加速溶剂萃取气相色谱-质谱法检测土壤中双酚A

建立加速溶剂萃取后利用气相色谱-质谱法测定土壤中双酚A的检测方法。样品前处理采用加速溶剂萃取,经硅胶柱净化,以HP-5MS色谱柱,采用气相色谱-质谱联用全扫描和选择离子扫描进行分析。结果表明:双酚A在0.1~10.0 mg/L的质量浓度范围内,线性良好,相关系数为0.999 3;方法检出限为0.01 mg/kg(S/N=3)。在0.1,1.0,10 mg/kg这3个加标水平下,样品的平均回收率为82.5%~101.7%,相对标准偏差(RSD)≤3.3%。该方法简便快速,灵敏度及准确度高,可用于土壤中双酚A的分析测定。     

Recycling of solvent used in a solvent extraction of petroleum hydrocarbons contaminated soil

The application of water washing technology for recycling an organic composite solvent consisting of hexane and pentane (4:1; TU-A solvent) was investigated for extracting total petroleum hydrocarbons (TPH) from contaminated soil. The effects of water volume, water temperature, washing time and initial concentration of solvent were evaluated using orthogonal experiments followed by single factor experiments. Our results showed that the water volume was a statistically significant factor influencing greatly the water washing efficiency. Although less important, the other three factors have all increased the efficacy of water washing treatment. Based on a treatment of 20 g of contaminated soil with a TPH concentration of 140 mg g(-1), optimal conditions were found to be at 40°C, 100 mL water, 5 min washing time and 660 mg g(-1) solvent. Semi-continuous water extraction method showed that the concentration of the composite solvent TU-A was reduced below 15 mg g(-1) d.w. soil with a recovery extraction efficiency >97%. This finding suggests that water washing is a promising technology for recycling solvent used in TPH extraction from contaminated soils.     

土壤标准样品中有机氯农药的加速溶剂萃取/净化方法优化

通过优化土壤标准样品中有机氯农药的加速溶剂萃取/净化方法的最佳条件。结果表明:采用正己烷-二氯甲烷混合溶剂(1∶1,ν/ν)为提取剂,萃取温度100℃,压力为2 000 psi,循环1次萃取15 min,经弗罗里硅土固相萃取柱净化,气相色谱/质谱法进行检测,空白加标回收率为72%~122%,相对标准偏差介于1.0%~2.3%之间;基体加标回收率为64%~140%,相对标准偏差介于1.8%~3.2%之间;方法检出限为0.58~44.2μg/kg,定量限为1.94~147μg/kg,相比于索氏提取法,该方法简单、快捷、经济,已用于实际土壤样品中有机氯农药的检测。     

Comparison of fat retainers in accelerated solvent extraction for the selective extraction of PCBs from fat-containing samples

Five types of fat retainers were investigated for the lipid-free extraction of PCBs from fat-containing matrixes using accelerated solvent extraction: florisil, basic alumina, neutral alumina, acidic alumina, and sulfuric acid-impregnated silica. All of the fat retainers generated fat-free extracts when the fat/fat retainer ratio was 1:40. Sulfuric acid-impregnated silica and florisil were the only retainers that gave completely clear extracts, and the former was the only not to show any reaction when treated with sulfuric acid after the extraction. Using sulfuric acid-impregnated silica as fat retainer, on-line cleanup of fat-containing matrixes was possible, as demonstrated for naturally contaminated fish meal as well as certified cod liver oil (CRM 349).     

Determination of fluoroquinolone antibacterial agents in sewage sludge and sludge-treated soil using accelerated solvent extraction followed by solid-phase extraction

A method for the quantitative determination of humanuse fluoroquinolone antibacterial agents (FQs) ciprofloxacin and norfloxacin in sewage sludge and sludge-treated soil samples was developed. The accelerated solvent extraction was optimized with regard to solvents and operational parameters, such as temperature, pressure, and extraction time. A 50 mM aqueous phosphoric acid/ acetonitrile mixture (1:1) was found to be optimum in combination with an extraction temperature of 100 degrees C at 100 bar, during 60 and 90 min for sewage sludge and sludge-treated soil samples, respectively. A cleanup step using solid-phase extraction substantially improved the selectivity of the method. Overall recovery rates for FQs ranged from 82 to 94% for sewage sludge and from 75 to 92% for sludge-treated soil, with relative standard deviations between 8 and 11%. Limits of quantification were 0.45 and 0.18 mg/kg of dry matter for sewage sludge and sludge-treated soils, respectively. The presented method was successfully applied to untreated and anaerobically digested sewage sludges and sludge-treated soils. Ciprofloxacin and norfloxacin were determined in sewage sludges from several wastewater treatment plants with concentrations ranging from 1.40 to 2.42 mg/kg of dry matter. Therefore, contrary to what may be expected for human-use pharmaceuticals, FQs may reach the terrestrial environment as indicated by the occurrence of FQs in topsoil samples from experimental fields, to which sewage sludge had been applied.     

Determination of chlorophenols in soils using accelerated solvent extraction combined with solid-phase microextraction

A method for the determination of chlorophenols in soil samples using accelerated solvent extraction (ASE) with water as the solvent combined with solid-phase microextraction (SPME) and GC/MS has been developed. Important ASE parameters, such as extraction temperature and time, were optimized using a spiked wetland soil. The effect of small amounts of organic modifiers on the extraction yields was studied. An extraction temperature of 125 degrees C and 10 min extractions performed three times proved optimal. Two ASE-SPME procedures without and with an organic modifier (5% acetonitrile) were evaluated with respect to precision and detection limits (LOD). The reproducibility of replicate water extractions/SPME determinations (n = 6) was in the range 7-20% relative standard deviation for the nine chlorophenols investigated. LOD values in the low-ppb range were achieved for all chlorophenols. The ASE-SPME procedure presented here was applied to the determination of chlorophenols in soil samples taken from contaminated areas near Bitterfeld, Germany.     

Factors affecting high-pressure solvent extraction (accelerated solvent extraction) of additives from polymers

Irganox 1010 (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)] propionate) is successfully extracted from polypropylene using solvents at high temperatures and pressures in a homemade accelerated solvent extraction system. For example, using freeze-ground polymer, 90% extraction is possible within 5 min with 2-propanol at 150 °C. Extraction curves for 2-propanol and acetone fit well to the "hot ball" model, previously developed for supercritical fluid extraction. Diffusion coefficients are determined for extractions with 2-propanol, acetone, and cyclohexane over a range of temperatures, and the activation energies for the diffusion are 134, 107, and 61 kJ mol(-)(1), respectively. The lower figure for acetone and cyclohexane indicates that these solvents swell the polymer more than does 2-propanol. The polymer dissolves in the solvent at too high a temperature, which causes blockage of the transfer lines. For maximum extraction rates, the highest temperature for each solvent that avoids dissolution of the polymer should be used. The use of mixed solvents is investigated and shows advantages in some cases, with the aim of producing a solvent that will swell the polymer but not dissolve it.     

Evaluation of accelerated solvent extraction for butyltin speciation in PACS-2 CRM using double-spike isotope dilution-GC/ICPMS

Pressurized liquid extraction using the accelerated solvent extractor (Dionex ASE 200) has been evaluated for the determination of mono-, di- and tributyltin (MBT, DBT, and TBT, respectively) in PACS-2 certified reference material. A double-enriched spike containing 119Sn-enriched MBT and TBT and 118Sn-enriched DBT allowed for the simultaneous determination of the three butyltin species and the factors governing species interconversion. The stability of the spike was evaluated by reverse isotope dilution experiments covering more than one year with satisfactory results. Quantitative recoveries using ASE for TBT and DBT were obtained at temperatures above 110 degrees C. The effect of the extraction time and number of static cycles was evaluated. Results suggest that extraction efficiency was quantitative with extraction times as low as 10 min for all butyltin species at 110 degrees C. Decomposition reactions were only detected at the higher temperatures assayed (140 and 175 degrees C) and that was only for the degradation of DBT to MBT (approximately 4%). The results found for MBT were approximately 25% higher than the certified value for the PACS-2 sediment reference material in agreement with previous results obtained by ultrasonic and microwave assisted extraction.     

Optimization of accelerated solvent extraction for polyhalogenated dibenzo-p-dioxins and benzo-p-furans in mineral and environmental matrixes using experimental designs

This paper deals with the optimization of accelerated solvent extraction (ASE) for the analysis of the polychlorinated dibenzo-p-dioxins, benzo-p-furans (PCDD/Fs), mixed bromine/chlorine-dibenzo-p-dioxins, and benzo-p-furans (so-called MXDD/Fs) in solid samples. Previous theoretical studies have shown that these compounds exhibit similar electronic properties. It is reasonable to assume that there is little difference in the behavior, formation, and toxicity of PCDD/Fs and MXDD/Fs. Indeed, for most of the cases, the affinity is defined by these weak interactions. Only eight native standards are available for the MXDD/Fs; hence, the use of similar compounds (native and (13)C(12)-labeled), such as PCDD/Fs, is required to optimize and to validate experimental methods. This would allow conclusions to be applied for the MXDD/Fs without extended studies involving complex synthesis methods. Experimental design methodology was used to evaluate the influence of five parameters (temperature, pressure, static time, number of cycles, and solvent nature) on the polyhalogenated dibenzodioxin and -furan (PXDD/Fs) extractions in different materials. The extraction profiles and the optimal operating conditions were determined for each matrix from the modeling of extraction performance. The two following effects, the relative peak area and the co-extracted matrix (CEM), were screened in this study. The temperature of extraction was found to be the most important parameter. ASE offers automation and appears to be as efficient as Soxhlet or Soxtet; however, a major benefit was that a 4-fold decrease in extraction time was obtained. Results suggest that extraction efficiency was quantitative with extraction times as low as 15 min for all congeners at 130 degrees C with a mixed solvent (n-hexane/acetone (1/1)). Under these operating conditions, the CEM and the degradation of the highly brominated compounds were minimized. The analysis of some real life samples from municipal solid waste incinerators showed significant amounts of PXDD/Fs.     

Washing enhanced electrokinetic remediation for removal cadmium from real contaminated soil

The main objective of this study is to evaluate the combination of electrokinetic remediation and soil washing technology in order to remove cadmium from contaminated soil. This paper presents the results of an experimental research undertaken to evaluate different washing and purging solutions to enhance the removal of cadmium from a real contaminated soil during electrokinetic remediation. Two different experimental modules were applied in the laboratory. Soil was saturated with tap water, while acetic and hydrochloric acids, as well as ethylenediaminetetraacetic acid (EDTA) were used as purging solutions in the first module. Results show that there was a decrease of cadmium concentration near anode, but a significant increase in the middle of the cell, due to the increasing pH. Citric, nitric and acetic acids were used for soil washing and purging solutions in the second module. In this case, an 85% reduction of cadmium concentration was achieved. Therefore, results indicate that soil pH and washing solutions are the most important factors in governing the dissolution and/or desorption of Cd in a soil system under electrical fields.     

Use of solvent extraction to remediate soils contaminated with hydrocarbons

The main objective of this research is to exploit the possibility of using an ex situ solvent extraction technique for the remediation of soils contaminated with semi-volatile petroleum hydrocarbons. The composition of the organic phase was chosen in order to form a single phase mixture with an aqueous phase and simultaneously not being disturbed (forming stable emulsions) by the soil particles hauling the contaminants. It should also permit a regeneration of the organic solvent phase. As first, we studied the miscibility domain of the chosen ternary systems constituted by ethyl acetate-acetone-water. This system proved to satisfy the previous requirements allowing for the formation of a single liquid phase mixture within a large spectrum of compositions, and also allowing for an intimate contact with the soil. Contaminants in the diesel range within different functional groups were selected: xylene, naphthalene and hexadecane. The analytical control was done by gas chromatography with FID detector. The kinetics of the extractions proved to be fast, leading to equilibrium after 10 min. The effect of the solid-liquid ratio on the extraction efficiency was studied. Lower S/L ratios (1:8, w/v) proved to be more efficient, reaching recoveries in the order of 95%. The option of extraction in multiple contacts did not improve the recovery in relation to a single contact. The solvent can be regenerated by distillation with a loss around 10%. The contaminants are not evaporated and they remain in the non-volatile phase. The global results show that the ex situ solvent extraction is technically a feasible option for the remediation of semi-volatile aromatic, polyaromatic and linear hydrocarbons.     

Polychlorinated biphenyl (PCB) recovery from spiked organic matrix using accelerated solvent extraction (ASE) and Soxhlet extraction

The recovery of five PCB congeners from PCB spiked organic matrices was studied using Accelerated solvent extraction (ASE) and Soxhlet extraction (SE). The chromatogram of ASE extract was found to be relatively clean and similar to that of SE extract. ASE extraction efficiency was dependent on the operation temperature and sample size loading. ASE showed extraction efficiency comparable or slightly higher to that of SE for the PCB spiked organic matrix. PCB recovery from spiked matrix was dependent on the type and molecular weight of congener, and nature of matrix. For some selected PCB congeners, ortho-substitution did influence the PCB recovery from graphite matrix.     

Supercritical fluid extraction and accelerated solvent extraction of dioxins from high- and low-carbon fly ash

This study investigates the replacement of Soxhlet extraction by supercritical fluid extraction (SFE) or accelerated solvent extraction (ASE) for the removal of dioxins from municipal waste incinerator fly ash. SFE is very matrix dependent; higher percent recoveries versus Soxhlet extraction can be obtained for low-carbon-level fly ash, but only a few percent of dioxins can be extracted from high-carbon-level fly ash. The addition of large quantities of toluene in the extraction cell prior to extraction of high-carbon fly ash improves the recovery of the lowest chlorinated dioxins (approximately 90%), but a maximum of 20% of the octachlorodibenzo-p-dioxins can be extracted. Since large quantities of toluene are needed to improve the recoveries, ASE with toluene was tested. Recoveries similar to Soxhlet extraction can be obtained in 2 h at 80 degrees C. Increasing the temperature to 150 degrees C increases the extraction rate and yields recoveries of approximately 110-160% compared to 48-h Soxhlet extraction for all congeners for both low- and high-carbon fly ashes. These results question the choice of Soxhlet extraction as a reference method for dioxin determination.     

Supercritical fluid extraction/gamma-radiolysis of PCBs from contaminated soil.

Off-line supercritical fluid extraction (SFE) followed by gamma-radiolysis as an alternative treatment technique for PCB-contaminated soil was investigated in this study using BZ #54 (2, 2',6,6'-tetrachlorobiphenyl) as the model compound. The preliminary results indicate that removal of BZ #54 from spiked sand and soil using SFE at 150 degrees C and 20 MPa is 98% and 93%, respectively. The reduction efficiency of 864 mg/l BZ #54 in isooctane by gamma-radiolysis is 99.8% at an absorbed dose of 500 kGy.     

微乳液在溶剂萃取中的应用研究

概述了非离子型和离子型微乳液在溶剂萃取中的应用,并介绍了微乳液作为分离介质的萃取机理和静电作用模型．     

Dialysis of persistent organic pollutants and polycyclic aromatic hydrocarbons from semipermeable membranes. A procedure using an accelerated solvent extraction device

Accelerated solvent extraction (ASE) is one of the most recent solid-phase extraction methods and has caught on all over the world in numerous laboratories. Until now it was not known that this device is also very suitable for performing dialysis. In this study, development of a rapid dialysis procedure (RDP) was described that is based on the dialysis of persistent organic xenobiotics from triolein-containing semipermeable membrane devices (SPMDs) using ASE. All the operating parameters were optimized within the framework of usage. The RDP procedure was compared with the conventional dialytic recovery of target analytes under atmospheric pressure using spiked analytes and real field samples of SPMDs exposed to urban air. The main advantages of the RDP in comparison to the conventional dialysis are the speed, with up to 70 times faster taking only 40 min, and the considerable reduction in solvent consumption (by two-thirds) when SPMDs with standard configuration are used. Moreover, the RDP is also suitable as an analytical cleanup procedure for the same analytes from various types of lipid samples and other difficult matrixes using semipermeable membranes.     

Preconcentration and separation of nickel, copper and cobalt using solid phase extraction and their determination in some real samples

A solid phase extraction method has been developed to separate and concentrate trace amounts of nickel, cobalt and copper ions from aqueous samples for the measurement by flame atomic absorption spectrometry. By the passage of aqueous samples through activated carbon modified by dithioxamide (rubeanic acid) (DTO), Ni2+, Cu2+ and Co2+ ions adsorb quantitatively. The recoveries of analytes at pH 5.5 with 500 mg solid phase were greater than 95% without interference from alkaline, earth alkaline and some metal ions. The enrichment factor was 330. The detection limits by three sigma were 0.50 microg L(-1) for copper, 0.75 microg L(-1) for nickel and 0.80 microg L(-1) for cobalt. The loading capacity was 0.56 mg g(-1) for Ni2+, 0.50 mg g(-1) for Cu2+ and 0.47 mg g(-1) for Co2+. The presented procedure was applied to the determination of analytes in tap, river and sea waters, vegetable, soil and blood samples with successfully results (recoveries greater than 95%, R.S.D. lower than 2% for n=3).     

Bubbles in solvent microextraction: the influence of intentionally introduced bubbles on extraction efficiency

Significant improvements to microdrop extractions of triazine pesticides are realized by the intentional incorporation of an air bubble into the solvent microdroplet used in this microextraction technique. The increase is attributed partly to greater droplet surface area resulting from the air bubble being incorporated into the solvent droplet as opposed to it sitting thereon and partly to thin film phenomena. The method is useful at nanogram/liter levels (LOD 0.002-0.012 μg/L, LOQ 0.007-0.039 μg/L), is precise (7-12% at 10 μg/L concentration level), and is validated against certified reference materials containing 0.5 and 5.0 μg/L analyte. It tolerates water and fruit juice as matrixes without serious matrix effects. This new development brings a simple, inexpensive, and efficient preconcentration technique to bear which rivals solid phase microextraction methods.     

Kinetics of electrodialytic extraction of Pb and soil cations from a slurry of contaminated soil fines

The objective of this work was to investigate the kinetics of Pb-removal from soil fines during electrodialytic remediation in suspension, and study the simultaneous dissolution of common soil cations (Al, Ca, Fe, Mg, Mn, Na and K). This was done to evaluate the possibilities within control of the remediation process to leave a final product suitable for reuse. The Pb-remediation process could be divided into four phases: (1) a "lag-phase", (2) a period with a high removal rate (7.4 mg/day in average at 40 mA), (3) a period with a low removal rate, and (4) a period where no further Pb-removal was obtained. During the first phase, dissolution of carbonates was the prevailing process, resulting in a corresponding loss of soil mass. During this phase, the investigated ions accounted for the major current transfer, while, as remediation proceeded, hydrogen ions increasingly dominated the transfer. During phase (3) the high conductivity and low voltage suggested that removal may be accelerated by increasing the current density. Overall, 97% of the Pb could be extracted, reducing the final Pb-concentration to 25 mg/kg. The order of removal rates was: Ca>Pb>Mn>Mg>K>(Al and Fe).