Application of LPME/GC-ECD for determination of PCP in water

PCP with a variety of application in industrial, agricultural and domestic fields, is an inhibitor of oxidative phosphorylation, therefore, toxic to a broad spectrum of organisms and may have mutagenic properties [1]. In China, sodium pentachlorophenate (Na-PCP) has been sprayed widely since the 1960s to control the spread of snailborne schistosomiasis. Although Na-PCP has been replaced by some new molluscicides since 1990s, the persistence of PCP has resulted in the accumulation in soil …     

Methods for determination of hexachlorobenzene and pentachlorophenol in soil samples

The efficiency of methods for the determination of hexachlorobenzene (HCB) and pentachlorophenol (PCP) in soil samples was evaluated. An on-line method was applied for HCB determination. Soil samples were transferred to chromatographic columns prepacked with alumina. The HCB elution was processed with n-hexane. The PCP was extracted from soil samples with n-hexane-acetone in an ultrasonic bath. After re-extraction with K(2)CO(3) solution PCP was acetylated with acetic anhydride. The pentachlorophenyl acetate derivative was then extracted with n-hexane. The HCB and PCP derivative were analyzed by gas chromatography with electron capture detection (GC-ECD). Mean recoveries obtained from soil samples fortified at levels of 0.5; 4 and 20 ng g(-1), ranged from 91 to 100% for HCB, and for PCP, at levels of 10; 40 and 200 ng g(-1), ranged from 88 to 101%. These results demonstrated the efficiency of the proposed methods.     

Optimisation of a dispersive liquid-liquid microextraction method for the simultaneous determination of halophenols and haloanisoles in wines

A dispersive liquid-liquid microextraction (DLLME) method has been optimised for simultaneously extracting 2,4,6-trichloranisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA), 2,4,6-tribromoanisole (TBA), pentachloroanisole (PCA), 2,4,6-trichlorophenol (TCP), 2,3,4,6-tetrachlorophenol (TeCP), 2,4,6-tribromophenol (TBP) and pentachlorophenol (PCP) from wine. The haloanisoles and halophenols were automatically determined using a gas chromatography-electron-capture detection (GC-ECD) system. Derivatisation of halophenols was performed at the same time as DLLME. Firstly, disperser and extraction solvents, salt addition and temperature conditions were selected. Then, the volume of disperser solvent, extraction solvent and derivatisation agent, and the percentage of base were optimised by means of a central composite design combined with desirability functions. The optimal extraction-derivatisation conditions found were 1.3 mL of acetone, 150 μL of carbon tetrachloride, 75 μL of acetic anhydride and a percentage of base of 0.7%; with no salt addition and at room temperature. Under these conditions, the proposed method showed satisfactory linearity (with correlation coefficients over 0.994), repeatability (below 9.7%) and reproducibility (below 9.9%). Moreover, detection limits were lower than the olfactory threshold of the compounds. The developed method was successfully applied to the analysis of red wine samples. To our knowledge, this is the first time that DLLME has been applied to determine cork taint responsible compounds in wine.     

Optimisation of a microwave-assisted extraction method for the simultaneous determination of haloanisoles and halophenols in cork stoppers

This study presents a method based on the use of microwave-assisted extraction (MAE) for the quantitative analysis of 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA), pentachloroanisole (PCA), 2,4,6-tribromoanisole (TBA), 2,4,6-trichlorophenol (TCP), 2,3,4,6-tetrachlorophenol (TeCP), pentachlorophenol (PCP) and 2,4,6-tribromophenol (TBP) in cork stoppers. The influential parameters of the MAE procedure (extraction time, temperature and solvent volume) were optimised using a central composite experimental design combined with desirability functions. The optimal conditions identified were temperature 170 degrees C, solvent volume 35 mL and extraction time 90 min. MAE extracts were concentrated and derivatised prior to separation and quantification by gas chromatography with electron capture detection. To evaluate the applicability of the proposed MAE method, recovery results were compared with those obtained with the Soxhlet extraction method; the results were similar with both extraction methods. The new method was also satisfactorily applied to real cork stopper samples.     

Developing an alcoholic‐assisted dispersive liquid–liquid microextraction for extraction of pentachlorophenol in water

Optimization of alcoholic‐assisted dispersive liquid–liquid microextraction of pentachlorophenol (PCP) and determination of it with high‐performance liquid chromatography (UV‐Vis detection) was investigated. A Plackett‐Burman design and a central composite design were applied to evaluate the alcoholic‐assisted dispersive liquid–liquid microextraction procedure. The effect of seven parameters on extraction efficiency was investigated. The factor studied were type and volume of extraction and dispersive solvents, amount of salt, and agitation time. According to Plackett‐Burman design results, the effective parameters were type and volume of extraction solvent and agitation time. Next, a central composite design was applied to obtain optimal condition. The optimized conditions were obtained at 170‐μL 1‐octanol and 5‐min agitation time. The enrichment factor of PCP was 242 with limits of detection of 0.04 μg L^?1. The linearity was 0.1–100 μg L^?1 and the extraction recovery was 92.7%. RSD for intra and inter day of extraction of PCP were 4.2% and 7.8%, respectively for five measurements. The developed method was successfully applied for the determination of PCP in environmental water samples.     

Trace analysis of pentachlorophenol (PCP) in wood and wood-based products – comparison of sample preparation procedures

The main problem with routine analyses of pentachlorophenol (PCP) and sodium pentachlorophenolate (Na-PCP) in wood and wood-based products is to determine critical PCP-contents. This task requires a reliable analytical method and statistical testing. An analytical procedure is described, which permits the determination of PCP and Na-PCP with sufficient sensitivity and accuracy. A medium size sieve (4 × 4 mm quadratic mesh) was found suitable for the grinding step. Different extraction techniques and solvents were tested systematically. Extraction by a combination of ultrasonication and shaking in the solvent mixture toluene/sulfuric acid showed best recoveries. The eluted PCP and Na-PCP were derivatized with acetic anhydride and determined by GC/ECD. The limits of detection and determination were 0.14 mg/kg and 0.40 mg/kg, respectively. Received: 6 August 1999 / Revised: 26 October 1999 / Accepted: 1 November 1999     

An organic solvent-free microwave-assisted extraction of some priority pollutants of phenols in lake sediments.

Alkaline water was used for the microwave-assisted extraction of some priority pollutants of phenols in sediments, i.e. phenol (Ph), 2-chlorophenol (2CP), 2,4-dichlorophenol (2,4DCP), 4-chlorophenol (4CP), 4-dinitrophenol (4NP) and pentachlorophenol (PCP). This organic solvent-free extraction procedure was optimized by studying the parameters such as pH, volume of the alkaline water, extraction pressure and time. Under the optimized conditions, the recoveries of phenols were in the range of 80% to 110%. The extracts were then cleaned-up and concentrated by microcolumn solid phase extraction (SPE) and determined by gas chromatography-flame ionization detection system. The relative standard deviation of the overall-method for most phenol determinations was about 5.0% (n = 6). The proposed method, which needs little volume (1 mL) of ethanol for SPE, has been applied to determine these phenols in sediment samples, and the analytical results are in good agreement with those achieved by Soxhlet extraction.     

Determination of pentachlorophenol in wood samples using liquid chromatography with UV absorbance, amperometric and electron-capture detection

The potential of reversed-phase liquid chromatography (RPLC) with UV and amperometric detection (AD), and of normal-phase liquid chromatography (NPLC) with UV and electron-capture detection (ECD) for the determination of pentachlorophenol (PCP) in wood samples has been studied. When PCP concentrations of at least 1-5 ppm have to be determined, RPLC-UV and RPLC-AD on C18-modified silica are useful techniques, provided a two- or three-step sample-preparation step is used. NPLC-UV on bare silica columns does not offer any advantage over RPLC-UV. NPLC-ECD on bare silica and with an acidified toluene-hexane mixture as eluent offers good selectivity and sensitivity, as well as satisfactory linearity and reproducibility for the determination of PCP in wood samples down to low ppb levels. Use of the two-step clean-up procedure is sufficient, and even a single-step procedure has been utilized. In the latter case, analysis times are longer because of the presence of late-eluting ECD-active interferences. The two-step clean-up procedure generally used involves a liquid-liquid extraction with dichloromethane, and solid-liquid sorption using a Sep Pak C18 cartridge. PCP recovery over the 0.2-10 ppm range is 75-100%. Several wood samples containing 1-50 ppm of PCP have successfully been analyzed, and the good potential of NPLC-ECD for trace-level determination of PCP has been demonstrated.     

顶空固相微萃取气相色谱法测定浓海水中的氯酚

建立浓海水中氯酚的顶空固相微萃取气相色谱法检测方法。采用顶空固相微萃取对海水淡化排放的浓海水样品中2,4,6-三氯酚(2,4,6-TCP)和五氯酚(PCP)进行分离富集,气相色谱-电子捕获检测器(μECD)测定浓海水样品中2,4,6-TCP和PCP的含量。讨论了萃取时间、萃取温度、水样盐度等实验条件对富集效率的影响,确定了萃取时间为40 min,萃取温度为60℃。2,4,6-TCP,PCP的质量浓度在0.500~20.0μg/L范围内与其色谱峰面积呈良好的线性关系,线性相关系数均大于0.999,2,4,6-TCP和PCP的检出限(2S/N)分别为0.055,0.128μg/L,测定结果的相对标准偏差为3.65%~11.4%(n=6),加标回收率为73.5%~119.0%。该方法快速,灵敏度高,适合于浓海水中氯酚的分析。     

Preparation and evaluation of a molecularly imprinted sol-gel material for on-line solid-phase extraction coupled with high performance liquid chromatography for the determination of trace pentachlorophenol in water samples

A highly selective imprinted amino-functionalized silica gel sorbent was prepared by combining a surface molecular imprinting technique with a sol-gel process for on-line solid-phase extraction-HPLC determination of trace pentachlorophenol (PCP) in water samples. The PCP-imprinted amino-functionalized silica sorbent was characterized by FT-IR, SEM, nitrogen adsorption and the static adsorption experiments. The imprinted functionalized silica gel sorbent exhibited high selectivity and offered a fast kinetics for the adsorption and desorption of PCP. The prepared sorbent was shown to be promising for on-line solid-phase extraction for HPLC determination of trace levels of PCP in environmental samples. With a sample loading flow rate of 5 ml min(-1) for 2 min, an enhancement factor of 670 and a detection limit (S/N = 3) of 6 ng l(-1) were achieved at a sample throughput of five samples h(-1). The precision (RSD) for nine replicate on-line sorbent extractions of 10 microgl(-1) PCP was 3.8%. The sorbent also offered good linearity (r = 0.9997) for on-line solid-phase extraction of trace levels of PCP. The method was applied to the determination of PCP in local lake water, river water and wastewater samples.     

Determination of pentachlorophenol and tribromophenol in sawdust by ultrasound-assisted extraction and MEKC

An ultrasonic bar-assisted extraction and CE separation procedure for the determination of pentachlorophenol (PCP) and 2,4,6-tribromophenol (TBP) residues in sawdust was developed and applied. For this purpose, micellar electrokinetic capillary chromatography (MEKC) was used and compared with a GC/MS methodology. This methodology allowed the quantification of PCP and TBP in a concentration range of 2.5-12.0 mg/kg for TBP and 2.8-12.0 mg/kg for PCP. Different sample treatment processes were evaluated in order to extract these compounds from sawdust. Better results were obtained when the residues were extracted with ultrasound-assisted hexane, filtered, evaporated, dissolved in Na(2)CO(3), and injected into the CE equipment. The optimal option for GC/MS was extraction with Na(2)CO(3 )followed by a derivation using acetic anhydride and liquid-liquid extraction with hexane. This method allowed the quantification of TBP and PCP in sawdust in a concentration range of 0.19-12.00 mg/kg and 0.14-12.00 mg/kg, respectively. The CE method was compared with the GC/MS as reference method. The results were shown to be statistically similar by both methods for PCP as well as for TBP.     

Multiple response optimisation based on desirability functions of a microwave-assisted extraction method for the simultaneous determination of chloroanisoles and chlorophenols in oak barrel sawdust

A microwave-assisted extraction (MAE) method was optimised for extracting 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA), pentachloroanisole (PCA), 2,4,6-trichlorophenol (TCP), 2,3,4,6-tetrachlorophenol (TeCP) and pentachlorophenol (PCP) from oak barrels. The method was optimised by using a central composite experimental design with extraction time, temperature and solvent volume as influential parameters. A desirability function was then employed in addition to the simultaneous optimisation of the compounds. The optimal conditions identified were temperature 130 degrees C, solvent volume 35 mL and extraction time 50 min. The compounds were determined by gas chromatography with electron-capture detection. MAE was compared with conventional Soxhlet extraction; the results obtained with MAE were in good agreement with those obtained by Soxhlet extraction.     

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.     

Optimisation of a headspace solid-phase microextraction with on-fiber derivatisation method for the direct determination of haloanisoles and halophenols in wine

A solid-phase microextraction (SPME) procedure for the determination of four haloanisoles (2,4,6-trichloroanisole, 2,3,4,6-tetrachloroanisole, pentachloroanisole and 2,4,6-tribromoanisole), as well as their precursor halophenols (2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, pentachlorophenol and 2,4,6-tribromophenol), involved in the presence of cork taint in wine, was developed. Firstly, analytes were concentrated on a SPME fiber, and then halophenols were derivatised using N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA). The compounds were desorbed for 5 min in the gas chromatography injector port and then determined with an electron capture detector. The influence of different parameters on the efficiency of extraction (volume of sample, type of fibre coating and time) and derivatisation (time, temperature and volume of MSTFA) steps was evaluated. Polyacrylate (PA) was selected as the extraction fiber, optimised parameters for SPME were 10 ml of wine, temperature 70 degrees C and extraction time 60 min. The optimal conditions identified for the derivatisation step were temperature 25 degrees C, reagent volume 50 microl and extraction time 25 min. Under optimal conditions, the proposed method showed satisfactory linearity, precision and detection limits. The method was applied successfully to the analysis of red wine samples. To our knowledge, this is the first time that headspace (HS) SPME combined with on-fiber derivatisation has been applied to determine cork taint responsible compounds in wine.     

Optimization of headspace experimental factors to determine chlorophenols in water by means of headspace solid-phase microextraction and gas chromatography coupled with mass spectrometry and parallel factor analysis

In this work an analytical procedure based on headspace solid-phase microextraction and gas chromatography coupled with mass spectrometry (HS-SPME–GC/MS) is proposed to determine chlorophenols with prior derivatization step to improve analyte volatility and therefore the decision limit (CCα). After optimization, the analytical procedure was applied to analyze river water samples. The following analytes are studied: 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TrCP), 2,3,4,6-tetrachlorophenol (2,4,6-TeCP) and pentachlorophenol (PCP). A D-optimal design is used to study the parameters affecting the HS-SPME process and the derivatization step. Four experimental factors at two levels and one factor at three levels were considered: (i) equilibrium/extraction temperature, (ii) extraction time, (iii) sample volume, (iv) agitation time and (v) equilibrium time. In addition two interactions between four of them were considered. The D-optimal design enables the reduction of the number of experiments from 48 to 18 while maintaining enough precision in the estimation of the effects. As every analysis took 1 h, the design is blocked in 2 days.     

Determination of chlorophenols in water samples using simultaneous dispersive liquid-liquid microextraction and derivatization followed by gas chromatography-electron-capture detection

Simultaneous dispersive liquid-liquid microextraction (DLLME) and derivatization combined with gas chromatography-electron-capture detection (GC-ECD) was used to determine chlorophenols (CPs) in water sample. In this derivatization/extraction method, 500 microL acetone (disperser solvent) containing 10.0 microL chlorobenzene (extraction solvent) and 50 microL acetic anhydride (derivatization reagent) was rapidly injected by syringe in 5.00 mL aqueous sample containing CPs (analytes) and K(2)CO(3) (0.5%, w/v). Within a few seconds the analytes derivatized and extracted at the same time. After centrifugation, 0.50 microL of sedimented phase containing enriched analytes was determined by GC-ECD. Some effective parameters on derivatization and extraction, such as extraction and disperser solvent type and their volume, amount of derivatization reagent, derivatization and extraction time, salt addition and amount of K(2)CO(3) were studied and optimized. Under the optimum conditions, enrichment factors and recoveries are in the range of 287-906 and 28.7-90.6%, respectively. The calibration graphs are linear in the range of 0.02-400 microg L(-1) and limit of detections (LODs) are in the range of 0.010-2.0 microg L(-1). The relative standard deviations (RSDs, for 200 microg L(-1) of MCPs, 100 microg L(-1) of DCPs, 4.00 microg L(-1) of TCPs, 2.00 microg L(-1) of TeCPs and PCP in water) with and without using internal standard are in the range of 0.6-4.7% (n=7) and 1.7-7.1% (n=7), respectively. The relative recoveries of well, tap and river water samples which have been spiked with different levels of CPs are 91.6-104.7, 80.8-117.9 and 83.3-101.3%, respectively. The obtained results show that simultaneous DLLME and derivatization combined with GC-ECD is a fast simple method for the determination of CPs in water samples.     

Microwave-assisted extraction followed by gas chromatography-mass spectrometry for the determination of endocrine disrupting chemicals in river sediments

A method for the simultaneous measurement of trace amounts of phenolic xenoestrogens, such as 2,4-dichlorophenol (2,4-DCP), 4-tert-butyl-phenol (BP), 4-tert-octylphenol (OP), 4-nonylphenol (NP), pentachlorophenol (PCP) and bisphenol A (BPA), in water samples was developed using stir bar sorptive extraction (SBSE) with in situ derivatization followed by thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS) analysis. The conditions for derivatization with acetic acid anhydride were investigated. A polydimethylsiloxane (PDMS)-coated stir bar and derivatization reagents were added to 10 ml of water sample and stirring was commenced for 10-180 min at room temperature (25 degrees C) in a headspace vial. Then, the extract was analyzed by TD-GC-MS. The optimum time for SBSE with in situ derivatization was 90 min. The detection limits of 2,4-DCP, BP, OP, NP, PCP and BPA were 2, 1, 0.5, 5, 2 and 2 pg ml(-1), respectively. The method showed good linearity over the concentration ranges of 10, 5, 2, 20, 10 and 10-1000 pg ml(-1) for 2,4-DCP, BP, OP, NP, PCP and BPA, respectively, and the correlation coefficients were higher than 0.99. The average recoveries of those compounds in river water samples were equal to or higher than 93.9% (R.S.D. <7.2%) with correction using the added surrogate standards. This simple, accurate, sensitive and selective method can be used in the determination of trace amounts of phenolic xenoestrogens in river water samples.     

Sensitivity enhancement of chlorinated phenols by continuous flow liquid membrane extraction followed by capillary electrophoresis

This paper describes a new analytical system, based on the combination of continuous flow liquid membrane extraction (CFLME) enrichment and capillary electrophoresis (CE) separation, for analysis of chlorinated phenols in water samples. Five chlorinated phenols including 3-chlorophenol (3CP), 4-chlorophenol (4CP) 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), and pentachlorophenol (PCP) were separated by CE with Tris/sodium dihydrogen phosphate solution containing methanol 1% (v/v) as the run buffer. CFLME related parameters were investigated and optimal enrichment was obtained by using 0.3 mol L(-1) Tris as acceptor and with a sample pH 5.0, a sample flow rate of 4.0 mL min(-1), and an enrichment sample volume of 150 mL. The detection limit (S/N= 3) was 6.9, 1.0, and 1.7 ng mL(-1) for DCP, PCP, and TCP, respectively. The reproducibility (RSD%, n = 6) was 5.7 for DCP, 2.5 for PCP, and 2.8% for TCP (n = 6). The proposed method was applied to the determination of chlorinated phenols in spiked water samples with relatively satisfactory recoveries.     

自制离子液体固相微萃取涂层分析人体尿液中的五氯酚

建立了顶空固相微萃取与气相色谱法（HS-SPME-GC）测定人体尿液中五氯酚（PCP）的新方法。 采用溶胶-凝胶法,加入自制的离子液体键合固相微萃取涂层,优化了萃取温度、萃取时间、pH值、离子强度及解吸时间。 结果表明,样品中加入3 g NaCl,溶液的pH值为2,并以一定速度搅拌的条件下,在80 ℃顶空萃取50 min,300 ℃下解吸5 min,方法的检测限为5.0 ng/L,线性范围为0.05～100 μg/L,相对标准偏差(RSD)为5.9%,加标回收率为106.6%。     

Dispersive liquid-liquid microextraction and liquid chromatographic determination of pentachlorophenol in water

A simple and sensitive dispersive liquid-liquid microextraction method for extraction and preconcentration of pentachlorophenol (PCP) in water samples is presented. After adjusting the sample pH to 3, extraction was performed in the presence of 1% W/V sodium chloride by injecting 1 mL acetone as disperser solvent containing 15 μL tetrachloroethylene as extraction solvent. The proposed DLLME method was followed by HPLC-DAD for determination of PCP. It has good linearity (0.994) with wide linear dynamic range (0.1–1000 μg L⁻¹) and low detection limit (0.03 μg L⁻¹), which makes it suitable for determination of PCP in water samples.