4-dichlorophenol (2,4-DCP) > 2,4,6-trichlorophenol (2,4,6-TCP) > 4-chlorophenol (4-CP). The sensing performance for chlorophenols was attributed to the suitable electrochemical interface of PVA/F108/Au NPs/Lac, resulting from biocompatibility, a high surface area-to-volume ratio (10.42 m(2) g(-1)) and superior mechanical properties of the electrospun nanofibers. The biosensor exhibited good repeatabilities of 7.6%, 2.8% and 9.0% (R.S.D.) and reproducibilities of 14.9%, 10.4% and 13.7% (R.S.D.) for 4-CP, 2,4-DCP and 2,4,6-TCP, respectively. Lac retained 65.8% of its initial activity after a 30-day storage period.     

中空纤维三相液相微萃取-高效液相色谱法测定环境水样中7种苯氧羧酸类除草剂

建立了利用中空纤维三相液相微萃取-高效液相色谱联用技术(HF-LPME-HPLC)同时测定环境水中痕量麦草畏(dicamba)、氟草烟(fluroxypyr)、4-氯苯氧乙酸(4-CPA)、2甲4氯(MCPA)、2,4-滴(2,4-D)、2,4-滴苯氧丁酸(2,4-DB)和2甲4氯苯氧丁酸(MCPB)等7种苯氧羧酸类除草剂的分析方法。考察了萃取剂﹑接受相和给出相pH值、萃取时间﹑搅拌速度和盐效应等对检测的影响,通过正交试验优化萃取条件,得到的最佳萃取条件为正辛醇作萃取剂,给出相pH为3,接受相pH为12,萃取30 min,搅拌速度400 r/min。结果表明7种除草剂在较宽的线性范围内线性良好,相关系数为0.9953～0.9988,检出限(信噪比为3)为0.2～1.0 μg/L,富集倍数为76.7～121,加标回收率为68%～104%,相对标准偏差为3.2%～8.1%。该法灵敏度高、操作简单、检测快速、有机溶剂消耗少,为环境水样中痕量苯氧羧酸类除草剂残留的分析提供了有益的参考。     

Development of a simple in-vial liquid-phase microextraction device for drug analysis compatible with capillary gas chromatography, capillary electrophoresis and high-performance liquid chromatography

A simple, inexpensive and disposable device for liquid-phase microextraction (LPME) is presented for use in combination with capillary gas chromatography (GC), capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). 1-4 ml samples of human urine or plasma were filled into conventional 4-ml vials, whereafter 15-25 microl of the extraction medium (acceptor solution) was filled into a short piece of a porous hollow fiber and placed into the sample vial. The drugs of interest were extracted from the sample solutions and into the small volumes of acceptor solution based on high partition coefficients and were preconcentrated by a factor of 30-125. For LPME in combination with GC, the porous hollow fiber was filled with 15 microl n-octanol as the acceptor solution. Following 30 min of extraction, the organic acceptor solution was injected directly into the GC system. For LPME in combination with CE and HPLC, n-octanol was immobilized within the pores of the hollow fiber, while the internal volume of the fiber was filled with either 25 microl of 0.1 M HCl (for extraction of basic compounds) or 25 microl 0.02 M NaOH (for acidic compounds). Following 45 min extraction, the aqueous acceptor solution was injected directly into the CE or HPLC system. Owing to the low cost, the extraction devices were disposed after a single extraction which eliminated the possibility of carry over effects. In addition, because no expensive instrumentation was required for LPME, 10-30 samples were extracted in parallel to provide a high number of samples per unit time capacity.     

Stir bar sorptive extraction with in situ derivatization and thermal desorption-gas chromatography-mass spectrometry for determination of chlorophenols in water and body fluid samples

A new method, stir bar sorptive extraction (SBSE) with in situ derivatization and thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS), which is used for the determination of trace amounts of chlorophenols, such as 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TrCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP) and pentachlorophenol (PCP), in tap water, river water and human urine samples, is described. The derivatization conditions with acetic acid anhydride and the SBSE conditions such as extraction time are investigated. Then, the stir bar is subjected to TD followed by GC-MS. The detection limits of the chlorophenols in tap water, river water and human urine samples are 1-2, 1-2, and 10-20 pg ml⁻¹ (ppt), respectively. The calibration curves for the chlorophenols are linear and have correlation coefficients higher than 0.99. The average recoveries of the chlorophenols in all the samples are higher than 95% (R.S.D. < 10%) with correction using added surrogate standards, 2,4-dichlorophenol-d₅, 2,4,6-trichlorophenol-¹³C₆, 2,3,4,6-tetrachlorophenol-¹³C₆ and pentachlorophenol-¹³C₆. This simple, accurate, sensitive and selective analytical method may be applicable to the determination of trace amounts of chlorophenols in liquid samples.     

Quantitative determination of chlorophenols in leather by pressurized liquid extraction and liquid chromatography with diode-array detection

Pressurized liquid extraction (PLE) with acetonitrile was used for the recovery of chlorophenols (4-chloro-3-methylphenol, 4-chloro-2-methylphenol, 2,4-dichlorophenol, 2-phenylphenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol) present as biocides in leather. After a single cycle PLE treatment, solutions underwent pre-concentration by evaporation of the solvent under vacuum and clean-up treatment with solid-phase extraction cartridges. Quantitative analysis of the target compounds was carried out by liquid chromatography with gradient elution and UV spectrophotometric detection at variable wavelength for the various analytes in the range 190-240 nm. Instrumental detection limits and operative detection limits in the real matrices were determined according to the Hubaux-Vos approach and to the US Environmental Protection Agency procedures. The detection limits for the seven analytes ranged from 10 to 70 microg kg(-1). Linearity was very good in the explored range (10(-7)-10(-5)M) giving R(2) values from 0.995 to 1.000 for pentachlorophenol and 2,4-dichlorophenol, respectively. Repeatability was satisfactory, 2-5% for a 1 x 10(-6)M level of concentration, on five repeated measurements on the sample. Recovery yield values with the proposed procedure were determined using spiked samples. Overall recovery ranged from 88 to 97%. The method was used for routine analysis of real leather samples.     

A new high-speed hollow fiber based liquid phase microextraction method using volatile organic solvent for determination of aromatic amines in environmental water samples prior to high-performance liquid chromatography

A new and fast hollow fiber based liquid phase microextraction (HF-LPME) method using volatile organic solvents coupled with high-performance liquid chromatography (HPLC) was developed for determination of aromatic amines in the environmental water samples. Analytes including 3-nitroaniline, 3-chloroaniline and 4-bromoaniline were extracted from 6 mL basic aqueous sample solution (donor phase, NaOH 1 mol L⁻¹) into the thin film of organic solvent that surrounded and impregnated the pores of the polypropylene hollow fiber wall (toluene, 20 μL), then back-extracted into the 6 μL acidified aqueous solution (acceptor phase, HCl 0.5 mol L⁻¹) in the lumen of the two-end sealed hollow fiber. After the extraction, 5 μL of the acceptor phase was withdrawn into the syringe and injected directly into the HPLC system for the analysis. The parameters influencing the extraction efficiency including the kind of organic solvent and its volume, composition of donor and acceptor phases and the volume ratio between them, extraction time, stirring rate, salt addition and the effect of the analyte complexation with 18-crown-6 ether were investigated and optimized. Under the optimal conditions (donor phase: 6 mL of 1 mol L⁻¹ NaOH with 10% NaCl; organic phase: 20 μL of toluene; acceptor phase: 6 μL of 0.5 mol L⁻¹ HCl and 600 m mol L⁻¹ 18-crown-6 ether; pre-extraction and back-extraction times: 75 s and 10 min, respectively; stirring rate: 800 rpm), the obtained EFs were between 259 and 674, dynamic linear ranges were 0.1-1000 μg L⁻¹ (R > 0.9991), and also the limits of detection were in the range of 0.01-0.1 μg L⁻¹. The proposed procedure worked very well for real environmental water samples with microgram per liter level of the analytes, and good relative recoveries (91-102%) were obtained for the spiked sample solutions.     

Determination of chlorophenols in landfill leachate using headspace sampling with ionic liquid-coated solid-phase microextraction fibers combined with gas chromatography–mass spectrometry

A new microextraction technique based on ionic liquid solid-phase microextraction (IL-SPME) was developed for determination of trace chlorophenols (CPs) in landfill leachate. The synthesized ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C₄MIM][PF₆]), was coated onto the spent fiber of SPME for extraction of trace CPs. After extraction, the absorbed analytes were desorbed and quantified using gas chromatography–mass spectrometry (GC/MS). The term of the proposed method is as ionic liquid-coated of solid-phase microextraction combined with gas chromatography–mass spectrometry (IL-SPME-GC/MS). No carryover effect was found, and every laboratory-made ionic liquids-coated-fiber could be used for extraction at least eighty times without degradation of efficiency. The chlorophenols studied were 2,4-dichlorophenol (2,4-DP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and pentachlorophenol (PCP). The best results of chlorophenols analysis were obtained with landfill leachate at pH 2, headspace extraction for 4 min, and thermal desorption with the gas chromatograph injector at 240 °C for 4 min. Linearity was observed from 0.1 to 1000 μg L⁻¹ with relative standard deviations (RSD) less than 7% and recoveries were over 87%. The limit of detection (LOD) for pentachlorophenol was 0.008 μg L⁻¹. The proposed method was tested by analyzing landfill leachate from a sewage farm. The concentrations of chlorophenols were detected to range from 1.1 to 1.4 μg L⁻¹. The results demonstrate that the IL-SPME-GC/MS method is highly effective in analyzing trace chlorophenols in landfill leachate.     

Hollow‐fiber‐supported liquid membrane microextraction of amlodipine and atorvastatin

A simple, environmentally friendly, and efficient method, based on hollow‐fiber‐supported liquid membrane microextraction, followed by high‐performance liquid chromatography has been developed for the extraction and determination of amlodipine (AML) and atorvastatin (ATO) in water and urine samples. The AML in two‐phase hollow‐fiber liquid microextraction is extracted from 24.0 mL of the aqueous sample into an organic phase with microliter volume located inside the pores and lumen of a polypropylene hollow fiber as acceptor phase, but the ATO in three‐phase hollow‐fiber liquid microextraction is extracted from aqueous donor phase to organic phase and then back‐extracted to the aqueous acceptor phase, which can be directly injected into the high‐performance liquid chromatograph for analysis. The preconcentration factors in a range of 34–135 were obtained under the optimum conditions. The calibration curves were linear (R² ≥ 0.990) in the concentration range of 2.0–200 μg/L for AML and 5.0–200 μg/L for ATO. The limits of detection for AML and ATO were 0.5 and 2.0 μg/L, respectively. Tap water and human urine samples were successfully analyzed for the existence of AML and ATO using the proposed methods.     

Automated dynamic liquid-liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection for the determination of phenoxy acid herbicides in environmental waters

Automated dynamic liquid-liquid-liquid microextraction (D-LLLME) controlled by a programmable syringe pump and combined with HPLC-UV was investigated for the extraction and determination of 5 phenoxy acid herbicides in aqueous samples. In the extraction procedure, the acceptor phase was repeatedly withdrawn into and discharged from the hollow fiber by the syringe pump. The repetitive movement of acceptor phase into and out of the hollow fiber channel facilitated the transfer of analytes into donor phase, from the organic phase held in the pore of the fiber. Parameters such as the organic solvent, concentrations of the donor and acceptor phases, plunger movement pattern, speed of agitation and ionic strength of donor phase were evaluated. Good linearity of analytes was achieved in the range of 0.5-500 ng/ml with coefficients of determination, r2 > 0.9994. Good repeatabilities of extraction performance were obtained with relative standard deviations lower than 7.5%. The method provided up-to 490-fold enrichment within 13 min. In addition, the limits of detection (LODs) ranged from 0.1 to 0.4 ng/mL (S/N = 3). D-LLLME was successfully applied for the analysis of phenoxy acid herbicides from real environmental water samples.     

三相中空纤维膜液相微萃取-高效液相色谱法测定水中痕量双酚A

建立了三相中空纤维膜液相微萃取-高效液相色谱(HF-LPME-HPLC)方法,用于分析测定水中痕量双酚A的含量.设计了三相中空纤维膜液相微萃取系统,优化的HP-LPME最佳萃取条件为:萃取剂为正辛醇,接受相NaOH浓度为0.09 mol/L,样品溶液pH=4.0,NaC1加入量为30 g/L,搅拌速度为900 r/min,萃取时间为60 min.萃取后取20 μL接受相进行色谱分析.在最佳萃取条件下,方法的线性范围为0.5～200 μg/L(r＞ 0.999),检出限(信噪比为3)为0.2 μg/L;富集因子为241;方法RSD＜3.2％ (n=3).在实际环境水样中添加5,20和50μg/L的双酚A标准物质,加标平均回收率为92.8％～101.9％.表明本方法可用于水中痕量双酚A的快速准确测定.     

Faster and simpler determination of chlorophenols in water by fiber introduction mass spectrometry

Solid phase microextraction (SPME) of chlorophenols [2-chlorophenol (2CP), 2,4-dichlorophenol (24CP), 4-chloro-3-methylphenol (43CP), 2,4,6-tri-chlorophenol (246CP) and pentachlorophenol (PCP)] followed by direct mass spectrometric analysis has been performed by fiber introduction mass spectrometry (FIMS). Two SPME fibers (65 μm PDMS/DVB and 85 μm PA fibers) were tested, and FIMS was performed via selective ion monitoring (SIM). The extractions were evaluated at 10% ionic strength and pH 1. Best extraction times were determined for both fibers. Limits of detection (LOD) and limits of quantification (LOQ) for both fibers were in the low μg L⁻¹ range. Coefficients of correlation for the analytical curves showed linear responses and mineral water and river water samples spiked with 50 μg L⁻¹ presented high recoveries. FIMS, as compared to current EPA methods, is demonstrated to allow faster and simpler (elimination of pre-separation or derivatization steps) analysis of chlorophenols in water with the required sensitivity.     

中空纤维液相微萃取-高效液相色谱法测定纺织品中10种含氯苯酚类化合物

建立了中空纤维液相微萃取-高效液相色谱法测定纺织品中10种含氯苯酚类化合物的方法。系统地优化了影响萃取效率的因素,得到的最佳萃取条件为：萃取溶剂为正己烷,接受相NaOH溶液的浓度为0.10 mol/L,萃取时间为60 min,搅拌速度为600 r/min。在最佳萃取条件下,10种含氯苯酚在0.01～1.00 mg/L范围内线性关系良好（r>0.999）,10种含氯苯酚的检出限（信噪比为3）为0.01 mg/kg,富集倍数为95～101。在空白样品中添加0.01、0.05和0.1 mg/kg 3个不同水平的10种含氯苯酚类化合物,其平均回收率为78.8%～105.1%,相对标准偏差为0.3%～7.3%。研究结果表明该方法灵敏度高、简便、准确,可用于纺织品中含氯苯酚类化合物的测定。     

Liquid–liquid–liquid microextraction of degradation products of nerve agents followed by liquid chromatography–tandem mass spectrometry

Alkyl alkylphosphonic acids (AAPAs) are important environmental markers of nerve agents. A simple hollow fiber-based liquid–liquid–liquid microextraction (HFLLLME) technique has been developed to enrich the AAPAs from water. AAPAs were extracted from acidified aqueous phase to organic phase present in pores of the hollow fiber, and then back extracted into the alkaline acceptor phase present in the lumen of the hollow fiber. Variables affecting the HFLLLME process were optimized using a Plackett–Burman design and a Doehlert design. Optimal experimental conditions were: organic solvent, 1-octanol; pH of acceptor phase, 14; extraction time, 60 min; pH of donor phase, 1; and NaCl concentration, 10% (w/v). Depending upon the alkyl substituent, lower limits of detection varied from 0.1 to 100 ng mL⁻¹ (S/N ≥ 5). Repeatability of the method was observed with relative standard deviation of 1.49–9.83% (n = 3). After validation, the method was applied to detect AAPAs present in the water sample provided by the Organization for Prohibition of Chemical Weapons (OPCW) during the 23rd official proficiency test. The added advantage of this method is that several successive extractions of AAPAs from the same water sample can be performed.