Vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction

A novel sample pre-treatment technique, based on vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction (VSLLME), followed by gas chromatography-flame photometric detection (GC-FPD) has been developed for the determination of seven organophosphorus pesticides (OPPs) in wine and honey samples. In the VSLLME method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Meanwhile, the addition of a surfactant, which was used as an emulsifier, could enhance the speed of the mass-transfer from aqueous samples to the extraction solvent. The main parameters relevant to this method were investigated and the optimum conditions were established: 15 μL chlorobenzene was used as extraction solvent, 0.2 mmol L(-1) Triton X-114 was selected as the surfactant, the extraction time was fixed at 30s, 3% sodium chloride was added and the extraction process was performed under the room temperature. Under the optimum conditions, limits of detections (LODs) were varied between 0.01 and 0.05 μg L(-1). The relative standard deviation (RSD, n=6) ranged from 2.3% and 8.9%. The linearity was obtained by five points in the concentration range of 0.1-50.0 μg L(-1). Correlation coefficients (r) varied from 0.9969 to 0.9991. The enrichment factors (EFs) were in a range of 282-309. Finally, the proposed method has been successfully applied to the determination of target analytes in real samples. The recoveries of the target analytes in wine and honey samples were between 81.2% and 108.0%.     

离子色谱-串联质谱法检测酒类产品中10种有机酸

建立了一种离子色谱-串联质谱(IC-MS/MS)测定白酒、黄酒、干红葡萄酒3种酒类样品中10种有机酸含量的方法。白酒样品氮吹后,经去离子水稀释,用IC-MS/MS分析检测;干红葡萄酒样品和黄酒样品,对比不同固相萃取小柱净化能力,最终选择石墨化炭黑固相萃取小柱进行净化,经去离子水稀释,用IC-MS/MS分析检测。选用高容量、强亲水性的Dionex IonPac^TM AS11-HC型阴离子分析柱进行分离,以淋洗液自动发生器在线产生的KOH水溶液为淋洗液,进行梯度淋洗。淋洗液经抑制器抑制后直接进入电喷雾电离串联质谱(ESI-MS/MS),采用负离子模式电离,多反应监测(MRM)模式检测,外标法定量。在该实验条件下:草酸、富马酸、马来酸、苹果酸、酒石酸、柠檬酸、奎尼酸和乌头酸在0.05~2 mg/L范围内线性关系良好;琥珀酸在0.05~5 mg/L范围内线性关系良好;乳酸在0.05~10 mg/L范围内线性关系良好(相关系数r²>0.99)。10种有机酸的检出限(S/N=3)在1.0~8.0 μg/L范围内,定量限(S/N=10)在3.5~26.5 μg/L范围内,在3个不同浓度的添加水平下,平均回收率在83.0%~112.1%之间,相对标准偏差≤9.1%,满足检测要求。该方法前处理简单,不使用有机溶剂,不需进行衍生化处理,测定快速、准确,灵敏度高,适用于3种酒类样品中10种有机酸的定量分析,为酒类食品的风味及品质测定提供方法支持。     

Sorptive extraction with in-sample acetylation for gas chromatography-mass spectrometry determination of ethylphenol species in wine samples

An inexpensive and effective sample preparation procedure for the determination of three ethylphenolic off-flavours (4-ethylphenol, 4-ethylguaiacol and 4-ethylcathecol) in wine samples is presented. Analytes were in situ acetylated and concentrated using a disposable silicone sorbent (DSS) exposed to the diluted sample. After that, the analytes were recovered with ethyl acetate and determined by gas chromatography with mass spectrometry. The influence of different parameters (volume of acetic anhydride, basic catalyst, ionic strength, sorbent format, sampling mode and extraction time) on the efficiency of derivatization and extraction steps is discussed. Under optimized conditions, 2 mL of wine were diluted with 15 mL of an aqueous solution of potassium bicarbonate (5%, m/v) in a 22 mL vessel, containing 2 g of sodium chloride. The volume of acetic anhydride and the extraction time were set at 90 μL and 2 h, and the extraction was carried out at room temperature (20±2°C). Analytes were concentrated using a silicone disc (5 mm diameter × 0.5 mm thickness) and further desorbed with 0.2 mL of ethyl acetate. The achieved limits of quantification (LOQs), defined as the concentration of each compound providing a signal 10 times higher than the baseline noise, stayed between 5 and 15 ng mL(-1). The method provided a linear response range of up to 5000 ng mL(-1) and relative recoveries from 91% to 116%. The 4-ethylphenol off-flavour was detected in most red wine samples at concentrations of up to 2700 ng mL(-1).     

液相色谱-离子阱-飞行时间串联质谱同时检测葡萄酒中14种杂环胺

建立了液相色谱-离子阱-飞行时间串联质谱法(LC-IT-TOF MS)同时测定葡萄酒中14种杂环胺(HAAs)残留量的分析方法。样品于乙酸乙酯碱性条件下提取,内标法定量,Phenomenex Kinetex C18 100A色谱柱(100 mm×2.1 mm, 2.6 μm)分离,以乙腈和30 mmol/L甲酸铵为流动相进行梯度洗脱。实验结果表明,2-氨基-3,7,8-三甲基咪唑［4,5-f］喹喔啉在1～500 μg/L、2-氨基-3,8-二甲基咪唑［4,5-f］喹喔啉在10～500 μg/L、其他12种杂环胺在5～500 μg/L质量浓度范围内线性良好,相关系数均不小于0.9945,检出限(以信噪比为3计) 0.33～1.77 μg/L。14种杂环胺在加标水平为10、50、100 μg/L时的回收率分别为71.6%～96.4%、72.9%～101.9%、74.5%～103.3%,相对标准偏差(RSD, n=6)分别为2.9%～7.9%、1.7%～5.3%、1.8%～4.8%。结果显示该方法线性范围宽,精密度和准确度较高,分析时间短,净化效果好,可满足葡萄酒中多种杂环胺残留同时检测的要求。     

Determination of pesticide residues in wine by membrane-assisted solvent extraction and high-performance liquid chromatography–tandem mass spectrometry

The determination of pesticides in food products is an essential issue to guarantee food safety and minimise health risks of consumers. A protocol based on membrane-assisted solvent extraction and liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) that allows the determination of 18 pesticides in red wine at minimum labour effort for sample preparation was developed and validated. Ten millilitres of wine were extracted using 100 μL of toluene filled in a non-porous polyethylene membrane bag which is immersed in the wine sample. After 150 min extraction under stirring, an aliquot of the extraction solution is analysed using HPLC-MS/MS. The limits of quantification ranged from 3 ng/L for Pirimicarb to 1.33 μg/L for Imidacloprid. Quantification by matrix-matched calibration provided relative standard deviations ≤16 % for most of the target pesticides. The linearity of calibration was given over three to four orders of magnitude, which enables the reliable measurement of a broad range of pesticide concentrations, and for each target pesticide, the sensitivity of the protocol meets the maximum residue levels set by legislations at least for wine grapes. Good agreement of results was found when the new method was compared with a standard liquid-liquid extraction protocol. In five wine samples analysed, Carbendazim and Metalaxyl were determined at micrograms per litre concentrations, even in some of the organic wines. Tebuconazol and Cyprodinitril were determined at lower abundance and concentration, followed by Spiroxamin and Diuron.     

Optimization of extraction procedure and chromatographic separation of glyphosate, glufosinate and aminomethylphosphonic acid in soil

Analysing herbicides in soil is a complex issue that needs validation and optimization of existing methods. An extraction and analysis method was developed to assess concentrations of glyphosate, glufosinate and aminomethylphophonic acid (AMPA) in field soil samples. After testing extractions by accelerated solvent extraction and ultrasonic extraction, agitation was selected with the best recoveries. Water was preferred as solvent extraction because it resulted in a cleaner chromatogram with fewer impurities than was the case with alkaline solvents. Analysis was performed by FMOC pre-column derivatization followed by high-performance liquid chromatography (HPLC) on a 300 mm C(18) column which permitted enhanced separation and sensitivity than a 250 mm C(18) column and increased resistance than the NH(2) column for soil samples. This extraction and analysis method allowing a minimum of steps before the injection in the HPLC with fluorescence detection is efficient and sensitive for a clay-loamy soil with detection limits of 103 μg kg(-1) for glyphosate, 15 μg kg(-1) for glufosinate and 16 μg kg(-1) for AMPA in soil samples.     

Hydrazone-based ligands for micro-solid phase extraction-high performance liquid chromatographic determination of biogenic amines in orange juice

Eight hydrazone-based ligands were synthesized, trapped in a silica sol-gel matrix, and were subsequently used in the micro-solid phase extraction (μ-SPE) of biogenic amines (BAs). The BAs investigated were tryptamine, phenylethylamine, putrescine, histamine, tyramine and spermidine. Prior to the extraction, dansyl chloride was added to the samples which were heated to 70°C for 10 min. The samples were extracted with μ-SPE, after which analytes were desorbed using acetonitrile via ultrasonication. The extracts were analysed by high performance liquid chromatography (HPLC) with ultraviolet detection. Of the eight ligands investigated as sorbents, benzophenone 2,4-dinitrophenylhydrazone was found to be the most promising. The enhanced π-π interaction between the analytes and the ligand facilitated the adsorption process. Under the most suitable extraction conditions, the method demonstrated good linearity with correlation coefficient of more than 0.985 over a concentration range of 1-50 μg L(-1). Satisfactory repeatability with relative standard deviations of 7.43-11.30% (n=3) were obtained. Detection limits ranged from 3.8 to 31.3 ng L(-1). The μ-SPE method exhibited lower recoveries (71.5-87.4%) when compared to the solid phase extraction technique (79.7-95.0%), but enrichment factors of 94-460 were obtained. The proposed μ-SPE-HPLC method was applied to the determination of BAs in orange juice purchased from local supermarkets, with satisfactory results. The orange juices were characterized by the presence of relatively high levels of putrescine (range, 550-2210 μg L(-1)) but tryptamine and phenylethylamine were not detected in any of the tested samples.     

Analysis of benzene, toluene, ethylbenzene, xylenes and n-aldehydes in melted snow water via solid-phase dynamic extraction combined with gas chromatography/mass spectrometry

The present study describes a method based on headspace-solid-phase dynamic extraction (HS-SPDE) followed by GC/MS for the qualitative and quantitative analysis of benzene, toluene, ethylbenzene, o-, m- and p-xylene (BTEX), and n-aldehydes (C(6)-C(10)) in water. To enhance the extraction capability of the HS-SPDE a new cooling device was tested that controls the temperature of the SPDE needle during extraction. Extraction and desorption parameters such as the number of extraction cycles, extraction temperature, desorption volume and desorption flow rate have been optimized. Detection limits for BTEX ranged from 19 ng/L (benzene) to 30 ng/L (m/p-xylene), while those for n-aldehydes ranged from 21 ng/L (n-heptanal) to 63 ng/L (n-hexanal). At a concentration level of 2 microg/L, the relative standard deviations (RSDs) for BTEX ranged from 3.9% (benzene) to 15.3% (ethylbenzene), while RSDs for n-aldehydes were between 6.1% (n-octanal) and 16.5% (n-hexanal) (n=7). Best results were obtained when the analyzed water samples were heated to 50 degrees C. At a water temperature of 70 degrees C GC responses decreased for all analyzed compounds. At a defined water temperature, a significant improvement of the GC response was achieved by cooling of the SPDE fiber during water extraction in comparison to an extraction keeping the fiber at room temperature. Evaluating the extraction cycles, for BTEX, the sensitivity was almost similar using 20, 40 and 60 extraction cycles. In contrast, the highest GC responses for n-aldehydes were achieved by the use of 60 extraction cycles. Optimizing the desorption parameters, best results were achieved using the smallest technical available desorption volume of 500 microL and the highest technical desorption flow rate of 50 microL/s. The method was applied to the analysis of melted snow samples taken from the Jungfraujoch, Switzerland (3580 m asl), revealing the presence of BTEX and aldehydes in snow.     

悬浮固化-分散液液微萃取-液相色谱-串联质谱测定纺织废水中磷系阻燃剂

建立了悬浮固化-分散液液微萃取结合液相色谱-串联质谱测定纺织废水中5种痕量磷系阻燃剂的方法。通过对萃取过程中萃取剂、分散剂的种类与体积、盐浓度、溶液pH值等对萃取效率的影响因素优化,确立了最佳萃取条件。采用了密度小于水的十一烷醇（400 μL）为萃取剂,甲醇（300 μL）为分散剂,控制溶液pH值在6~9之间,NaCl添加量为2 g,萃取时间为涡旋2 min。在优化的萃取条件下,该方法在2~100 μg/L均有良好的线性关系,相关系数大于0.995,除二（2,3-二溴丙基）磷酸酯（BIS）的检出限为5 μg/L外,三（2-氯乙基）磷酸酯（TCEP）、三（1,3-二氯-异丙基）磷酸酯（TDCP）、三（1-氮丙啶基）氧化膦（TEPA）和三（2,3-二溴丙基）磷酸酯（TRIS）的检出限均为2 μg/L。后整理、染色和印花等实际废水样品加标试验表明,方法的平均回收率为71.6%~114.5%,RSD为2.7%~11.2%（n=6）。对11个样品进行检测,其中3个废水样品检出TCEP与TDCP化合物,含量为2.6~3.4 μg/L。本方法简单,快速,灵敏度好且环保绿色,能够对纺织废水中的5种痕量磷系阻燃剂进行准确的定性与定量检测。     

分子印迹固相萃取-气相色谱-质谱法测定猪尿中4种β-受体激动剂

建立了分子印迹固相萃取结合气相色谱-质谱测定猪尿中β-受体激动剂氯丙那林、马步特罗、克伦特罗、莱克多巴胺的方法.应用分子印迹柱富集并净化猪尿液中4种β-受体激动剂,比较了分子印迹固相萃取与常规固相萃取的净化效果.通过BSTFA-1％ TMS硅烷化衍生,氘代克伦特罗和氘代莱克多巴胺为校正内标,气相色谱-质谱测定.在优化条...     

Electrokinetic injection across supported liquid membranes: New sample pretreatment technique for online coupling to capillary electrophoresis. Direct analysis of perchlorate in biological samples

A simple and sensitive method for quantifying perchlorate in biological samples using CE and capacitively coupled contactless conductivity detection was developed. An online combination of a supported liquid membrane, an inert polypropylene membrane impregnated with 1-hexanol, and electrokinetic injection of perchlorate across the supported liquid membrane directly into the separation capillary reduced the need for laborious sample pretreatment procedures, resulting in a cheap and rapid method with low LODs capability. Baseline separation of perchlorate and other anions in biological samples was achieved in background electrolyte solution consisting of 15 mM nicotinic acid and 1 mM 3-(N,N-dimethylmyristylammonio)propanesulfonate at pH 3.3. The analytical method showed excellent parameters in terms of reproducibility; RSD values for peak areas and corrected migration times at a spiked concentration of 100 μg/L of perchlorate were below 10 and 0.4%, respectively. Linear calibration curves were obtained for perchlorate in the concentration range 10-1000 μg/L (r(2) >0.999) with LODs between 2 and 5 μg/L for human urine, breast milk, serum, cow's milk, and red wine. Recoveries at 25 μg/L of perchlorate were between 97 and 106% for all biological samples. The low LODs rivaling those of presently used analytical methods support the use of this method for quantification of perchlorate in biological samples in the future.     

Determination of 1-hydroxypyrene in human urine by HPLC with electrochemical detection at a boron-doped diamond film electrode

A high-performance liquid chromatographic method with electrochemical detection (HPLC-ED) at a boron-doped diamond film electrode with preliminary separation and preconcentration by solid-phase extraction (SPE) has been developed for the determination of 1-hydroxypyrene (1-HP) in human urine. 1-HP is among the most widely used biomarkers of exposure to polycyclic aromatic hydrocarbons. Optimal HPLC-ED conditions have been found: mobile phase methanol-0.05 mol L(-1) phosphate buffer pH 5.0 (80:20, v/v), detection potential +1,000 mV versus Ag/AgCl (3 mol L(-1) KCl), and flow rate 0.8 mL min(-1). For SPE, LiChrolut(?) RP-18 E cartridges were used. The extraction yield was (87.0 ± 5.8)% (n = 5). The concentration dependence of 1-HP was measured in the concentration range from 0.01 to 10 μmol L(-1) (2.18-2,180 μg L(-1)) using methanolic solutions resulting from the SPE pretreatment of spiked human urine samples. The limit of detection (signal-to-noise ratio 3) and the limit of quantification (signal-to-noise ratio 10) of the biomarker were 0.013 μmol L(-1) (2.84 μg L(-1)) and 0.043 μmol L(-1) (9.39 μg L(-1)), respectively, which is sufficient for its determination in the urine of persons exposed to polycyclic aromatic hydrocarbons.     

磁固相萃取-高效液相色谱联用测定尿样中的1-羟基芘

采用磁固相萃取-高效液相色谱-荧光检测方法(MSPE-HPLC-FD)分析了尿样中芘代谢物1-羟基芘(1-Hydroxyperene 1-OHP).2mL尿样以0.1 mol/L醋酸钠溶液(pH 4.5)稀释至4 mL,酶水解后,再以0.1 mol/L醋酸钠溶液(pH 5.0)稀释至10mL,采用十八烷基膦酸改性的磁性介孔纳米粒子(50 mg)为萃取介质,对其进行MSPE富集,涡旋萃取1 min,甲醇解吸3min.解吸液经氮气吹干重新定容后,进行液相色谱分析.本方法在0.01～ 1.00 μg/L范围内线性良好(R2=0.9996);检出限为0.001μg/L日内相对标准偏差小于9.7％(n=5),日间相对标准偏差小于12.9％.将本方法应用于多个人体尿液样品中1-OHP含量的检测,结果满意.为确保结果的科学性和可靠性,测定结果用尿肌酐含量进行了归一化.     

Role of different salts on cloud-point extraction of isoprocarb and promecarb insecticides followed by high-performance liquid chromatography

The influence of salt additive on cloud point extraction (CPE) of isoprocarb and promecarb insecticides is described. Types of salt (Na(2)CO(3), CaCl(2), MgSO(4), Na(2)SO(4), NaHCO(3) and NaCl) and concentrations were studied. The extracted target compounds were analyzed using reversed phase high-performance liquid chromatography. Among the salts studied, Na(2)CO(3) was found to be the most effective salt for salting out of both insecticides, resulting in high extraction efficiency (>95%) and high enrichment factor of up to 18 compared to extraction without preconcentration. The optimum CPE conditions were 1.5% (w/v) Triton X-114, 3.0% (w/v) Na(2)CO(3), and 20-min equilibration at 45°C. Under the selected conditions, the linear range of 0.05 to 3.0 mg/L was found for both analytes. The limits of detection for isoprocarb and promecarb were 10 and 20 μg/L, respectively. High intra-day (n = 9) and inter-day (n = 3 × 4 days) precisions with relative standard deviations <1% and <8% were obtained for retention time and peak area, respectively. The proposed method was successfully applied for the residue analysis of target compounds in beverages (i.e., fruit juice, vegetable juice and wine samples), which provided high recoveries (>80%, on average) for spiked samples at three levels (0.05, 0.10 and 0.50 mg/L).     

Comparison of the performance of conventional, temperature-controlled, and ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction combined with high-performance liquid chromatography in analyzing pyrethroid pesticides in honey samples

This research paper presents a comparative study of the performance of conventional, ultrasound-assisted (UA), and temperature-controlled (TC) ionic liquid (IL) dispersive liquid-phase microextraction (IL-DLLME). Various parameters that affect extraction efficiency, such as type and volume of extraction and disperser solvent, centrifugation time, salt addition, effect of temperature on TC-IL-DLLME, and effect of sonication time on UA-IL-DLLME, were evaluated. UA-IL-DLLME was found to provide the best extraction efficiency. Under optimized conditions, great enrichment factors (506-515) and good recoveries (101.2-103.0%) were obtained by analyte extraction in real samples. The limit of detections (LODs) ranged from 0.21 to 0.38 μg L(-1). Good linearity was obtained in the range of 0.5-200 μg L(-1) for ethofenprox and tetramethrin, and 1-200 μg L(-1) for meperfluthrin and alpha-cypermethrin. Based on optimized conditions, the UA-IL-DLLME method was applied and combined with high-performance liquid chromatography with diode array detection (HPLC-DAD) to determine the presence of ethofenprox, tetramethrin, meperfluthrin, and alpha-cypermethrin in honey samples.     

A new strategy to simultaneous microextraction of acidic and basic compounds

The simultaneous extraction of acidic and basic pollutants from water samples is an interesting and debatable work in sample preparation techniques. A novel and efficient method named ion pair based surfactant assisted microextraction (IP-SAME) was applied for extraction and preconcentration of five selected acidic and basic aromatic species as model compounds in water samples, followed by high performance liquid chromatography-ultraviolet detection. A mixture including 1 mL of ultra-pure water (containing ionic surfactant as emulsifier agent) and 60 μL 1-octanol (as extraction solvent) was rapidly injected using a syringe into a 10.0 mL water sample which formed an emulsified solution. IP-SAME mechanism can be interpreted by two types of molecular mass transfer into the organic solvent (partitioning and ion pairing for non-ionized and ionized compounds, respectively) during emulsification process. The effective parameters on the extraction efficiency such as the extraction solvent type and its volume, type of the surfactant and its concentration, sample pH and ionic strength of the sample were optimized. Under the optimum conditions (60 μL of 1-octanol; 1.5 mmol L(-1) cethyltrimethyl ammonium bromide (CTAB) as emulsifier agent and sample pH 10.0), the preconcentration factors (PFs), detection limits and linear dynamic ranges (LDRs) were obtained in the range of 87-348, 0.07-0.6 μg L(-1) and 0.1-200 μg L(-1) respectively. All of natural water samples were successfully analyzed by the proposed method.     

Development of a screening method for the determination of PCBs in water using QuEChERS extraction and gas chromatography-triple quadrupole mass spectrometry

A new method has been developed and validated for the simultaneous analysis of 11 polychlorinated biphenyls (PCBs), in water samples at trace levels by gas chromatography coupled to triple quadrupole mass spectrometry (GC-QqQ-MS/MS). Water samples were extracted by the QuEChERS (Quick Easy Cheap Effective Rugged and Safe) method. The QqQ analyzer acquired data in multiple reactions monitoring (MRM), permitting both quantification and confirmation in a single injection with a running time reduced up to 11.0 min. The effect of matrix interferences in extracts on analyte quantification and the identification of PCBs in water samples was deeply studied. The results showed that PCBs were prone to strong matrix interactions in water samples, and the quantification and identification of PCBs were highly affected by a matrix enhancement effect. To evaluate the performance of the method, validation experiments were carried out on water samples at three spiking levels (1.6, 8.0, 40.0 μg L(-1)). Recovery was in the range of 95 - 109% at 1.6 μg L(-1), 90 - 95% at 8.0 μg L(-1) and 97 - 102% at 40.0 μg L(-1), respectively. Precision values expressed as relative standard deviation (RSD) were lower than 15%. Linearity in the range of 0.5 - 50.0 μg L(-1) provided determination coefficients (R(2)) higher than 0.999 for all compounds. The limits of detection (LODs) for PCBs were ≤0.1 μg L(-1) and the limits of quantification (LOQs) ranged from 0.04 to 0.3 μg L(-1). The applicability of the proposed method to detect and quantify PCBs has been demonstrated in analyse of 15 real samples.     

高效液相色谱-串联质谱法同时测定水体和沉积物中12种有机磷酸酯类化合物

建立了高效液相色谱-质谱联用技术结合固相萃取和液液萃取方法检测水体和沉积物中12种磷酸酯类(OPEs)化合物残留的方法.水样样品经HLB固相萃取柱富集,乙酸乙酯洗脱两次,沉积物样品以乙腈超声萃取,旋转蒸发至干,用超纯水稀释后重复水样处理步骤,采用ZORBAX Eclipse Plus C18色谱柱(150 mm×2.1 mm, 3.5 μm)进行分离,以0.2%甲酸-甲醇作为流动相进行梯度洗脱,采用正离子MRM监测模式,外标法定量分析.水样中,12种OPEs在0.05、0.10和0.50 μg/L加标水平下,除TMP (28.5%~47.8%)和TEHP (22.4%~73.8%) 外,其余目标化合物的平均回收率为66.4%~115.0%,相对标准偏差为0.5%~9.1%,方法定量限(MOQ)为0.001~0.050 μg/L;沉积物中,在5、10和50 μg/kg加标水平下,除TMP(35.7%~44.9%)、TCEP (31.2%~48.9%)外,其余目标化合物的平均回收率为65.9%~120.0%,相对标准偏差为0.01%~9.5%,方法定量限(MOQ)为0.02~2.0 μg/kg(dw).基于上述方法对太湖水样和沉积物样品中目标化合物定量检测分析,∑OPEs含量分别为0.1~1.7 μg/L和8.1~420 μg/kg dw.     

Simultaneous determination of trace level riot control agents in environmental water by solid-phase microextraction and gas chromatography coupled with a flame ionization detector

In this paper, a direct immersion solid-phase microextraction procedure for the simultaneous analyses of four primary riot control agents: 2-chloroacetophenone, o-chlorobenzylidene malonitrile, dibenz(b,f)-1,4-oxazepine, and oleoresin capsicum at μg/L concentration from environmental water was developed. Several parameters that influence the extraction effectiveness were investigated, including fiber type, extraction temperature, extraction time, starring rate, and salinity. Under the recommended conditions, the optimized method had reasonable linearity and accuracy. The average recovery of this method ranged from 84 to 108.1%. The limit of detection for all the analytes ranged from 0.2 to 3 μg/L and the limit of quantification ranged from 1 to 10 μg/L, respectively. A relative standard deviation from 3.0 to 4.3% can be achieved depending on the compounds. The procedure was applied to analyze all the four riot control agents simultaneously in several environmental samples.     

Application of ionic-liquid supported cloud point extraction for the determination of microcystin-leucine-arginine in natural waters

A cloud point extraction method has been developed using an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMiM PF(6)) for the determination of a widely studied cyanotoxin (microcystin leucine-arginine, MCLR) in natural waters. Extraction parameters such as sample pH, extraction temperature, extraction time, the amount of ionic liquid and the amount of extraction volume were investigated and optimized to achieve the maximum extraction efficiency. The results obtained indicated a good linearity with the correlation coefficient of 0.995 over the range of 0.5-50 μg L(-1). The relative standard deviation (RSD) of the method was 7.5% (n=6). The calculated method detection limit was 0.03 μg L(-1) (n=6). The practical applicability of the technique was demonstrated by analyzing water samples (n=9) collected from three different sites in local reservoirs.