沉积物内多氯联苯测定中有机氯农药的排除及质量控制/质量保证研究

报道了沉积物样品中多氯联苯(PCBs)的分析方法及质量控制/质量保证(QA/QC)研究,结果表明多级复合硅胶柱对有机氯农药去除效果良好.采用25种PCBs同族体标样PCB25对分析方法进行了QA/QC研究,PCBs的平均回收率在97%～118%之间.用本方法测定25种多氯联苯同族体的检测限范围在0.5～1.4ng/g之间.     

Development of a combined solid-phase extraction-supercritical fluid extraction procedure for the determination of polychlorinated biphenyls in wastewater.

A combined solid-phase extraction (SPE)-supercritical fluid extraction (SFE) procedure was developed for the analysis of polychlorinated biphenyls (PCBs) in wastewater. The importance of cleaning and drying the filters and SPE-disks prior to eluting PCBs with SFE was studied, leading to improved recoveries for all congeners investigated. The average PCB recovery of the final procedure, at a concentration of 18 ng/L in reagent water, was 101% with relative standard deviations ranging from 1 to 5% for the different congeners. Spiked leachate to a final concentration of 4 ng/L was extracted directly after spiking, or after 24 h of spiking. An average recovery of 112% was obtained in the direct extraction of spiked leachate.     

Dispersive liquid-liquid microextraction followed by gas chromatography–electron capture detection for determination of polychlorinated biphenyls in fish

A new method of dispersive liquid-liquid microextraction (DLLME) combined with GC-electron capture detection (GC-ECD) was proposed for the extraction and determination of four polychlorinated biphenyls (PCBs) congeners in fish samples. Acetone was used as extraction solvent for the extraction of PCBs from fish samples. The target analytes in the acetone solvent were rapidly transferred to chlorobenzene, which was used as extraction solvent in DLLME procedures. Under the optimum conditions, linearity was obtained in the concentration range from 1.25 to 1250 μg/kg for PCB 52, and 0.25 to 250 μg/kg for PCB 101, 138 and 153. Coefficients of correlation (r²) ranged from 0.9993 to 0.9999. The repeatability was tested by spiking fish samples at 10 μg/kg PCBs, and RSD% (n = 8) varied between 2.2 and 8.4%. The LODs were between 0.12 and 0.35 μg/kg. The enrichment factors of PCBs were from 87 to 123. The relative recoveries of the four PCB congeners for the perch, pomfret and yellow-fin tuna at spiking levels of 10, 20 and 50 μg/kg were in the range of 81.20–100.6%, 85.00–102.7% and 87.80–108.4%, respectively. The results demonstrated that DLLME combined with GC-ECD was a simple, rapid, and efficient technique for the extraction and determination of PCBs in fish samples.     

Pressurized liquid extraction in determination of polychlorinated biphenyls and organochlorine pesticides in fish samples

Pressurized liquid extraction (PLE) is a relatively new technique applicable for the extraction of persistent organic pollutants from various matrices. The main advantages of this method are short time and low consumption of extraction solvent. The effects of various operational parameters (i.e. temperature of extraction, number of static cycles and extraction solvent mixtures) on the PLE efficiency were investigated in this study. Fish muscle tissue containing 3.2% (w/w) lipids and native polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and other related compounds was used for testing. Purification of crude extracts was carried out by gel permeation chromatography employing Bio-Beads S-X3. Identification and quantitation of target indicator PCBs and OCPs was performed by high-resolution gas chromatography (HRGC) with two parallel electron-capture detectors (ECDs). Results obtained by the optimized PLE procedure were compared with conventional Soxhlet extraction (the same extraction solvent mixtures hexane–dichloromethane (1:1 v/v) and hexane–acetone (4:1 v/v) were used). The recoveries obtained by PLE operated at 90–120 °C were either comparable to “classic” Soxhlet extraction (for higher-chlorinated PCB congeners and DDT group) or even better (for lower chlorinated analytes). The highest recoveries were obtained for three static 5 min extraction cycles.     

Miniaturised sample preparation of fatty foodstuffs for the determination of polychlorinated biphenyls

A miniaturised analytical method allowing the exhaustive extraction of environmentally relevant polychlorinated biphenyls (PCBs) from fatty foodstuffs and the purification of the extracts in a single step has been developed. After dispersion of the freeze dried sample on silica modified with 44% (w/w) of sulphuric acid, the mixture was packed in a glass column on top of a multilayer silica column used for removal of the lipids and biogenic co-extracted material. Using this arrangement, a complete sample preparation can be accomplished by two successive 10 min static extractions with hexane followed by a brief dynamic step to ensure purging of the sample and sorbents. The analytical method showed a satisfactory performance, with recoveries of the endogenous PCBs studied in the 81-134% range of those found using a more conventional off-line procedure, even though as small an amount of sample as 0.1 g was used. Detection limits by gas chromatography with micro-electron capture detection (GC-ECD) were in all cases lower than 0.3 ng/g sample (freeze dried basis) and the repeatability of the complete analytical procedure better than 14% (except for PCB 167). When combined with GC and ion trap detection in the tandem mass spectrometry mode, the miniaturised method has been proved to be a valuable alternative to the more expensive high resolution mass spectrometry for fast screening of PCBs 77, 126, and 169, even if these congeners were not isolated from the bulk of PCBs.     

Comparison of Different Extraction Techniques of Polychlorinated Biphenyls from Sediments Samples

In this work, problems that may occur during determination of trace levels of polychlorinated biphenyls in sediment samples are described. Main error sources are connected with extraction of analytes prior to final determination.

During model studies, polychlorinated biphenyls have been extracted from sediment reference material (METRANAL 2) with the use of different solvents (dichloromethane, hexsane, and toluene); the process has been enhanced by mechanical shaking or ultrasounds. Seven selected PCBs (PCB 28, 52, 101, 118, 138, 153, and 180 – according to IUPAC) were determined in extracts samples by GC–MS technique.

During the studies, two calculation methods were applied to determine the amount of analytes introduced to the chromatographic column. The first approach assumes that the recovery of PCBs that contained a small amount of chlorine atoms in the molecule is similar to the recovery of ¹³C₁₂PCB28 standard, whereas compounds with greater number of chlorine atoms in the molecule will be recovered from the sediment similarly to the recovery of ¹³C₁₂PCB180 standard. The second approach assumes that the recovery of PCB 138 and PCB 153 is similar to the average value of ¹³C₁₂PCB28 and ¹³C₁₂PCB180 standards.

In the case of shaking assisted extraction, 55–90% PCB recoveries were achieved when toluene was used as a solvent, while 71–86% recovery was achieved when dichloromethane was used. When hexsane was used as solvent, recovery ranged 43–107%. In the case of ultrasounds assisted extraction, PCB recoveries of 50–108% were achieved when toluene was used as solvent, while 44–101% recovery was achieved when dichloromethane was applied. When hexsane was used as solvent, recovery reached 57–95%.

Studies have also shown that, when applying different isolation techniques and different solvents, the recovery of applied ¹³C₁₂PCB28 and ¹³C₁₂PCB180 standards is different. Recovery of ¹³C₁₂PCB28 standard was from 5% (for hexane tenfold extraction assisted by shaking) to 57% (for toluene tenfold extraction assisted by shaking). However, recovery of ¹³C₁₂PCB180 standard was from 9% (for hexane tenfold extraction assisted by shaking) to 82% (for toluene tenfold extraction assisted by shaking). This is due to the differences of their binding to the sludge matrix. Standard with a greater number of chlorine atoms in the molecule (¹³C₁₂PCB180) is more weakly associated with sediment than ¹³C₁₂PCB28 standard. In order to improve the accuracy of the results obtained, it is necessary to use labeled PCB compounds.     

Optimized method for the determination of 25 polychlorinated biphenyls in water samples using stir bar sorptive extraction followed by thermodesorption-gas chromatography/mass spectrometry

An optimized method using stir bar sorptive extraction (SBSE) for the determination of 25 polychlorinated biphenyls (PCBs) from water samples among them three of the most toxic coplanar PCBs (PCB 77, PCB 126 and PCB 169) was developed. Since the investigated PCBs comprise all steps of chlorination (from PCB 1 as monochlorobiphenyl to PCB 209 as decachlorobiphenyl) the results should be representative for the total class of the 209 PCB congeners. For 8 ml spiked water samples with 2 ml methanol addition and 2 h exposure time of stir bars recoveries between 28% (PCB 209) and 93% (PCB 1, PCB 52, PCB 77) were found. Detection limits between 0.05 ng/l and 0.15 ng/l were calculated for the combination of SBSE and thermodesorption-GC/MS. The procedure was applied to the investigation of groundwater and river water samples from the industrial region of Bitterfeld northern Leipzig, Germany.     

Rapid Chromatography for the Determination of Polychlorinated Biphenyls by GC-MS in Environmental Monitoring

A method for determination of polychlorinated biphenyls (PCBs) in environmental and biological materials has been developed. This method includes rapid chromatography requiring less than 10 min using an HT-8 capillary column at 30 m × 0.25 mm i.d. Rapid chromatography was performed using a column temperature gradient from 80 to 310°C at a rate of 40°C/min. Low-resolution mass spectrometry in single ion monitoring mode of simultaneous detection of 12 target ions is suggested for detection of PCBs peaks. The method not only enabled us to reduce time of analysis but also to increase the efficiency of separating PCB peaks from interferences and to reduce levels of detection of analytes resulting in a minimized sample preparation stage. The last includes extraction of the PCBs using organic solvents, preliminary alkaline hydrolysis in the case of biological objects, and cleaning up the extracts on compact cartridges. The method was tested in monitoring studies for these contaminants in soils, sediments, snow cover, fish tissues, and seal blubber. Total PCBs and isomer congener groups of the same chlorination degree and seven indicator congeners (IUPAC No.'s 28, 52, 101, 118, 138, 153, and 180) are determined with a high degree of certainty. The PCB concentrations were in the range of 1–700 ng/g dry weight for environmental samples and 500–25000 ng/g lipids for biota. The method yields measurements of total PCBs and isomer groups with a precision no greater than 10% and no greater than 15% for the indicator congeners.     

Diol sep-pak cartridges for enrichment of polychlorobiphenyls and chlorinated pesticides from water samples; determination by GC-ECD

Summary Gas chromatography of polychlorinated biphenyls and chlorinated pesticides in water samples has been performed after adsorption from a 20–200-mL sample on to a cartridge containing 100 mg diol-bonded porous silica. The PCBs are desorbed with 500 μL ethyl acetate, which is concentrated and analysed by gas chromatography with electron-capture detection (GC-ECD). The average recovery of 0.1 ng mL⁻¹ PCB congeners from distilled water and from Aniene river water is≥95% (standard deviation≤2.8). Average recoveries of 25 ng mL⁻¹ Aroclor 1254 from distilled water and from Aniene river water were, respectively, 94.4% and 92.5% (standard deviation 5.8). In the separation of PCB congeners from the chlorinated pesticides only the aldrin (40%) was eluted with the PCBs from the diol Sep-Pak cartridge by aqueous methanol. The method described is simple and reproducible.     

Graphitized carbons for solid-phase extraction

The objective of this review is to provide updated information about the most important features of graphitized carbonaceous sorbents used for solid-phase extraction (SPE) of organic compounds from liquid natural matrices or extracts. The surface characteristics of graphitized carbon blacks and porous graphitic carbons are described which are responsible for the various types interactions (hydrophobic, electronic and ion-exchange) with analytes. The method development is given which is based on the prediction from liquid chromatographic retention data obtained using porous graphitic carbon. Emphasis is placed on their capability for trapping very polar and water-soluble analytes from aqueous samples. Comparison is made between carbon-based SPE sorbents and other reversed-phase materials such as octadecyl silicas and highly cross-linked copolymers. Especially, the difficulty encountered for the desorption of some strongly retained analytes is explained by LC data and solutions are given for optimizing the composition and volume of the desorption solution. Many examples illustrate the various common features of graphitized carbons which are the extraction of very polar analytes and multiresidue extractions. Some applications are specific to graphitized carbon black due to the presence of surface functional groups. They include the extraction of anionic compounds such as benzene and naphthalene sulfonates or acidic pesticides. Other applications are specific to porous graphitic carbon due to its flat and homogeneous surface. One example is the trace extraction of coplanar polychlorinated biphenyls (PCBs), dibenzo-p-dioxins and dibenzofurans from other PCB congeners.     

Combined protocol for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) from sediments using focussed microwave assisted (FMW) extraction at atmospheric pressure

A microwave-assisted protocol has been developed using focussed microwaves at atmospheric pressure for the extraction of PAHs and PCBs from sediments. It combines extraction and purification assisted by microwaves. This protocol has been applied to the quantification of 12 individual PAHs, 8 individual PCBs and 8 PCB coeluted mixtures from two Standard Reference Materials and one natural sediment. The results for both classes of compounds (PAHs and PCBs) are good in terms of recoveries, which are always greater than 70% and in most cases around 100%. The reproducibility is also good with coefficients of variation below 10% in most cases. This protocol has the great advantage of saving time, the time dedicated to the preparation / extraction assisted by microwaves being reduced to less than half an hour.     

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.     

Simple solid-phase extraction method for determination of polychlorinated biphenyls and selected organochlorine pesticides in human serum

A simple off-line solid-phase extraction (SPE) method for isolation of polychlorinated biphenyls (PCBs) and selected organochlorine pesticides (OCPs) from human serum has been developed. The procedure includes denaturation of serum proteins by a mixture of water-1-propanol, application of the sample by aspiration twice repeatedly through the SPE column and elution with a mixture of n-hexane-dichlormethane. After final clean-up the compounds of interest were analysed by gas chromatography with micro-electron capture detection (GC-microECD). The recoveries achieved for PCB congeners using spiked porcine serum samples were 99-120% and for OCPs 88-115%. Relative standard deviations (RSD) ranged from 3 to 7%. The method was applied to real human serum samples and the recoveries of analytes in the serum were proportionally recalculated considering the recovery of the internal standard PCB-174. PCB-103 served as a syringe standard to correct volume of samples analysed. The aim of this study was to develop an effective off-line SPE procedure by optimization of existing SPE methods to supply laborious, solvent- and time-consuming liquid-liquid extraction (LLE) in routine analytical process.     

Combined protocol for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBx) from sediments using focussed microwave assisted (FMW) extraction at atmospheric pressure

A microwave-assisted protocol has been developed using focussed microwaves at atmospheric pressure for the extraction of PAHs and PCBs from sediments. It combines extraction and purification assisted by microwaves. This protocol has been applied to the quantification of 12 individual PAHs, 8 individual PCBs and 8 PCB coeluted mixtures from two Standard Reference Materials and one natural sediment. The results for both classes of compounds (PAHs and PCBs) are good in terms of recoveries, which are always greater than 70% and in most cases around 100%. The reproducibility is also good with coefficients of variation below 10% in most cases. This protocol has the great advantage of saving time, the time dedicated to the preparation / extraction assisted by microwaves being reduced to less than half an hour.     

Microwave assisted extraction and sonication of polychlorobiphenils from river sediments and risk assesment by toxic equivalency factors

Summary Microwave extraction and ultrasonication of dioxin-like polychlorobiphenyls (PCBs) from sediment samples were investigated. After separation of dioxin-like PCBs from a sample matrix on an acidic-alkaline silica gel column, dioxin-like PCBs were determined by GC-ECD, using dual capillary columns. Recoveries of dioxin-like PCBs in river sediment samples exceeded 80% by both extraction techniques. Toxic equivalency factors and their use for the PCB congeners investigated were applied. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997     

气相色谱-三重四极杆质谱同位素内标法测定鱼样中20种多氯联苯

建立了一种气相色谱-三重四极杆质谱结合双稳定性同位素内标检测鱼样中多氯联苯的方法。采用自动索氏提取器提取样品中的多氯联苯,经一根复合净化柱净化后,采用质谱多反应监测模式检测,选取两个独立的离子对。分析了20种多氯联苯,包含7种指示性多氯联苯,从三氯联苯到八氯联苯每族3个化合物,九氯联苯和十氯联苯各一个,每族使用一个相同氯代程度的¹³C₁₂标记多氯联苯作为定量内标、2种回收内标。20种多氯联苯在33 min内流出,分离良好,线性范围为0.05~10 μg/L,相关系数r均在0.99以上,低、中、高3种水平的加标回收率均在80.3%~117.6%之间,相对标准偏差（RSD,n=6）在5.09%~18.5%之间,方法检出限为0.01~0.02 μg/kg。20种多氯联苯总量在1.2~8.8 μg/kg（湿重）范围内,7个指示性多氯联苯总量在0.68~6.4 μg/kg（湿重）范围内。该方法缩短了分析时间,减少了有机溶剂的使用量,适合鱼样中多氯联苯的测定。     

Two new marine sediment standard reference materials (SRMs) for the determination of organic contaminants

Two new marine sediment standard reference materials (SRMs), SRM 1941b Organics in Marine Sediment and SRM 1944 New York/New Jersey Waterway Sediment, have been recently issued by the National Institute of Standards and Technology (NIST) for the determination of organic contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and chlorinated pesticides. Both sediment SRMs were analyzed using multiple analytical methods including gas chromatography/mass spectrometry (GC/MS) on columns with different selectivity, reversed-phase liquid chromatography with fluorescence detection (for PAHs only), and GC with electron capture detection (for PCBs and pesticides only). SRM 1941b has certified concentrations for 24 PAHs, 29 PCB congeners, and 7 pesticides, and SRM 1944 has certified concentrations for 24 PAHs, 29 PCB congeners, and 4 pesticides. Reference concentrations are also provided for an additional 58 (SRM 1941b) and 39 (SRM 1944) PAHs, PCB congeners, and pesticides. SRM 1944, which was collected from multiple sites within New York/New Jersey coastal waterways, has contaminant concentrations that are generally a factor of 10–20 greater than SRM 1941b, which was collected in the Baltimore (Maryland) harbor. These two SRMs represent the most extensively characterized marine sediment certified reference materials available for the determination of organic contaminants.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

贻贝中多氯联苯分析的前处理方法研究

针对分析贻贝中痕量多氯联苯（PCBs），比较了索氏提取（SE）和加速溶剂萃取（ASE）两种提取方法，结果表明SE对贻贝中7种PCBs（PCB28、PCB52、PCB101、PCB118、PCB153、PCB138、PCB180）回收率范围在96％～125％，ASE回收率范围在102％～115％，两者提取效果相当，但与索氏提取相比，加速溶剂萃取是一种怏速、高效的提取方法此外采用凝胶渗透色谱（GPC）分别与Florisil和C18固相萃取（SPE）小柱联用净化，GPC与Florisil柱联用净化的凹收率范围在90％-112％，GPC与C18柱联用净化的回收率范围在74％-108％，结果表明GPC与Florisil柱联增净化优于GPC与C18柱联用净化。     

Simultaneous microwave-assisted extraction of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phthalate esters and nonylphenols in sediments

A new method was developed for the simultaneous extraction of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), phthalate esters (PEs), nonylphenols (NPs) and nonylphenol mono- and diethoxylates (NP1EOs and NP2EOs, respectively) in sediment samples by means of a closed microwave system. The extractions were carried out at 21 psi and 80% of microwave power and 15 ml of acetone were used as the common extraction solvent. The filtered extract was further fractionated in two groups using Florisil cartridges: PAHs and PCBs were eluted with n-hexane:toluene (4:1) and the PEs, NPs and ethoxylates were eluted with ethyl acetate. All the compounds were analysed by gas chromatography-mass spectrometry (GC-MS). In case of PAHs and PCBs, the developed method was validated by comparison of the results obtained for the certified reference material NIST 1944 with the certified values. In the absence of a reference material for phthalate esters and nonylphenols, one sediment sample was extracted twice under the optimal conditions in order to check than an exhaustive extraction of the analytes occurred. This method is currently used in the study of the distribution of those organic contaminants in the estuaries of the Bay of Biscay (Spain).     

Determining PCB desorption behaviour on sediments with SFE and investigating the dependency of selective fractions on sediment characteristics

A method for studying PCB desorption behaviour from sediments using supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) is presented. Four sediments were investigated and extracted with supercritical carbon dioxide employing increasingly harsher extraction conditions ranging from 40°C and 12?MPa to 100°C and 36.5?MPa. To ensure quantitative extractions, the remaining SFE residues were also extracted with PLE. Resulting profiles identified at least three different PCB fractions within the four sediments. Furthermore, a distinct fraction was obtained with extraction for 2?h at 40°C and 36.5?MPa. This fraction has previously been found to correlate well with bioavailable fractions. The dependency of this fraction on sediment total organic carbon (TOC) was investigated, both for sediments examined in this study as well as for previously reported values using the same extraction conditions. It was found that TOC does not correlate to selective SFE, which indicates that the use of TOC to predict bioavailability is questionable.