Influence of solvent and soil type on the pressurised fluid extraction of PAHs

Pressurised fluid extraction (PFE) of polycyclic aromatic hydrocarbons (PAHs) from a certified reference material (CRM) 524 has been firstly optimised following a central composite design. The instrumental parameters of the PFE (pressure, temperature, extraction time and number of solvent cycles) were studied in order to obtain maximum extraction yields. Neither pressure nor extraction time or temperature seemed to have any significant effect on the extraction yield, therefore one extraction cycle was enough to exhaustively extract all the PAHs from CRM 524. Once the instrumental conditions were established, the extraction yields obtained with eight different solvents or solvent mixtures [acetone, dichloromethane, acetonitrile, acetone-dichloromethane (1 + 1 v/v), acetone-isohexane (1 + 1 v/v), isohexane, methanol and toluene] from the CRM 524 were compared and showed that the best recoveries were obtained with acetone-isohexane (1 + 1 v/v). Finally, the effect of sand, silt, clay and the organic matter content of soil was investigated with respect to recovery of PAHs by PFE with different solvents or solvent mixtures for aged soil samples. In this case, eight soils with different sand, silt, clay and organic matter contents were slurry spiked with PAHs and aged for 19 days. Three aliquots of each slurry spiked soil were extracted with the previously mentioned solvents and the results were studied by means of principal component analysis (PCA) of the whole data set (soil composition, solubility parameter of the solvent and recoveries of all PAHs) and partial least squares (PLS). Clay and organic matter content and the squared solubility parameter have the highest correlation with the recovery of PAHs from soil samples.     

快速溶剂萃取—气相色谱法分析土壤中的20种有机氯

采用加速溶剂萃取—气相色谱法对土壤中20种有机氯农药进行了提取测定.通过改变加速溶剂萃取条件,选取了最佳条件参数,减少了组份的损失;通过改变气相色谱条件,使得20种有机氯农药快速分离.该方法具有操作简便、灵敏度高、检出限低、快速、溶剂消耗少等优点,方法检出限为1.23～ 3.11 μg/kg,实际样品的加标回收率为62.3％～119.7％.     

Comparison of pressurized fluid extraction, Soxhlet extraction and sonication for the determination of polycyclic aromatic hydrocarbons in urban air and diesel exhaust particulate matter

In order to characterize and compare the chemical composition of diesel particulate matter and ambient air samples collected on filters, different extraction procedures were tested and their extraction efficiencies and recoveries determined. This study is an evaluation of extraction methods using the standard 16 EPA PAHs with HPLC fluorescence analysis. Including LC analysis also GC and MS methods for the determination of PAHs can be used. Soxhlet extraction was compared with ultrasonic agitation and pressurized fluid extraction (PFE) using three solvents to extract PAHs from diesel exhaust and urban air particulates. The selected PAH compounds of soluble organic fractions were analyzed by HPLC with a multiple wavelength shift fluorescence detector. The EPA standard mixture of 16 PAH compounds was used as a standard to identify and quantify diesel exhaust-derived PAHs. The most effective extraction method of those tested was pressurized fluid extraction using dichloromethane as a solvent.     

云南曲靖某煤化工基地及周边土壤中多环芳烃的检测研究

采用快速溶剂提取处理土壤样品,利用气相色谱质谱内标法测定土壤中多环芳烃,其检出限范围为2.01~3.68μg/kg,相对标准偏差为2.6%~14.7%,加标回收率为67.1%~119%。结果表明,此方法具有良好的灵敏度、准确度和精密度。本研究对11个不同采样点土壤进行了检测分析,并考察了土壤中多环芳烃的污染水平。     

气相色谱/质谱法测定水中15种酞酸酯类化合物

采用固相萃取-气相色谱/质谱法测定水中15种酞酸酯类化合物,确定方法的最优条件为:依次用10 m L正己烷和丙酮混合溶剂(V/V=5∶1)、甲醇和空白试剂水活化C18固相萃取柱后,水样以5 m L/min过柱萃取,再以8 m L正己烷:丙酮(V/V=5∶1)混合溶剂洗脱后,浓缩至1 m L,进气相色谱/质谱测定。该法的检出限为0.18~0.38μg/L,在0.50~20.0 mg/L范围内线性良好,相关系数均0.996。空白水样的加标回收率为71.8%~120%,相对标准偏差为1.73%~12.7%;实际废水水样的加标回收率为64.8%~135%,相对标准偏差为2.75%~18.0%。     

Development and application of microwave assisted extraction (MAE) for the extraction of five polycyclic aromatic hydrocarbons in sediment samples in Johannesburg area, South Africa

A microwave-assisted extraction (MAE) method was verified and applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) in sediment samples. Soxhlet extraction was used as the reference method. The optimum MAE was carried out with 20 mL of hexane/acetone (1:1, v/v) mixture in a 1-g sample at 250 W for 20 min. Soxhlet extraction was carried out with 250 mL of dichloromethane:hexane (1:1, v/v) mixture in a 15-g sample for 24 h in a water bath maintained at 60 °C. The collected extracts were both cleaned up, reduced to 1 mL under nitrogen and then injected into an HPLC fluorescence. To increase the sample throughput, simultaneous MAE was performed. The obtained percentage recoveries ranged from 61 to 93 and 88–98 for MAE and SE, respectively. The optimised MAE method was validated using certified reference material. It was then applied to real sediment samples from in and around the greater Johannesburg area. The sediments from Jukskei River were found to be the most polluted while Hartbeespoort Dam sediments were found to be least polluted. The overall order of concentrations for the studied PAHs per site was as follows: Jukskei River?>?Kempton Park?>?Centurion Dams?>?Natalspruit River (PIT)?>?Hartbeespoort Dam.     

Simultaneous derivatization and extraction of nitrophenols in soil and rain samples using modified hollow-fiber liquid-phase microextraction followed by gas chromatography–mass spectrometry

A simple and sensitive method based on a modified hollow-fiber liquid-phase microextraction followed by gas chromatography–mass spectrometry has been successfully developed for the extraction and simultaneous derivatization of some nitrophenols (NPs) in soil and rain samples. Microwave-assisted solvent extraction was used for the extraction of NPs from the soil, while the rain sample was directly applied to the previously mentioned method. Briefly, in this method, the analytes were extracted from aqueous samples into a thin layer of organic solvent (dodecane?+?10 % tri-n-octylphosphine oxide) sustained in the pores of a porous hollow fiber. Then, they were back-extracted using a small volume of organic acceptor solution (25 μl; 10 mg/L N-methyl-N-(trimethylsilyl)trifluoroacetamide, as derivatization reagent, in acetonitrile) that was located inside the lumen of the hollow fiber. Under the optimized extraction conditions, enrichment factors of 255 to 280 and limits of detection of 0.1 to 0.2 μg/L (S/N?=?3) with dynamic linear ranges of 1–100 μg/L were obtained for the analytes. The accuracy of the approach was tested by the relative recovery experiments on spiked samples, with results ranging from 93 to 113 %. The method was shown to be rapid, cost-effective, and potentially interesting for screening purposes.     

On-line solid phase extraction and liquid chromatography/tandem mass spectrometry to quantify pharmaceuticals, pesticides and some metabolites in wastewaters, drinking, and surface waters

A simple on-line method was developed for the analysis of pharmaceuticals, pesticides and some metabolites in drinking, surface and wastewater samples. The technique is based on the use of on-line solid-phase extraction combined with liquid chromatography electrospray tandem mass spectrometry with positive electrospray ionization (LC-ESI(PI)-MS/MS). The injection of only 1 mL of filtered water sample is used with a total analysis time of 20 min, including the period required to flush the SPE cartridge with organic solvent and reconditioning the LC column. Method detection limits were in the range of 2 to 24 ng L(-1) for the compounds of interest, with recoveries from 87 to 110% in surface as well as wastewater samples. Matrix effects were observed for some compounds without exceeding more than 25%. All results displayed a good degree of reproducibility, with relative standard deviations (RSD) of less than 12% for all compounds. Moreover, at least 200 samples were analyzed without altering the performance of the pre-concentration column. This method was preferred over traditional off-line procedures because it minimizes tedious sample preparation, increases productivity and sample throughput. The analysis of various water and wastewater samples showed that caffeine, carbamazepine and atrazine could be detected in all the samples analysed and the selected compounds are always present in at least one of the sample types.     

建设用地土壤中11种半挥发性有机物的测定

利用快速溶剂萃取-气相色谱-质谱法对建设用地土壤中11种半挥发性有机物(SVOC S)进行分析,并优化了萃取溶剂、温度和循环次数。经测定,标准曲线的相关系数(R 2)>0.990,相对标准偏差(RSD)为1.7%~14%,加标回收率为65.0%~86.4%,方法检出限为0.01~0.06 mg/kg。结果表明,方法的精密度、准确度、灵敏度均能满足建设用地土壤中11种SVOC S的分析要求。     

磁性分散固相萃取-气相色谱法测定水中氯苯类化合物

采用磁性分散固相萃取技术富集水中氯苯类化合物，用气相色谱法测定，并对萃取剂的用量、萃取时间、解吸溶剂、氯化钠加入量等条件进行优化。试验表明，方法在0．001 mg/L～2．50 mg/L 范围内，氯苯类化合物各组分线性良好，方法检出限在0．600μg/L～5．00μg/L范围内。地表水实际水样的加标回收率为83．1％～93．4％，RSD为4．8％～7．3％。     

Quantification of pendimethalin in soil and garlic samples by microwave-assisted solvent extraction and HPLC method

A method for the residual pendimethalin in soil and vegetable samples was developed. The method is based on extraction of pendimethalin from samples using microwave-assisted solvent extraction (MASE) with acetone, ethanol, and water as extraction solvent. Extracted pendimethalin samples were analyzed by high-performance liquid chromatography with ultraviolet detector at 240 nm. The MASE parameters, temperature, heating time, and solvent types were optimized with the feasibility of MASE application in the determination of pendimethalin extraction efficiency of pendimethalin from soil and vegetable samples. The maximum temperature that can be used during the heating for MASE is 60°C, where the recovery percentages reached 97%. Linearity for pendimethalin was found in the range of 2?C20 ??g mL^???1 with limits of detection and limits of quantification of 0.059 and 0.17 ??g mL^???1, respectively.     

水样中痕量十溴联苯醚的分散液-液微萃取条件的优化

采用正交设计和Box-Penhnken响应面设计,对分散液-液微萃取技术萃取水样中痕量十溴联苯醚的条件进行了筛选和优化,得到最佳条件:四氯乙烯为萃取剂(10μl)、丙酮作分散剂(1ml)、pH范围5~9、离子强度,2%NaCl及萃取时间10min。此优化条件下分散液-液微萃取技术的萃取回收率可达92.37%~104.38%,富集倍数为508~611。优化条件下方法的线性范围为0.01~100ng/ml,检出限(S/N=2)为3.0pg/ml,加标回收率为96.25%~102.16%,精密度为5.44%~6.34%。     

Single drop microextraction and gas chromatography–mass spectrometry for the determination of diflufenican, mepanipyrim, fipronil, and pretilachlor in water samples

An analytical method for the determination of diflufenican, mepanipyrim, pretilachlor, and fipronil in water samples was developed using single drop microextraction in the direct immersion mode and gas chromatography–mass spectrometry. A factorial fractionated design of type 2^6–1 at two levels was performed, to study the influence of experimental variables such as ionic strength, pH, agitation speed, extraction time, drop volume, and sample volume. To establish the optimal conditions for the variables that were significant, a Doehlert design was performed. The optimum conditions of extraction were 1 μL of heptane immersed in 4.0 mL of sample with continuous agitation at 500 rpm for 30 min at room temperature. The developed method proved to have good linearity for the range studied. The detection limits were 0.07 μg L^?1 for diflufenican, 0.03 μg L^?1 for mepanipyrim, 0.08 μg L^?1 for pretilachlor, and 1.39 μg L^?1 for fipronil. The method was validated on river water samples, showing the absence of matrix effect and recoveries ranged from 90.1 to 107.8 %. The results show that the method developed is accurate, sensitive, rapid, simple, and low cost, so it is recommended for application in the analysis of these different classes of pesticides in water samples.     

Optimization of extractants, purifying packings, and eluents for analytical extraction of organochlorine pesticides in Hydragric Acrisols

In this study, we screened for an economic, rapid, and efficient hypotoxic pretreatment method for organochlorine pesticides in soil samples for gas chromatography (GC) analysis. The analytical extraction efficiencies of 11 different extractants, nine types of solid-phase purification (SPP) cartridge packings, and three types of eluents for 13 organochlorine pesticides (OCPs) in spiked and natural Chinese red soil (Hydragric Acrisols) were evaluated using an ultrasonic extraction and solid-phase purification method. High percent recoveries (85-106%) were obtained for the 13 organochlorine pesticides in soil when petroleum ether/acetone/water (10:5:2, v/v) was used an extractant. They were purified using celite SPP cartridge packing and eluted with 9 mL of dichloromethane/petroleum ether (1:9, v/v). The OCPs purification pretreatment of Hydragric Acrisols, using the above method, meets the GC analysis requirements. Compared with other traditional pretreatment methods for OCPs in soil samples, this method has several advantages, such as a short extraction time, reducing the amount of solvent, having no emulsion phenomenon, and hypotoxicity to the laboratory technicians. The concentrations of 1,1,1,-trichloro-2(p-chlorophenyl)-2-(o-chlorophenyl) ethane (DDTs; 3.42-8.08 ng g(-1)) in field soils were higher than the hexachlorocyclohexane concentration (2.94-6.12 ng g(-1)). The 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (p,p'-DDE)?+?1,1-dichloro-2,2-bis(p-chlorophenyl)-ethane (p,p'-DDD)/p,p'-DDT ratio in this field soil was approximately 2.7, suggesting that no new DDT pollution source was introduced into the sampling site.     

土壤中酞酸酯类化合物监测方法的质量控制研究

从监测结果控制的角度对近10年的土壤中PAEs监测方法进行了探讨,重点比较了索氏萃取柱净化GC/MS、微波萃取柱净化GC、加速溶剂萃取柱净化GC/MS和加速溶剂萃取GPCGC/MS方法的检出限、精密度和准确度。旨在为中国土壤监测方法的建立提供基础支撑,为开展质量控制工作提供评价依据。     

Determination of 16 polycyclic aromatic hydrocarbons in water using fluorinated polyaniline-based solid-phase microextraction coupled with gas chromatography

The study on the performance of a fluorinated polyaniline (PANI) as a fiber coating for solid-phase microextraction (SPME) had been reported and 16 polycyclic aromatic hydrocarbons (PAHs) were selected to evaluate the performance of this fiber. Various parameters including sample volume, extraction temperature, time of desorption and extraction, pH and ionic strength were investigated intensively. A direct comparison between PANI-SPME fiber and commercial fiber was conducted. The results showed that the PANI-SPME coating had high affinity towards target compounds and the proposed method was successfully applied for the detection of real samples: rainfall and Taihu Lake water collected from Southern China. The whole PANI-SPME-GC method offers acceptable accuracy, precision and sensitivity and low detection limits, which is applicable to monitor trace levels of PAHs in real water bodies.     

The determination of carbonyl compounds in air using a robotic sampling preparation system integrated to a gas chromatograph with a nitrogen-phosphorus detector

A totally automated solid phase extraction gas chromatography procedure was developed for the sampling and analysis of carbonyl compounds in air. In this system, two PrepStation modules were used, one for the preparation and elution of 2,4-dinitrophenylhydrazine silica cartridges, and the other for air sampling. The sample collected by the sampling module was eluted to an autosampler vial in the PrepStation module and then transferred to the gas chromatograph for analysis via a robotic arm. The sampling module was modified to enable air sampling via an external pump. A typical run by this technique required 142 min, 100 min for air sampling and 42 min for the other operations, including a GC analysis time of 25 min. Recoveries of at least 85% were obtained for all compounds studied. The detection limits for formaldehyde, acetaldehyde and acetone were 2.2, 2.7 and 2.2 ppbv, respectively. All operations, including the conditioning of the cartridges, were performed without any intervention from the analyst.     

气相色谱-质谱法测定废酸油渣中的16种多环芳烃

建立了废酸油渣中16种多环芳烃超声萃取、Florisil萃取柱净化、气相色谱-质谱测定的方法。笔者对提取方式、提取剂类型和体积、提取时间和次数、净化方式等进行研究,采用无水硫酸钠分散,二氯甲烷作为提取剂超声40 min,提取液经纯水清洗、离心后取适量有机相经过3 g Florisil萃取柱净化,采用气相色谱-质谱选择离子模式(SIM),加入内标进行定量分析。结果表明:二氯甲烷提取效率比正己烷好,丙酮可能引起酸性样品中多环芳烃的降解,丙酮超声萃取时加入无水硫酸钠能在一定程度上防止目标物降解,但萃取效率不可控制,宜采用二氯甲烷作为萃取剂。分散提取能有效减少提取时间,超声清洗仪超声40 min提取效率为86.2%～104%。3g Florisil萃取柱净化比1 g Florisil萃取柱净化和GPC净化效果略好。方法检出限为0.4～1.3 mg/kg,6次空白加标的相对标准偏差为2.3%～15.3%,6个实际样品测定结果的相对标准偏差为1.2%～27.3%,基体加标回收率为51.3%～126%,连续校准稳定。该方法适用于废酸油渣样品中16种多环芳烃的检测,比直接溶解有效,比加速溶剂萃取、索氏提取、微波萃取和超声探头萃取简单、快捷,能有效减少设备污染和腐蚀,净化方法有效,测定结果准确可靠,是实现大批量样品检测的可行方法。     

三重四极杆质谱技术测定固体废弃物中多氯联苯

以二氯甲烷为萃取剂,采用快速溶剂萃取、凝胶渗透色谱净化、三重四极杆质谱技术测定固体废弃物中7种多氯联苯单体,选择十氯联苯为内标物,2,4,5,6-四氯间二甲苯为替代物。质谱采用MRM扫描,优化了目标物质保留时间、母离子和子离子质量数及碰撞能量等参数。方法在0.050 mg/L～2.00 mg/L范围内线性良好,7种多氯联苯单体的检出限为0.194 ng/g～0.355 ng/g(以称取30 g样品、定容至2.0 mL计),标准样品回收率多在60%～105%之间,空白加标样品测定值的相对标准偏差在8.6%～13.0%之间。     

微波提取高效液相色谱法测定土壤中15种痕量多环芳烃

采用微波提取结合高效液相色谱技术测定了土壤中15种PAHs的含量.比较了用微波提取、索氏提取和超声萃取3种土壤样品的前处理方法对多环芳烃测定的影响,考察了色谱柱的性能、梯度洗脱条件的优化、荧光检潮波长程序变换及柱温等因素对15种PAHs组分之同分离的影响.经优化后的HPLC方法对15种PAHs的最低检测限为0.10～0.80 μg/kg,相对标准偏差为0.60%～4.60%,方法的回收率为58.1%～97.8%.实验结果表明,该方法兵有高效、快速、灵敏等特点,可以用于环境土壤样品中痕量PAHs的检测.