Mercury speciation and analysis in drinking water by stir bar sorptive extraction with in situ propyl derivatization and thermal desorption-gas chromatography-mass spectrometry

A method for mercury analysis and speciation in drinking water was developed, which involved stir bar sorptive extraction (SBSE) with in situ propyl derivatization and thermal desorption (TD)-GC-MS. Ten millilitre of tap water or bottled water was used. After a stir bar, pH adjustment agent and derivatization reagent were added, SBSE was performed. Then, the stir bar was subjected to TD-GC-MS. The detection limits were 0.01 ng mL(-1) (ethylmercury; EtHg), 0.02 ng mL(-1) (methylmercury; MeHg), and 0.2 ng mL(-1) (Hg(II) and diethylmercury (DiEtHg)). The method showed good linearity and correlation coefficients. The average recoveries of mercury species (n=5) in water samples spiked with 0.5, 2.0, and 6.0 ng mL(-1) mercury species were 93.1-131.1% (RSD<11.5%), 90.1-106.4% (RSD<7.8%), and 94.2-109.6% (RSD<8.8%), respectively. The method enables the precise determination of standards and can be applied to the determination of mercury species in water samples.     

Stir bar sorptive extraction coupled to thermodesorption-gas chromatography-mass spectrometry for the determination of insect repelling substances in water samples

Stir bar sorptive extraction (SBSE) in combination with thermodesorption-gas chromatography-mass spectrometry (TD-GC-MS) was applied for the determination of eight insect repellents and synergists in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 20 mL of water sample with 4 g NaCl and stirred at 1000 rpm for 180 min. Then, the stir bar was subjected to TD-GC-MS. SBSE parameters (ionic strength, presence of organic solvent and time) were optimised. Blank contamination and carryover problems were also studied. The method affords detection limits between 0.5 and 30 ng/L, except for dimethyl phthalate (DMP) (150 ng/L) due to blank contamination problems. It shows good linearity with correlation coefficients over 0.997 and reproducibility (RSD) below 20%. The extraction efficiencies were between 29% for DMP and 80% for di-n-propyl isocinchomeronate (R-326). The feasibility of the method was tested by analysing real samples such as lake water, river water and wastewater.     

Sequential stir bar sorptive extraction for uniform enrichment of trace amounts of organic pollutants in water samples

A novel extraction procedure for stir bar sorptive extraction (SBSE) termed sequential SBSE was developed. Compared to conventional SBSE, sequential SBSE provides more uniform enrichment over the entire polarity/volatility range for organic pollutants at ultra-trace levels in water. Sequential SBSE consists of a SBSE performed sequentially on a 5-mL sample first without modifier using one stir bar, then on the same sample after addition of 30% NaCl using a second stir bar. The first extraction with unmodified sample is mainly targeting solutes with high Kow (logKow>4.0), the second extraction with modified sample solution (containing 30% NaCl) is targeting solutes with low and medium Kow (logKow<4.0). After extraction the two stir bars are placed in a single glass desorption liner and are simultaneously desorbed. The desorbed compounds were analyzed by thermal desorption and gas chromatography-mass spectrometry (TD-GC-MS). Recovery of model compounds consisting of 80 pesticides (organochlorine, carbamate, organophosphorus, pyrethroid, and others) for sequential SBSE was evaluated as a function of logKow (1.70-8.35). The recovery using sequential SBSE was compared with those of conventional SBSE with or without salt addition (30% NaCl). The sequential approach provided very good recovery in the range of 82-113% for most of the solutes, and recovery less than 80% for only five solutes with low Kow (logKow<2.5), while conventional approaches (with or without salt addition) showed less than 80% recovery for 23 and 41 solutes, respectively. The method showed good linearity (r2>0.9900) and high sensitivity (limit of detection: <10ngL(-1)) for most of the model compounds even with the scan mode in the MS. The method was successfully applied to screening of pesticides at ngL(-1) level in river water samples.     

聚酰亚胺固相萃取搅拌棒的制备及其在环境水中酚类的分析应用

利用相转换法制备了聚酰亚胺吸附萃取搅拌棒,用5种有机酚作为评价标样,并与现有商品化吸附萃取搅拌棒进行比较。优化了萃取搅拌速度、溶液离子强度、萃取温度、萃取时间以及热解析温度和时间。在最佳实验条件下,100 mL 样品,30% NaCl,在25℃下,经活化5 min 后的聚酰亚胺吸附搅拌棒萃取30 min (800 r/ min),然后300℃热解析4 min,使目标物脱附,再进行色谱分析。目标物在大于两个数量级浓度范围内具有良好的线性(R≥0.9995),定量限(LOQ,S/ N=10)为0.028~0.123μg/ L,重复性为1.6%~9.7%。将SBSE 与气相色谱-质谱联用,对海水、自来水和污水中的酚类进行定性与定量分析,结果表明,聚酰亚胺吸附萃取搅拌棒具有良好的选择性,最高热解析温度350℃,在分析水中痕量极性化合物领域具有广阔应用前景。     

pH-resistant titania hybrid organic-inorganic coating for stir bar sorptive extraction of drugs of abuse in urine samples followed by high performance liquid chromatography-ultraviolet visible detection

An organic-inorganic hybrid titania-hydroxy-terminated silicone oil (titania-OH-TSO) stir bar coating was prepared by sol-gel method. The extraction performance of titania-OH-TSO coated stir bar was evaluated and compared with poly(dimethysiloxane) (PDMS), poly(dimethysiloxane)-divinylbenzene (PDMS-DVB), poly(dimethysiloxane)-β-cyclodextrin (PDMS-β-CD) and C(18) coated stir bar with five polar drugs of abuse including amphetamine (PA), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA) and ketamine (Ke) as the model analytes. The experimental results revealed that the titania-OH-TSO coated stir bar exhibited highly pH-resistant ability, good preparation reproducibility, superior selectivity and high extraction efficiency for the target compounds. Based on this fact, a new method of titania-OH-TSO coated stir bar sorptive extraction (SBSE) combined with high performance liquid chromatography (HPLC)-ultraviolet visible (UV) detection was developed for the analysis of five drugs of abuse in urine samples. The factors affecting the extraction efficiency of SBSE such as sample pH, desorption solvent, sample volume, extraction time, desorption time, stirring rate and ionic strength were investigated and the optimal extraction conditions were established. Under the optimized conditions, the limits of detection (LODs) for titania-OH-TSO coated SBSE-HPLC-UV determination of five polar drugs of abuse were in the range of 2.3-9.1 μg/L with relative standard deviations (RSDs) ranging from 7.3 to 8.9% (c=300 μg/L, n=6), and all of the target compounds exhibited good linearity over a concentration range of 30-3000 μg/L. The developed method was applied to the determination of amphetamines and Ke in urine samples of drug abusers with satisfactory results.     

整体式吸附萃取搅拌棒在检测环境水样中镉离子含量方面的应用

通过逐步聚合反应制备了一种新型整体式吸附萃取搅拌棒,将其应用于环境水中镉离子的吸附萃取.考察了介质酸度、搅拌速率、吸咐时间、解吸溶剂和时间等实验条件对吸附量的影响.控制溶液pH为6.0,搅拌棒转速为300 r/min,吸附30 min,5% HNO3作为解吸液解吸10 min,采用等离子体原子发射光谱仪对Cd离子进行检...     

应用搅拌棒吸附萃取-热脱附-气质联用技术分析人工唾液捕集吸收的卷烟主流烟气成分

采用人工唾液捕集卷烟主流烟气,应用搅拌棒吸附萃取法(SBSE)提取其中的化学成分,利用热脱附(TD)-气相色谱-质谱(GC-MS)进行分析。对脱附温度、脱附时间、冷阱温度、萃取时间及NaCl加入量等影响因素进行考察,获得优化的实验条件。在优化条件下,同一样品的6次测定所得44个组分的峰面积的相对标准偏差(RSD)平均值小于10%,说明所建方法重现性较好。应用本方法分析某品牌卷烟烟气成分的结果表明:SBSE-TD-GC-MS联用技术可用于人工唾液捕集吸收的烟气化学成分的快速分析测定。     

搅拌棒固相萃取与液相色谱联用测定水样品中烷基酚类污染物

建立了简单、快速、灵敏测定水环境中的双酚A(BPA)、辛基酚(OP)、壬基酚(NP)的方法。以聚(N-乙烯基咪唑-二乙烯基苯)整体材料为涂层的搅拌棒固相萃取技术富集目标物,然后与高效液相色谱-二极管阵列检测器联用测定水样品中烷基酚类污染物。考察了萃取时间、解析时间、样品基质的pH值、离子强度等实验条件对萃取效率的影响。在最佳条件下,3种目标化合物的线性范围是1.0～200μg/L,检出限LOD(S/N=3)在0.13～0.66μg/L之间,定量限LOQ(S/N=10)在0.44～2.19μg/L之间。在对海水和污水处理厂的实际水样测定中,3种目标化合物的不同加标水平的回收率为37.8%～101.1%。本方法具有简便、快速、高效、灵敏等优点。     

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.     

Analysis of 51 persistent organic pollutants in soil by means of ultrasonic solvent extraction and stir bar sorptive extraction GC-MS

A novel method based on ultrasonic solvent extraction and stir bar sorptive extraction (SBSE) for the analysis of 51 persistent organic pollutants including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenylethers (PBDEs) in soil samples was developed. The different parameters that affect both the extraction of analytes from the soil samples, such as solvent selection, solvent volume, mass of soil, and extraction time, and the partitioning from the solvent/water mixture to the PDMS were studied. The final selected conditions consisted of the extraction of 1 g of soil with 15 mL methanol by sonication for 30 min. The methanol extract was mixed with 85 mL of Milli-Q water and extracted by means of SBSE for 14 h at 900 rpm. The stir bars were analyzed by thermal desorption-GC-mass spectometry (TD-GC-MS). The effects of the matrix on the recovery of the various pollutants under the developed method were studied using two soils with very different physicochemical properties. Method sensitivity, linearity, repeatability, and reproducibility were also studied. Validation and accuracy of the method were conducted by analyzing two commercial certified reference materials (CRMs). The main advantage of this method resides in the fact that a small amount of a nontoxic solvent (methanol) is needed for the extraction of only 1 g of solid sample allowing LODs ranging from 0.01 to 2.0 microg/kg. Repeatability and reproducibility variations were lower than 20% for all investigated compounds. Results of the CRMs verify the high accuracy of this method.     

Stir bar sorptive extraction and thermal desorption-gas chromatography-mass spectrometry for trace analysis of triclosan in water sample

A simple and highly sensitive method called stir bar sorptive extraction (SBSE) and thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS), which is used for the determination of trace amounts of 5-chloro-2-(2,4-dichlorophenoxy)phenol (triclosan) in river water samples, is described. A stir bar coated with polydimethylsiloxane (PDMS) is added to a 10mL water sample and stirring is carried out for 120min at room temperature (25 degrees C) in a vial. Then, the PDMS stir bar is subjected to TD-GC-MS. The detection limit of triclosan is 5ngL(-1) (ppt). The method shows linearity over the calibration range (0.02-20mugL(-1)) and the correlation coefficient is higher than 0.997 for triclosan standard solution. The recovery of triclosan in river water samples ranges from 91.9 to 108.3% (RSD: 4.0-7.0%). This simple, accurate, sensitive, and selective analytical method may be used in the determination of trace amounts of triclosan in river water samples.     

Determination of parabens in house dust by pressurised hot water extraction followed by stir bar sorptive extraction and thermal desorption-gas chromatography-mass spectrometry

This study describes the development of a new method for determining p-hydroxybenzoic esters (parabens) in house dust. This optimised method was based on the pressurised hot water extraction (PHWE) of house dust, followed by the acetylation of the extracted parabens, stir bar sorptive extraction (SBSE) with a polydimethylsiloxane stir bar, and finally analysis using thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). The combination of SBSE and PHWE allows the analytes to be preconcentrated and extracted from the aqueous extract in a single step with minimal manipulation of the sample. Furthermore the in situ acetylation of parabens prior to SBSE improved their extraction efficiency and their GC-MS signal. The method showed recoveries of between 40 and 80%, good linearity, repeatability and reproducibility (<10% RSD, at 100 ng g(-1), n=5), low limits of detection (from 1.0 ng g(-1) for propyl paraben to 2.1 ng g(-1) for methyl paraben) and quantification (from 3.3 ng g(-1) for propyl paraben to 8.5 ng g(-1) for methyl paraben). The proposed method was applied to the analysis of house dust samples. All the target parabens were found in the samples. Methyl and propyl parabens were the most abundant, with concentrations up to 2440 ng g(-1) and 910 ng g(-1), respectively. The high levels of parabens found in the samples confirm the importance of determining organic contaminants in indoor environments.     

Sensitive determination of strongly polar aromatic amines in water samples by stir bar sorptive extraction based on poly(vinylimidazole-divinylbenzene) monolithic material and liquid chromatographic analysis

A simple and sensitive method for the determination of polar aromatic amines (PAAs) was developed using stir bar sorptive extraction (SBSE) coupling to high-performance liquid chromatography. A hydrophilic poly(vinylimidazole-divinylbenzene) (VIDB) monolithic material was prepared and acted as SBSE coating. The influences of polymerization conditions for VIDB on the extraction efficiency were investigated using aniline and 2,4-dinitroaniline as detected solutes. To achieve optimum extraction performance for PAAs, several parameters including extraction and desorption time, desorption solvent, ionic strength and pH value of sample matrix were investigated. The results showed that under the optimized experimental conditions, the method showed good sensitivity and excellent recoveries, as well as advantages such as linearity, simplicity, low cost and high feasibility. The extraction performance of present method to the target compounds also compared with commercial SBSE which using polydimethylsiloxane as coating and other SBSE which based on monolithic materials. Finally, the proposed method was successfully applied to the determination of PAAs in lake and sea waters, and excellent recoveries of spiked target compounds in real samples were obtained.     

Stir bar sorptive extraction for the analysis of short‐chain chlorinated paraffins in water

An optimised method using stir bar sorptive extraction (SBSE) and a thermal desorption‐GC‐electron capture detector (GC‐ECD) for the determination of short‐chain chlorinated paraffins from water samples was developed. Recoveries near to 100% were obtained by using 20 mm×0.5 mm (length×film thickness) PDMS commercial stir bars from 200 mL spiked water samples and 20% methanol addition with an extraction period of 24 h. Method sensitivity, linearity and precision were evaluated for surface water and wastewater spiked samples. A LOD of 0.03 and 0.04 μg/L was calculated for surface and wastewater, respectively. The precision of the method given as an RSD was below 20% for both matrices. The developed method was applied for the analysis of two real samples from a contaminated river and a wastewater treatment plant. Results were in accordance with those obtained using a previously developed method based on solid phase microextraction (SPME).     

Simultaneous determination of 64 pesticides in river water by stir bar sorptive extraction and thermal desorption-gas chromatography-mass spectrometry

A method for determining 68 pesticides in river water using stir bar sorptive extraction (SBSE)-thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS) is described. SBSE sampling was optimized for sample solution pH, salting-out and methanol addition. Although salting-out enhanced the ability of the method to extract most of the pesticides with low absolute recoveries, the absolute recoveries of four pesticides were not improved by salting-out. The detection limits of the method for the pesticides ranged from 0.2 to 20 ng/l. Analyte recoveries from a river water sample spiked with standards at 10 and 100 ng/l were 58.5–132.0% (RSD: 1.8–15.8%) and 61.0–121.3% (RSD: 1.4–20.2%), respectively.     

大体积搅拌棒吸附萃取技术与热脱附-气相色谱-质谱法测定地表水中多环芳烃

基于搅拌棒吸附萃取(SBSE)技术建立了气相色谱-质谱测定地表水中16种多环芳烃(PAHs)的分析方法。该法采用多搅拌吸附棒同时富集,依次热脱附冷聚焦后进样的方式有效解决了搅拌棒吸附时间长、富集水样体积小等问题。优化后的结果表明,在0.2~10 ng/L范围内(萘为0.5~10 ng/L范围),16种PAHs的线性关系良好,相关系数(r)均0.99,方法检出限(MDL)为0.03~0.20 ng/L(萘为0.50 ng/L)。用该方法对钱塘江流域地表水进行测定,共检测出11种PAHs,含量为0.13~1.57 ng/L,不同添加水平下的加标回收率为75.6%~108.9%。该法可应用于地表水样品中该类物质的超痕量检测。     

Determination of steroid sex hormones in wastewater by stir bar sorptive extraction based on poly(vinylpyridine-ethylene dimethacrylate) monolithic material and liquid chromatographic analysis

In this study, a simple and rapid method was developed for the determination of seven steroid hormones in wastewater. Sample preparation and analysis were performed by stir bar sorptive extraction (SBSE) based on poly(vinylpyridine-ethylene dimethacrylate) monolithic material (SBSEM) combined with high-performance liquid chromatography with diode array detection. To achieve the optimum extraction performance, several main parameters, including extraction and desorption time, pH value and contents of inorganic salt in the sample matrix, were investigated. Under the optimized experimental conditions, the method showed good linearity and repeatability, as well as advantages such as sensitivity, simplicity, low cost and high feasibility. The extraction performance of SBSEM to the target compounds also compared with commercial SBSE which used polydimethylsiloxane as coating. Finally, the proposed method was successfully applied to the determination of the target compounds in wastewater samples. The recoveries of spiked target compounds in real samples ranged from 48.2% to 110%.     

Simple and sensitive monitoring of sulfonamide veterinary residues in milk by stir bar sorptive extraction based on monolithic material and high performance liquid chromatography analysis

A simple, rapid, and sensitive method for the quantitative monitoring of five sulfonamide antibacterial residues (SAs) in milk was developed by stir bar sorptive extraction (SBSE) coupling to high performance liquid chromatography with diode array detection. The analytes were concentrated by SBSE based on poly (vinylimidazole–divinylbenzene) monolithic material as coating. The extraction procedure was very simple, milk was diluted with water then directly sorptive extraction without elimination of fats and protein in samples was required. To achieve optimum extraction performance for SAs, several parameters, including extraction and desorption time, desorption solvent, ionic strength and pH value of sample matrix were investigated. Under the optimized experimental conditions, low detection limits (S/N = 3) quantification limits (S/N = 10) of the proposed method for the target compounds were achieved within the range of 1.30–7.90 ng/mL and 4.29–26.3 ng/mL from spiked milk, respectively. Good linearities were obtained for SAs with the correlation coefficients (R²) above 0.996. Finally, the proposed method was successfully applied to the determination of SAs compounds in different milk samples and satisfied recoveries of spiked target compounds in real samples were obtained.     

Direct enrichment of phenols in lake and sea water by stir bar sorptive extraction based on poly (vinylpyridine-ethylene dimethacrylate) monolithic material and liquid chromatographic analysis

A poly (vinylpyridine-ethylene dimethacrylate) monolithic material was synthesized and selected as stir bar sorptive extraction (SBSE) medium. The influences of polymerization conditions on the extraction efficiency were investigated using phenol and p-nitrophenol as target analytes. Based on this, six strongly polar phenols in water were directly concentrated by the new SBSE and determined with high performance liquid chromatography equipped with diode array detector. To achieve the optimum extraction performance, several main parameters, including extraction and desorption time, pH value and contents of inorganic salt in the sample matrix were investigated. The method showed good linearity and acceptable recoveries, as well as advantages such as sensitivity, simplicity, low cost and high feasibility. The proposed method was successfully applied to the determination of phenolic compounds in lake and sea waters.     

Determination of steroid sex hormones in urine matrix by stir bar sorptive extraction based on monolithic material and liquid chromatography with diode array detection

A simple, rapid and sensitive method for simultaneous determination of six steroid sex hormones in urine matrix was developed by the combination of stir bar sorptive extraction (SBSE) with high performance liquid chromatography (HPLC) and diode array detection (DAD). A poly (methacrylic acid stearyl ester-ethylene dimethacrylate) was synthesized and selected as SBSE extraction medium. To achieve the optimum extraction performance, several parameters, including agitation speed, desorption solvent, extraction and desorption time, pH value, inorganic salt and organic solvent content of the sample matrix were investigated. Under the optimized experimental conditions, low detection limits (S/N=3) and quantification limits (S/N=10) of the proposed method for the target compounds were achieved within the range of 0.062-0.38 and 0.20-1.20 ng/mL, respectively from spiked urine, respectively. The calibration curves of six steroid sex hormones showed good linearity ranging from 1.0 to 200 ng/mL with linear coefficient R2 values above 0.990. Good method reproducibilities presented as intra- and inter-day precisions were also found with the R.S.D.s less than 9.2 and 10.0%, respectively. Finally, the proposed method was successfully applied to the determination of the target compounds in a urine sample from a pregnant woman.