Optimised chromatographic method for the measurement of selected polychlorinated biphenyls in ambient air

The focus of this study was to optimise selected polychlorinated biphenyl analysis in air by gas chromatography. Sample preparation was improved by using an automatic solid/liquid extraction system and columns with 1.5 g of Florisil for cleaning extracts. Better precision on clean-up results was obtained from Florisil cartridges, when compared to those obtained with silica gel. Analytical procedure was checked by participating in an inter-comparison exercise. Finally, we have considered usefulness of evaluating uncertainties associated to our method because of the large handling samples and the extremely low concentrations of PCBs in ambient air.     

Intercomparison study for the determination of selected polychlorinated biphenyls (PCBs) in feed matrices

Analytical methodology currently employed for the determination of seven indicator PCBs in three compound feeds and fish meal has been evaluated in a collaborative study. The majority of the obtained relative standard deviations of the PCBs varied from 20 to 30%. On assuming a target relative standard deviation of 22% for the analytical results, statistical evaluation showed that about 80% of the participating laboratories delivered data within an acceptable range of +/- 44% of the assigned concentration in the test materials. However, between 10 and 20% of the participating laboratories reported unacceptable results. Major problems seemed to arise from insufficient separation of PCB congeners, low extraction efficiency, and calculation errors. Correct identification of the target PCB congeners was a prevalent problem if only one capillary column in combination with an electron capture detector (ECD) was employed. The correct preparation of the calibration solution by the laboratories turned out to be only a minor problem. The laboratories participating in this study employed quite different techniques at all stages of the analytical procedure. Principal component analysis indicated that laboratories using an internal standard tended to report higher values for the target analytes. If the PCB concentrations were related to the fat content of the sample, the variability of the reported results decreased for compound feed but increased for fish meal. These inconsistent results are probably due to the fact that fat is not an objective parameter but is defined by the analytical technique employed. It is assumed that harmonizing analytical methods for the determination of this parameter could improve the precision of the PCB results.     

Determination of polychlorinated biphenyls in ambient air by gas chromatography coupled to triple quadrupole tandem mass spectrometry

A multiresidue method for determining 22 polychlorinated biphenyls (PCBs) in air has been developed and validated by gas chromatography (GC) coupled to tandem mass spectrometry (MS/MS) using a triple quadrupole analyzer (QqQ). The method was validated in terms of both steps of sampling and analysis. The sampling method, which is based on active sampling using polyurethane foam (PUF) as adsorbent, was validated by generating standard atmospheres. The retention capacity of this sampling sorbent allows up to 5 m³ of air to be sampled without any breakthrough for most compounds. Two solvent extraction methods were compared: sonication and Soxhlet extraction with a mixture of n-hexane:diethyl ether (95:5 v/v). Both extraction methods yielded similar results, but the first one required less solvent and time. The method exhibited good accuracy (80.3–99.8%), precision (2.2–15.2%) and lower limits that allowed quantification and confirmation at levels as low as 0.008 ng/m³. Finally, the method was applied to the analysis of PCBs in the air in areas near to a municipal solid-waste landfill and directly above the refuse in the landfill, where it indicatedd the presence of some of the target compounds. Figure General chemical structure of polychlorinated biphenyls     

High-throughput analysis of human serum for selected polychlorinated biphenyls (PCBs) by gas chromatography-isotope dilution time-of-flight mass spectrometry (GC-IDTOFMS)

A method for the high-throughput analysis of human serum for the 38 most prevalent polychlorinated biphenyls (PCBs) based on the use of fast gas chromatography-isotopic dilution time-of-flight mass spectrometry (GC-IDTOFMS) is presented. The chromatographic separation time was 8 min. The separation of the congeners was carried out either chromatographically or analytically using the mass spectral deconvolution capability of the TOFMS. The instrument and the method limits of detection (LODs) were 0.5 pg microL(-1) and 20 pg microL(-1), respectively, which is not as good as the one achieved using high resolution mass spectrometry (HRMS) but allows the detection and quantification of the prevalent PCBs present in real human serum samples. The dynamic range covered 3 orders of magnitude. The comparison with the high resolution mass spectrometry (HRMS) reference method (28 min) was good and some separation improvements have been observed. This method allows the analysis of 100 samples per day per instrument.     

A new fast method for field screening of polychlorinated biphenyls in air

A new fast method for the detection of a sum parameter for polychlorinated biphenyls in air is presented. Air pollutants are sampled on a thermodesorbable silicone-coated glass fibre filter. Analysis is carried out by a mobile GC-MS system with short GC columns. Total time for analysis in the field is about 10 min. A novel data evaluation is used for quantification. To evaluate the GC run, signals of the characteristic ion traces of each degree of chlorination are integrated. Superposition of ion fragments in the low-resolution GC run are eleminated by a special algorithm.     

Particle size distribution of metals in the atmosphere of Madrid (Spain)

Summary The size distribution of six metals (Cd, Cu, Fe, Mn, Ni and Pb) present in the atmosphere of Madrid was determined in the airborne particulate matter. Samples were collected in an area located in the University Campus in Madrid. Twenty-one samplings were carried out in two different periods: summer 1986 and autumn — winter 1986–87. AAS was employed in the analysis. The particle size distribution of the elements was bimodal. The most toxic metal studied (Cd, Ni and Pb) have extremely high proportions in the smallest particle size range, which can easily enter the respiratory tract lodging in the alveoli. For the metals the enrichment factors based on soil proportions are calculated on each stage. The values are higher for lead, cadmium and nickel, tending to vary from stage to stage, suggesting significant pollution sources.     

Determination of selected polychlorinated biphenyls in water samples by ultrasound-assisted emulsification-microextraction and gas chromatography-mass-selective detection

Ultrasound-assisted emulsification-microextraction (USAEME) procedure was developed for the determination of selected polychlorinated biphenyls (PCBs) in 10 mL of water samples by gas chromatography-mass-selective detection. After determination of the most suitable solvent and extraction time, several other parameters including solvent volume, centrifugation time and ionic strength of the sample were optimized using a 2³ factorial experimental design. The optimized USAEME procedure used 200 μL of chloroform as extraction solvent, 10 min of extraction with no ionic strength adjustment at 25 °C and 5 min of centrifugation at 4000 rpm. The limits of detection ranged from 14 ng L⁻¹ (for PCB153) to 30 ng L⁻¹ (for PCB101). Recoveries of PCBs from fortified distilled water are over 80% for three different fortification levels between 0.1 and 5 μg L⁻¹ and relative standard deviations of the recoveries are below 10%. The performance of the proposed method was compared with those involving traditional liquid-liquid extraction (LLE) and solid phase extraction (SPE) on the real water samples (i.e., tap and well water as well as domestic and industrial wastewaters, etc.) and comparable efficiencies were obtained. The proposed USAEME procedure has been demonstrated to be viable, simple, rapid and easy to use for residue analysis of PCBs in water samples.     

Analysis of polychlorinated biphenyls (PCB) by glass capillary gas chromatography

Summary The composition of seven technical PCB-mixtures (Aroclor [Monsanto, USA] und Clophen A [Bayer, FRG]) has been investigated by high-resolution thin-film glass capillary gas chromatography with electron-capture detector. Methylpolysiloxane (SE 30) and purified Apiezon L have been used as liquid phases. Identification of the single PCB components has been performed by comparison of their retention indices with those of polychlorinated biphenyls defined by synthesis or with values calculated from retention index increments. For marking the individual PCB compounds a systematic numbering has been used.Herrn Prof. Dr. R. Bock zum 65. Geburtstag gewidmet     

Solid-phase microextraction of polychlorinated biphenyls

The extraction and analysis of 21 polychlorinated biphenyls (PCBs) ranging from di- to decachlorobiphenyls in ocean, wetland and leachate water samples were achieved using solid-phase microextraction (SPME) with a 100-μm poly(dimethylsiloxane) (PDMS) fiber and gas chromatography–electron-capture detection (GC–ECD). Severe carryover between samples (e.g., 20%) occurs on both stir bars and the SPME fibers demonstrating that it is important to use a new stir bar for each sample, as well as to perform SPME–GC blanks between samples to avoid quantitative errors. The equilibrium partitioning coefficients of individual PCB congeners between PDMS and water were found to be surprisingly different compared to their octanol–water partitioning coefficient (K_ow), demonstrating that K_ow cannot be used to estimate the partitioning behavior of PCBs in the SPME process. Using a 15-min SPME extraction, SPME analysis with GC–ECD was linear (r²≥0.97) from 5 pg/ml to the solubility limit of each congener. Concentrations in water samples obtained by 15-min SPME extractions compared favorably with those obtained by toluene extractions, demonstrating that SPME combined with GC is a useful technique for the rapid determination of PCBs in water samples.     

Radiation degradation of polychlorinated biphenyls

Gradual dechlorination of the polychlorinated biphenyls (PCBs) in alkaline solutions in 2-propanol under the effect of high energy electrons (4.5 MeV) produced by electron accelerator has been studied using a flow-through apparatus of the volume of about 50 L. The dependence of both relative radiation chemical yield and the dechlorination degree on the initial concentration of OH⁻ ions or PCBs, absorbed dose as well as on dose rate has been investigated.     

大流量采样高分辨气相色谱/高分辨质谱法测定大气中的多氯联苯和多溴联苯醚

建立了大流量空气采样高分辨气相色谱/高分辨质谱(HRGC/HRMS)同时分析测定大气样品中多氯联苯(PCBs)和多溴联苯醚(PBDEs)的分析方法。结果表明在采样过程中污染物没有发生穿透。通过添加 13C同位素标准物质进行评价,PCBs和PBDEs的加标回收率分别为60.7%～121.4%和69.9%～140.4%,均符合美国环保署相关方法的要求。PCBs和PBDEs的方法检出限分别低于0.019 pg/m3和0.189 pg/m3;色谱分离效果良好,可以满足大气样品中PCBs和PBDEs的监测需要。     

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.     

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.     

An improved clean-up strategy for simultaneous analysis of polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), and polychlorinated biphenyls (PCB) in fatty food samples

The study and extension of a simple automated clean-up method for polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) to a broad range of polychlorinated biphenyls (PCB) is described. The isolation of seven PCDD, ten PCDF, and three coplanar PCB (cPCB) is extended to eight monoortho substituted PCB and seven so-called "marker PCB" (Aroclor 1260) for fatty food samples. This enables quantification of 35 compounds - including all congeners with a WHO toxic equivalent factor (TEF)--in a single extraction and single purification step. The chromatographic behaviour of mono-ortho PCB and marker PCB on a variety of adsorbents, including basic alumina, has been studied. Partitioning of analytes through multi-column sequences is described and correlated with their structural and electronic properties, by use of molecular modelling calculations. The fractionation process available with the Power-Prep automated clean-up system enables rapid independent analysis of the different groups of compounds. Gas chromatography with high resolution mass spectrometry (GC-HRMS) is used for the PCDD/F and cPCB fraction and quadrupole ion-storage tandem in time mass spectrometry (GC-QISTMS) for analysis of the remaining PCB. A comparison study was performed on quality-control samples and real fatty food samples to evaluate the robustness of the new strategy compared with a reference method. On the basis of this simultaneous clean-up, a rapid simplified strategy for PCDD/F and selected PCB analysis determination is proposed for fatty food samples.     

Novel catalysts for dechlorination of polychlorinated biphenyls (PCBs) and other chlorinated aromatics

Diiron complexes of fluorene and fluorene* (1,2,3,4,5,6,7,8,9-nonamethylfluorene) have been found to be catalysts for the dechlorination of chlorinated aromatics, such as PCBs.     

同位素稀释气相色谱-三重四极杆质谱法测定环境空气中的多氯萘北大核心CSCD

环境空气中的多氯萘(PCNs)一般为痕量水平(pg/m^(3)),要实现其准确定量必然对分析方法的提取、净化和仪器分析提出较高要求。研究通过考察提取溶剂种类、净化流程和色谱-质谱参数,建立了加速溶剂萃取(ASE)-多层硅胶复合中性氧化铝柱的净化方法,并利用同位素稀释气相色谱-三重四极杆质谱(GC-MS/MS)对环境空气中的多氯萘进行测定。同时,通过在采样、提取和进样分析前分别添加同位素内标,开展质量控制和保证。结果表明,在2~100 ng/mL范围内3~8氯萘的平均相对响应因子(RRF)的相对标准偏差(RSD)均小于16%。PCNs同类物的方法检出限为1~3 pg/m^(3)(以样品体积为288 m^(3)计算)。采用基质加标法评价了方法对环境空气样品中PCNs测定的精密度和准确度,低、中、高加标水平下3~8氯萘的平均加标回收率分别为89.0%~119.4%、98.6%~122.5%和93.7%~124.5%,测定结果的平均相对标准偏差分别为1.9%~7.0%、1.6%~6.6%和1.0%~4.8%。整个分析过程中,采样内标和提取内标的平均回收率分别为136.2%~146.0%和42.4%~78.1%,RSD分别为5.6%~7.5%和2.7%~17.5%,满足痕量分析的要求且平行性较好。方法的灵敏度和准确度高,精密度良好,适用于环境空气中3~8氯萘的准确定量测定,可在一定程度上缓解多氯萘监测对高分辨气相色谱-高分辨质谱的依赖,为实现多氯萘的国际履约提供方法支持。