Selective pressurized liquid extraction of polychlorinated biphenyls from fat-containing food and feed samples influence of cell dimensions, solvent type, temperature and flush volume

Sulphuric acid impregnated silica was used for the lipid free extraction of polychlorinated biphenyls from fat containing food and feed matrices using pressurized liquid extraction on a Dionex ASE300, with 34 mL cells. Data were compared to a previous publication where extractions had been performed on a Dionex ASE200, with 33 mL cells. Four different fat/fat retainer ratios (FFRs) were tested (0.100, 0.075, 0.050 and 0.025) at 50 and 100 degrees C using n-pentane, n-hexane or n-heptane as extraction solvent. The best results were obtained with a FFR of 0.025 when applying a temperature of 100 degrees C. Both n-pentane and n-heptane were capable of replacing n-hexane as extraction solvent. A flush volume of 60% was sufficient as suggested in US Environmental Protection Agency Method 3545. The applicability of the method was demonstrated for naturally contaminated fish meal as well as various spiked and certified materials.     

Selective Pressurized Liquid Extraction of PCB’s from Food and Feed Samples: Effects of High Lipid Amounts and Lipid Type on Fat Retention

Fat free extraction of polychlorinated biphenyls (PCBs) from fat containing food and feed matrices was achieved by selective pressurized liquid extraction using sulphuric acid impregnated silica inside 100 mL extraction cells on a Dionex ASE300. Data were compared to previous publications where extractions had been performed on a Dionex ASE200, with 33 mL cells and a Dionex ASE300, with 34 mL. In all extractions a high lipid amount of 1,500–3,000 mg was used in the extractions. Seven different fat/fat retainer ratios (FFRs) were tested (0.200, 0.150, 0.100, 0.075, 0.050, 0.040 and 0.025) at 100 and 150 °C using n-heptane as extraction solvent. The FFR ratio differed between triglycerides and fish oil in that fat free extracts were obtained at FFR of 0.050 for fish oil at 150 °C but 0.040 for fish triglycerides. When the extraction temperature was lowered to 100 °C a FFR ratio of 0.050 resulted in fat free extracts for both matrices. These data differ from previous studies, on ASE200 33 mL cells and ASE300 34 mL cells, were both matrices required a FFR of 0.025. The influence on the PCB recovery of these higher amounts of lipids in the extraction cells was tested by spiking triglycerides and fish oil with PCBs and extracting them with FFR-values of 0.025, 0.040 and 0.050. This showed that there was no difference in the PCB recovery and thus allowing a higher amount of lipids in each extraction cell when a FFR ratio of 0.050 could be used. The method was also tested on naturally contaminated cod liver homogenate, naturally contaminated cod liver oil spiked to feed for poultry, as well as certified reference materials (Cod liver oil BCR 349 and Spiked pork fat IRMM 445).     

Optimised accelerated solvent extraction of PCBs and PAHs from compost

This study is the first thorough method optimisation for accelerated solvent extraction (ASE) of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) from chemically dried compost. For PCBs, optimised solvent composition, temperature, pressure, number of static cycles, duration, and flush volume were as follows: toluene/acetone 1?:?3 (v/v), 120°C, 2000?psi, 3?×?5?min, and 50%, respectively. Limits of quantification and method precision were between 0.16 and 2.46?µg?kg^?1 dw and 6–17% respectively for individual PCBs. Absolute recoveries of isotope-labelled extraction standards used for each of the analytes ranged from 65 to 105% and relative recoveries were between 85 and 99%. The method proofed to be robust and was successfully applied to different compost samples.

The optimisation of PAHs extraction was performed and resulted in the following conditions: solvent: hexane/acetone 1/3 (v:v), temperature: 140°C, pressure: 1500?psi, extraction time: 3?×?5?min, and 50% flush volume. Limits of detection and method precision for individual PAHs were between 1.1 and 37.2?µg?kg^?1?dw and 12–34% respectively. Absolute and relative recoveries ranged from 24 to 68% and from 85 to 99%, respectively. Optimal extraction conditions for PAHs were more difficult to determine due to the inhomogeneous distribution of PAHs in samples. However, the method appeared to be feasible and suggestions for further improvements are presented.     

Effect of temperature and solvent composition on extraction of fumonisins B1 and B2 from corn products

Fumonisins B1 and B2 were extracted from naturally contaminated corn products by using different extraction solvent compositions (methanol-water, acetonitrile-methanol-water, ethanol-water, and 100% water) and a range of temperatures from ambient to 150 degrees C. Ground samples of several corn products and 1 rice sample were mixed with an adsorbent material (Hydromatrix), and the fumonisins were extracted in 2 sequential 5 min static extractions at various temperatures. The combined extracts were cleaned up and analyzed by reversed-phase liquid chromatography with fluorescence detection after o-phthaldialdehyde-mercaptoethanol derivatization. The results showed a clear influence of temperature and solvent composition on recovery of fumonisins from some matrixes. With acetonitrile-methanol-water (1 + 1 + 2) the quantity of fumonisins extracted from naturally contaminated taco shells almost tripled in going from 23 degrees to 80 degrees C, and increased by another 30% when ethanol-water (3 + 7) was used as extraction solvent at 80 degrees C. Similar results were obtained with nacho chips. These effects were less pronounced with cornmeal, and small differences due to temperature and solvent composition were observed for corn flakes and rice. The ethanol-water extraction solvent combinations were specifically evaluated in an effort to use the cheapest, least toxic, and most environmentally friendly solvents for organic residue analysis. At 80 degrees C, ethanol-water combinations performed equally or better than methanol-water (8 + 2) or acetonitrile-methanol-water (1 + 1 + 2), combinations which are commonly used for fumonisin extractions. Even 100% water was successful for extracting fumonisins from the products, except for rice. However, increased amounts of water created technical problems and required an increased amount of Hydromatrix in the samples prior to extraction.     

Selective pressurized liquid extraction of polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls from food and feed samples

Selective pressurized liquid extraction (PLE) of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) from various food and feed samples was performed with a selective PLE method previously developed for bulk PCBs. The method utilizes sulfuric acid impregnated silica inside the extraction cell to oxidize coextracted fat. Extractions were performed at 100 degrees C with n-heptane for 5 min in two cycles. Data obtained by selective PLE combined with gas chromatography/high-resolution mass spectrometry (GC-HRMS) were compared to concentrations derived from reference laboratories applying conventional sample preparation and GC-HRMS. Experiments performed on spiked vegetable oil, naturally contaminated crude fish oil and oil containing compound feed samples showed good results for these relatively simple matrices. The accuracy was generally +/-20% as compared to spiked levels or to values obtained by the reference laboratories. The precision, measured as the relative standard deviation (RSD) for 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalency values (TEQs), was below 10% in all cases. The method was also tested on naturally contaminated herring tissue, chicken tissue, pork tissue and sepiolitic clay, which all caused some trouble. It was observed that sufficient amounts of sodium sulfate should be used for dehydration of tissue samples and additionally, the cells should not be packed too dense in order to avoid suppressed extraction efficiency. Once this was attended to, satisfactory data could be obtained, except for sepiolithic clay. This study demonstrates that selective PLE can be applied with success to a number of food and feed matrices in analysis of PCDD/Fs and dl-PCBs. Since the fat removal step is on-line, the selective PLE method will reduce time and solvent consumption for sample preparation as compared to traditional clean-up.     

Assisted solvent extraction and ion-trap tandem mass spectrometry for the determination of polychlorinated biphenyls in mussels. Comparison with other extraction techniques

A selective and sensitive analytical method for determination of ten congeners of polychlorinated biphenyls (PCBs 31, 28, 52, 101, 118, 153, 105, 138, 156, and 180) in mussel samples (Mytilus galloprovincialis) based on accelerated solvent extraction (ASE) and gas chromatography–tandem mass spectrometry (GC–MS–MS) is presented in this work. Extraction conditions were optimised using a Plackett–Burman factorial design. The final extracts were analysed after cleanup on alumina columns. The optimised extraction parameters were solvent percentage, sample amount, extraction temperature, pressure, static extraction time, flush percentage, and purge time. The results suggest that PCBs 118, 105, and 180 extractions appeared affected by only one statistically significant factor, pressure, solvent percentage and static extraction time, respectively. Extraction of PCBs 138 and 156 was affected by amount of sample. PCB 138 extraction was also statistically affected by static extraction time and purge time. Quantitative recoveries (64.8–120.3%) were achieved for all PCBs and method precision (RSD < 19%) was satisfactory.     

Optimization of a microwave-assisted extraction method for the analysis of polychlorinated biphenyls in ash samples

An alternative method for the extraction of polychlorinated biphenyls (PCBs) in ash samples, which is less time and solvent consuming than Soxhlet extraction, is presented. A study was carried out to evaluate the possibilities of microwave-assisted extraction (MAE) to determine exactly which parameters affect the efficiency of the process, since direct extrapolation of extraction conditions for PCBs in other solid matrices, failed when applied to coplanar congeners in ash samples. Influence of the organic solvent on the yield of the extraction was first evaluated using two ash samples with different percentages of carbon. Once the extraction solvent was fixed, the effects of solvent volume, extraction temperature and extraction time were investigated using an experimental design. It was found that the volume of organic solvent played a more important role in the extraction efficiency than the other factors. In the optimal conditions microwave extractions were performed at 110 degrees C. for 10 min and using 30 ml of toluene. Recoveries higher than 80% were obtained for all the highly chlorinated congeners. including coplanar species, in a spiked ash sample containing a relatively high concentration of carbon. The proposed method was also applied to the determination of PCBs in a reference material of urban dust. Recoveries were similar to those obtained for spiked ash samples.     

Pressurized liquid extraction followed by high-performance liquid chromatography for determination of seven active compounds in Cortex Dictamni

A new method based on pressurized liquid extraction (PLE) followed by a sensitive and specific HPLC-DAD analysis is developed for determination of seven compounds in Cortex Dictamni. The operational parameters of PLE, such as extraction solvent, extraction temperature, extraction pressure, static extraction time, flush volume and extraction cycles were optimized, using the extraction efficiencies of dictamnine, obacunone and fraxinellone as targets. The optimized procedure employed MeOH as extraction solvent, 150 degrees C of extraction temperature, 1,500 psi extraction pressure, 5 min of static extraction time, 60% flush volume and the extraction recoveries of the three compounds were nearly to 100% for only one cycle. The following HPLC analysis was performed on a reversed-phase C(18) column with methanol-water as mobile phase in gradient manner, detected at 236 and 218 nm. The limits of detection (LOD) and limits of quantification (LOQ) of the seven compounds were in the range of 0.4-15.6 ng and 1.2-38.8 ng. This assay can be readily utilized as a quality control method for Cortex Dictamni and other related medicinal plants.     

Optimization of pressurized liquid extraction (PLE) of dioxin-furans and dioxin-like PCBs from environmental samples

Pressurized liquid extraction (PLE) applying three extraction cycles, temperature and pressure, improved the efficiency of solvent extraction when compared with the classical Soxhlet extraction. Polychlorinated-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like PCBs (coplanar polychlorinated biphenyls (Co-PCBs)) in two Certified Reference Materials [DX-1 (sediment) and BCR 529 (soil)] and in two contaminated environmental samples (sediment and soil) were extracted by ASE and Soxhlet methods. Unlike data previously reported by other authors, results demonstrated that ASE using n-hexane as solvent and three extraction cycles, 12.4 MPa (1800 psi) and 150 degrees C achieves similar recovery results than the classical Soxhlet extraction for PCDFs and Co-PCBs, and better recovery results for PCDDs. ASE extraction, performed in less time and with less solvent proved to be, under optimized conditions, an excellent extraction technique for the simultaneous analysis of PCDD/PCDFs and Co-PCBs from environmental samples. Such fast analytical methodology, having the best cost-efficiency ratio, will improve the control and will provide more information about the occurrence of dioxins and the levels of toxicity and thereby will contribute to increase human health.     

Simultaneous extraction of several persistent organic pollutants in sediment using focused ultrasonic solid-liquid extraction

Focused ultrasonic solid-liquid extraction (FUSLE) has been optimised for simultaneous analysis of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), phthalate esters (PEs), and nonylphenols (NPs) in sediment samples. Optimisation was performed using naturally polluted freeze-dried sediment samples. The variables studied during the optimisation process were: percentage of maximum power (10-60%), extraction time (10-300 s), number of cycles (1-9), composition of the extraction solvent (acetone-n-hexane, 10:90-90:10), and sample mass (0.1-1 g). The volume of the extractant was constant (10 mL) and the extraction was performed at 0 degrees C in an ice-bath during the optimisation process. All these variables were studied using an experimental design approach by means of The Unscrambler software. The extraction time and the operational variables (number of cycles and power) had no statistically significant effect in the extraction and they were held at 2 min, 20% power, and seven cycles, respectively. The mass and the addition of non-polar solvent (n-hexane) had a negative effect in the extraction yield and, thus, the mass was held at 0.5 g and pure acetone was used as extraction solvent. After those variables were optimised, the effect of the extraction temperature (0 degrees C or room temperature) was also studied. The validation of the extraction method was performed using NIST-1944 reference material in the case of PAHs and PCBs. Because no certified reference sediment is available for PEs and NPs, the results obtained for FUSLE were compared with those obtained for microwave-assisted extraction (MAE) under conditions optimised elsewhere. In all the cases the analysis were performed by gas chromatography-mass spectrometry (GC-MS). Good accuracy were achieved in all cases. The limits of detection (LODs) obtained were between 0.10 and 1.70 ng g(-1) for PAHs (except for naphthalene 5.33 ng g(-1)), 0.02 and 0.16 ng g(-1) for PCBs, 46 and 188 ng g(-1) for PEs, and 0.6 and 12.4 microg g(-1) for NPs. The precision was around 5-10% for most of the PAHs and PCBs and around 2-10% for most of the PEs and NPs.     

On-line clean-up of pressurized liquid extracts for the determination of polychlorinated biphenyls in feedingstuffs and food matrices using gas chromatography-mass spectrometry

This paper describes a fast and simple pressurized liquid extraction method for the determination of polychlorinated biphenyls (PCBs) in feedingstuffs and food matrices. The method is based on a simultaneous extraction/clean-up step requiring a minimum of sample handling. The final analysis was performed with gas chromatography-mass spectrometry. Seven PCBs (28, 52, 101, 118, 138, 153 and 180) were analyzed, all of which are indicator congeners that, according to European legislation should be included in the analytical monitoring program. The extracted matrices were spiked feed for poultry and two certified reference materials naturally contaminated with PCBs (cod-liver oil and milk powder), which showed excellent conformity with certified data.     

Pressurised liquid extraction of flavonoids in onions. Method development and validation

A rapid and reliable analytical method for quantification of flavonoids in onions was developed and validated. Five extraction methods were tested on freeze-dried onions and subsequently high performance liquid chromatography (HPLC) with UV detection was used for quantification of seven flavonoids.The extraction efficiencies were lowest for the conventional water bath extraction compared to pressurized liquid extraction (PLE), ultrasonication, ultrasonic liquid processor, and microwave extraction, which yielded similar efficiencies. The reproducibility was in the same range (RSD: 1-11%) for all tested extraction methods. However, PLE was the preferred extraction method because the method can be highly automated, use only small amounts of solvents, provide the cleanest extracts, and allow the extraction of light and oxygen-sensitive flavonoids to be carried out in an inert atmosphere protected from light.The method parameters: extraction temperature, sample weight, flush volume and solvent type were optimised, and a clean-up step was integrated in the PLE procedure by in-cell addition of C18-material to the extraction cells, which slightly improved the recovery and reproducibility of the method. The one-step PLE method showed good selectivity, precision (RSDs = 3.1-11%) and recovery of the extractable flavonoids (98-99%). The method also appeared to be a multi-method, i.e. generally applicable to, e.g. phenolic acids in potatoes and carrots.     

Optimization of Soxtec Extraction for the Determination of Polychlorinated Biphenyls (PCBs) in Mussel and Comparison with Soxhlet Extraction,Accelerated Solvent Extraction,and Microwave Assisted Extraction

An on-line Soxtec extraction and cleanup method is optimized for PCBs determination in mussel samples. Soxtec extraction conditions have been optimized using two factorial designs. Optimized extraction parameters were sample weight, anhydrous sodium sulfate weight, solvent volume, alumina weight, and boiling and rinsing times. The results suggest that all PCBs congeners extracted by Soxtec appeared statistically affected by solvent volume. Soxtec quantitative recoveries (8– ?115%) were achieved for all PCBs and method precision (RSD <12%) was satisfactory. The optimized method is compared with three different applied extraction methods, Soxhlet, accelerated solvent extraction, and microwave-assisted extraction. This latter presents the cleanup step on column or assisted by polypropylene membranes. The extraction effectiveness of the four different applied extraction methods for the determination of PCBs in mussel was similar.     

Dispersive liquid-liquid microextraction based on the solidification of floating organic droplet for the determination of polychlorinated biphenyls in aqueous samples

In the proposed method, an extraction solvent with a lower toxicity and density than the solvents typically used in dispersive liquid-liquid microextraction was used to extract seven polychlorinated biphenyls (PCBs) from aqueous samples. Due to the density and melting point of the extraction solvent, the extract which forms a layer on top of aqueous sample can be collected by solidifying it at low temperatures, which form a layer on top of the aqueous sample. Furthermore, the solidified phase can be easily removed from the aqueous phase. Based on preliminary studies, 1-undecanol was selected as the extraction solvent, and a series of parameters that affect the extraction efficiency were systematically investigated. Under the optimized conditions, enrichment factors for PCBs ranged between 494 and 606. Based on a signal-to-noise ratio of 3, the limit of detection for the method ranged between 3.3 and 5.4 ng L⁻¹. Good linearity, reproducibility and recovery were also obtained.     

The Extraction of Polycyclic Aromatic Hydrocarbons from Atmospheric Particulate Matter Samples by Accelerated Solvent Extraction (ASE)

Abstract

The Accelerated solvent extraction (ASE) of PAHs (23 2- to 6-ring species) spiked onto glass fibre filters (GFFs) was studied as a function of variable extraction solvents, pressure, temperature and extraction times. Acceptable recoveries (85% ± 15%) were obtained for certain combinations of conditions and a tentative method (1500 psi, 150°C, 70:30 hexane:acetone mixture, 7 min heat-up time, 5 min static extraction time, 60% flush volume, 2 static cycles was selected for further testing. However, this method did not prove as effective as the traditional Soxhlet method of extraction when these parameters were used to extract native PAHs from ambient atmospheric particulate matter collected on a GFF by Integrated Atmospheric Deposition Network (IADN) sampling protocols. The extraction recovery study for spiked GFFs was repeated using slightly different extraction conditions: 2000 psi, 100°C, 70:30 hexane:acetone, 5 min heat-up time, 5 min static extraction time, 150% flush volume, 3 static cycles. When this method was applied to the extraction of native PAHs from ambient atmospheric particulate matter collected on GFFs, the results showed equivalent or better recoveries to that of the Soxhlet method. The total time of extraction was 25 min requiring only 30 mL of solvent. This ASE method is presently used to quantitatively determine PAHs in IADN particle-phase samples.     

Gas chromatographic/mass spectrometric determination of flumioxazin extracted from soil and water

A method was developed for determining flumioxazin in soil and water. Recovery efficiencies for solid-phase extraction (SPE) of flumioxazin from deionized, well, and surface water were between 72 and 77%. SPE was superior to liquid-liquid extraction, using water-hexane and water-chloroform emulsions, which resulted in retrieval efficiencies of 25 and 22%, respectively. However, liquid-liquid extraction with ethyl acetate improved recovery of total flumioxazin to >64%. Extraction from soil samples by direct solvent/soil extraction methods recovered between 18 and 76% of applied flumioxazin, depending on the solvent combination used. However, the use of accelerated solvent extraction techniques resulted in a 106 +/- 8% recovery of flumioxazin from soil. In analysis by capillary gas chromatography with mass selective detection, flumioxazin had a calculated limit of detection of 9 ng/mL with a retention time of 16.66 min.     

Determination of selected polychlorinated biphenyls in soil by miniaturised ultrasonic solvent extraction and gas chromatography-mass-selective detection

Miniaturised ultrasonic solvent extraction procedure was developed for the determination of selected polychlorinated biphenyls (PCBs) in soil samples by gas chromatography-mass-selective detection by using 2³ factorial experimental design. Recoveries of PCBs from fortified soil samples are over 90% for three different fortification levels between 40 and 120 μg kg⁻¹, and relative standard deviations of the recoveries are below 7%. The limits of detection (LODs) ranged from 0.003 to 0.006 μg kg⁻¹. The performance of the proposed method was compared to traditional shake flask extraction method on the spiked real soil sample and extraction methods showed comparable efficiencies. Proposed miniaturised ultrasonic solvent extraction offers several advantages, i.e., reducing sample requirement for measurement of target compound, less solvent consumption and reducing the costs associated with solvent purchase and waste disposal.     

Pressurised liquid extraction of polycyclic aromatic hydrocarbons from contaminated soils

The reliability and efficiency of the pressurised liquid extraction technique (PLE) for extracting polycyclic aromatic hydrocarbons (PAHs) from contaminated soil has been investigated. Experimental design was used to study the influence of seven extraction variables (sample load, solvents used, solvent ratios, pressure, temperature, extraction time, and rinse volume). The results show that large sample loads in combination with small solvent volumes may result in low extraction efficiency. They also indicate that the recovery of low-molecular-mass PAHs is reduced by low extraction temperatures. The exact settings of the other variables are, however, less significant for the extraction efficiency. Repeated extractions at optimised settings of the tested variables show that PLE is an exhaustive extraction technique that generally results in high yields. In addition, extraction of a certified reference material (CRM 103-100) revealed that the method is both accurate and precise. Another finding was that adding the internal standard on top of the soil in the extraction cell causes considerable over-estimation of the concentrations when large samples are extracted with small solvent volumes. This is because the PLE-cell resembles a chromatographic column, so compounds added to the top of the soil layer have a longer distance to travel through the soil compared to the average distance of the native compounds, which are distributed evenly throughout the column. We therefore recommend that the internal standard should be added to the extract immediately after the extraction or, alternatively, carefully mixed with the sample prior to extraction.     

加速溶剂提取-同位素稀释-高分辨气相色谱-高分辨质谱法测定生物样品中82种多氯联苯

我国水产品中多氯联苯(PCBs)的检测方法,主要以6种指示性PCBs和12种二噁英类共平面PCBs为主,仅涵盖有限的PCBs。为更全面地获得生物体中PCBs的浓度水平,深入探讨PCBs在生物体内的代谢和富集特征,进而准确评价PCBs对人类的暴露水平及风险,以鱼和贝类作为生物样品代表,建立了加速溶剂提取-同位素稀释-高分辨气相色谱-高分辨质谱(ASE-ID-HRGC-HRMS)测定生物样品中82种PCBs的方法。比较了振荡提取和加速溶剂提取两种提取方式的回收率和重复性,最终采用正己烷-二氯甲烷(1∶1, v/v)对PCBs进行加速溶剂提取。考察了各流分淋洗液对PCBs的回收率,确定了样品提取液经8 g 44%酸性硅胶层析柱(内径15 mm), 90 mL正己烷洗脱的净化方式。样品提取液净化浓缩后进行HRGC-HRMS分析,色谱柱采用DB-5MS超低流失石英毛细管柱(60 m×0.25 mm×0.25 μm)。通过优化后的升温程序对化合物进行分离,以保留时间和两个特征离子精准定性,采用同位素内标法定量。结果表明,在0.1~200 μg/L范围内,平均相对响应因子(RRF)的相对标准偏差值(RSD, n=7)均≤20%,相关系数(r²)>0.99。生物样品中PCBs的方法检出限为0.02~3 pg/g;鱼类中PCBs平均加标回收率为71.3%~141%, RSD(n=7)为2.1%~14%;贝类中PCBs平均加标回收率为76.9%~143%, RSD为1.4%~11%。该方法灵敏、准确、可靠,可以更加全面具体地分析鱼和贝类等水产品受PCBs的污染情况,为国内外开展生物监测提供有效的技术支持,从而服务于相关生态环境管理及履行《斯德哥尔摩公约》。     

Optimisation and comparison of microwave-assisted extraction and Soxhlet extraction for the determination of polychlorinated biphenyls in soil samples using an experimental design approach

Optimisation of microwave-assisted extraction (MAE) for the extraction of polychlorinated biphenyls (PCBs) from soil samples has been accomplished using an experimental design approach. Variables studied have been: percentage of acetone (v/v) in an acetone:n-hexane mixture, solvent volume, extraction time, microwave power and pressure inside the extraction vessel. Five samples of a certified soil (CRM 481) have been extracted under the optimum conditions of the developed method and the results have been compared to those obtained by Soxhlet extraction. Good recoveries (>95%) have been obtained for all the PCBs studied. All extracts have been analysed by gas chromatography/mass spectrometry (GC/MS) and an optimum determination method for the electron impact mass spectrometric (EIMS) has also been developed.