Fast clean-up for polychlorinated dibenzo-p-dioxins, dibenzofurans and coplanar polychlorinated biphenyls analysis of high-fat-content biological samples

A fast clean-up procedure for the low level analysis of polychlorinated dibenzo-p-dioxins. polychlorinated dibenzofurans and coplanar polychlorinated biphenyls in highly fatty biological matrices using high capacity disposable multi-layer silica columns is presented. Results were compared with gel permeation chromatography for removal of lipids. Analytical criteria such as recovery rates, repeatability, reproducibility and robustness are evaluated through a broad range of biological matrices and reference materials analysis. The final proposed procedure for the complete analysis, including pressurized liquid extraction, Power-Prep system clean-up and GC-high-resolution MS analysis requires only 48 h, and allows the simultaneous preparation of up to 10 samples.     

母乳中多种含卤持久性有机污染物的联合检测方法

建立了母乳中多种含卤持久性有机污染物(POPs)的联合检测方法,目标化合物主要包括六溴环十二烷(HBCDs)、多溴联苯醚(PBDEs)、多氯联苯(PCBs)和有机氯农药(OCPs)等.样品的前处理采用液液萃取、凝胶渗透色谱(GPC)净化和固相萃取(SPE)等技术,目标化合物经气相色谱-质谱联用仪(GC-MS)、液相色谱-三重四极杆串联质谱联用仪(LC-MS/MS)和气相色谱-三重四极杆串联质谱联用仪(GC-MS/MS)等进行检测.样品通过GPC除去脂肪,然后经SPE柱进一步净化并进行多组分分离,极大程度地减小了生物样品中复杂基质的干扰,适合样品量相对较小的人体样本中多种超痕量POPs的分析.应用灵敏度高、选择性更好的GC-MS/MS对样品中的PCBs和OCPs等进行分析,进一步降低基质的干扰.方法经过小牛血清加标实验验证,稳定可靠.POPs的加标回收率分别为88.7％～98.8％(PBDEs), 88.5％～92.5％(HBCDs), 67.9％～82.3％(PCBs)和81.7％～116.1％(OCPs),方法检出限分别为0.13～1.8 pg/mL(PBDEs), 0.31～1.2 pg/mL(HBCDs), 0.22～1.4 pg/mL(PCBs)和0.20～1.5 pg/mL(OCPs).采用本方法对潍坊地区20例母乳样品进行分析,结果显示,潍坊市母乳中HBCDs, PBDEs, PCBs、HCHs和DDTs的中值浓度分别为2.86, 7.76, 8.84、140和503 ng/g 脂重,此浓度水平与国内其它地区人群相当.     

Determination of polychlorinated biphenyls in sediment by on-line narrow-bore column liquid chromatography/capillary gas chromatography

Narrow-bore column liquid chromatography coupled on-line with capillary gas chromatography (LC/GC) is used for the determination of polychlorinated biphenyls (PCBs) in sediment via a heart-cutting technique. This method is compared with a method in which two off-line column clean-up steps are used with subsequent analysis by capillary gas chromatography. For the LC/GC analysis the recovery of PCBs was 90–100%. For two sediment samples from the river Meuse the LC/GC and the other, more laborious method showed good agreement.     

High-throughput biomonitoring of dioxins and polychlorinated biphenyls at the sub-picogram level in human serum

We report on the use of a state-of-the-art method for the measurement of selected polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polychlorinated biphenyls in human serum specimens. The sample preparation procedure is based on manual small size solid-phase extraction (SPE) followed by automated clean-up and fractionation using multi-sorbent liquid chromatography columns. SPE cartridges and all clean-up columns are disposable. Samples are processed in batches of 20 units, including one blank control (BC) sample and one quality control (QC) sample. The analytical measurement is performed using gas chromatography coupled to isotope dilution high-resolution mass spectrometry. The sample throughput corresponds to one series of 20 samples per day, from sample reception to data quality cross-check and reporting, once the procedure has been started and series of samples keep being produced. Four analysts are required to ensure proper performances of the procedure. The entire procedure has been validated under International Organization for Standardization (ISO) 17025 criteria and further tested over more than 1500 unknown samples during various epidemiological studies. The method is further discussed in terms of reproducibility, efficiency and long-term stability regarding the 35 target analytes. Data related to quality control and limit of quantification (LOQ) calculations are also presented and discussed.     

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.     

Simultaneous determination of planar chlorobiphenyls and polychlorinated dibenzo-p-dioxins and -furans in Dutch milk using isotope dilution and gas chromatography—high-resolution mass spectrometry

A method is described for the simultaneous determination of planar chlorobiphenyls and dioxins in milk using isotope dilution and gas chromatography—high-resolution mass spectrometry (GC-MS). The method is based on gel permeation chromatography, alumina clean-up and carbon chromatography and is highly automated, making a high sample throughput possible. Data on recovery, accuracy and reproducibility of results obtained with quality control samples are presented. Data for both dioxins and planar chlorbiphenyls from the analysis of samples of Dutch milk from several areas in the Netherlands are also presented. Possible interference of the chlorobiphenyls in the determination of the dioxins in the GC-MS method is discussed.     

Sample pretreatment method for the determination of polychlorinated biphenyls in bird livers using ultrasonic extraction followed by headspace solid-phase microextraction and gas chromatography-mass spectrometry

A simple and reliable sample methodology based on simultaneous ultrasonic extraction, sulfuric acid clean-up and headspace solid-phase microextraction (SPME)-gas chromatography-mass spectrometry has been developed as an advantageous analytical tool for the determination of seven polychlorinated biphenyl congeners in bird livers at low levels. The influence of several parameters on the efficiency of the proposed method was systematically investigated. The clean-up efficiency of sulfuric acid treatment was tested and compared with those of column chromatography (Flosiril, silica gel and alumina) and solid-phase extraction (SPE) (Supelclean ENVI-Carb cartridge) procedures. The use of sulfuric acid in the clean-up step prior to headspace solid-phase microextraction analysis allows the removal of interfering matrix compounds present in the liver extracts that would otherwise cause severe ionization suppression of the polychlorinated biphenyls (PCBs) during the ionization process. The optimized method had good linearity (R2>0.99) over the range studied (5-500 ng/g wet weight) and showed satisfactory level of precision, with RSD values lower than 10.6%. The obtained relative recoveries ranged between 63 and 94%. The limits of detection (0.06-0.63 ng/g wet weight) were low enough to check for harmful levels of polychlorinated biphenyls in biological samples, and were well below most of the restrictive limits established by European Union regulations. The method was found to be reliable under the operational conditions proposed and was applied successfully to the analysis of individual polychlorinated biphenyls in liver tissues. The results obtained from five bird species from Greece revealed the presence of the target compounds in all samples analyzed, at levels ranging between 0.54 and 39.45 ng/g wet weight.     

Multi-residue method for the determination of 57 Persistent Organic Pollutants in human milk and colostrum using a QuEChERS-based extraction procedure

Human breast milk represents the best choice for the nutrition of infants. However, in addition to containing beneficial nutrients and antibodies, it can also be considered the best indicator of infant exposure to contaminants. We developed a multi-residue method using a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure and capillary gas chromatography–triple quadrupole mass spectrometry for the determination of 57 persistent organic pollutants, including 23 organochlorine pesticides, 18 polychlorinated biphenyl (PCB) congeners, and 16 polycyclic aromatic hydrocarbons in human milk and colostrum samples. We have used primary secondary amine in the clean-up step as it gave a more efficient separation of the analytes from fat and superior removal of the co-extracted substances compared with gel permeation chromatography. No significant matrix effect was observed for the tested pollutants, and therefore matrix-matched calibration was not necessary. The average recoveries from spiked samples were in the range of 74.8–113.0 %. The precision was satisfactory, with relative standard deviations below 16 %, while values of 0.1–0.4 μg L^?1 were established as the limit of quantification for all the target analytes (0.05 and 100 μg L^?1). The method was successfully applied to the analysis of 18 human colostrum and 23 mature milk samples. All the samples tested were positive for at least nine different residues, with some samples containing up to 24 contaminants. Remarkably, the contaminants hexachlorobenzene, p,p’-DDE, PCB 138, PCB 180, phenanthrene, fluoranthene, and pyrene were present in 100 % of the colostrum and mature milk samples analyzed.     

Method development for the analysis of polybrominated diphenyl ethers, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzo-furans in single extract of sediment samples

A comprehensive method was developed for quantitative analysis of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) in one single extract of environmental samples. The sample preparation procedure included two fractionation steps using silver nitrate silica chromatography to separate PBDEs from PCBs and PCDD/Fs and florisil column to separate PCBs from PCDD/Fs. Acidic silica, acidic alumina and gel permeation chromatography (GPC, for PCBs) or activated carbon column (for PCDD/Fs) were used for further clean-up. The sample extracts were analyzed by using high-resolution gas chromatography/high-resolution mass spectrometry. The entire method was validated from the analysis of mixed standards of PBDEs, PCBs and PCDD/Fs (n = 3); the analysis of certified reference biota (WMF-01). The method was applied for the analysis of 10 sediment samples collected from Haihe River and Dagu Drainage River in Tianjin City. No significant PBDEs pollution was found in the areas.     

Micropore-free surface-activated carbon for the analysis of polychlorinated dibenzo-p-dioxins-dibenzofurans and non-ortho-substituted polychlorinated biphenyls in environmental samples

2,3,7,8-Substituted polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs) and non-ortho-substituted polychlorinated biphenyls (PCBs) account for almost all of the total toxic equivalents (TEQ) in environmental samples. Activated carbon columns are used to fractionate the samples for GC-MS analysis or bioassay. Micropore-free surface-activated carbon is highly selective for PCDD/Fs and non-ortho-PCBs and can improve the conventional activated carbon column clean-up. Along with sulfuric acid-coated diatomaceous earth columns, micropore-free surface-activated carbon provides a rapid, robust, and high-throughput sample preparation method for PCDD/Fs and non-ortho-PCBs analysis.     

Advances in the gas chromatographic determination of persistent organic pollutants in the aquatic environment

Environmental chemists have been challenged for over 30 years to analyse complex mixtures of halogenated organic pollutants like polychlorinated biphenyls (PCBs), polychlorinated alkanes (PCAs), polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and polychlorinated furans (PCDD/Fs). Gas chromatography (GC) often proved to be the method of choice because of its high resolution. The recent developments in the field of comprehensive two-dimensional GC (GCxGC) show that this technique can provide much more information than conventional (single-column) GC. Large volume injection (e.g. by programmed temperature vaporiser, or on-column injection) can be employed for the injection of tens of microliters of sample extract, in that way substantially improving the detection limits. Electron-capture detection (ECD) is a sensitive detection method but unambiguous identification is not possible and misidentification easily occurs. Mass spectrometric (MS) detection substantially improves the identification and the better the resolution (as with MS/MS, time-of-flight (TOF) MS and high-resolution (HR)MS), the lower the chances of misidentification are. Unfortunately, this comes only with substantially higher investments and maintenance costs. Co-extracted lipids, sulphur and other interferences can disturb the GC separation and detection leading to unreliable results. Extraction, and more so, sample clean-up and fractionation, are crucial steps prior to the GC analysis of these pollutants. Recent developments in sample extraction and clean-up show that selective pressurised liquid extraction (PLE) is an effective and efficient extraction and clean-up technique that enables processing of multiple samples in less than 1h. Quality assurance tools such as interlaboratory studies and reference materials are very well established for PCDD/Fs and PCBs but the improvement of that infrastructure is needed for brominated flame retardants, PCAs and toxaphene.     

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.     

Analysis of polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls in vegetable oil samples by gas chromatography-ion trap tandem mass spectrometry

Gas chromatography coupled to ion trap tandem mass spectrometry (CG-MS-MS) has been evaluated for the analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in vegetable oil samples containing different concentration levels (0.2-6 pg WHO-TEQ g(-1) for both PCDD/Fs and dl-PCBs) of the 29 toxic congeners of PCDD/F and dioxin-like PCBs. The effect of potential interfering compounds such as polychlorinated naphthalenes (PCNs), polychlorinated biphenyls (PCBs) and polychlorinated diphenylethers (PCDEs) on the quantification of mono-ortho PCBs has been investigated. In addition, the influence of the clean-up procedure on the final determination by CG-MS-MS was studied, showing that the quality of the results depends to a great extent on this analytical step. Quality parameters have been established and good precisions (CV: 3-19%) and low limits of detection for PCDD/Fs (0.04-0.20 pg g(-1) oil) and dl-PCBs (0.08-0.64 pg g(-1) oil) were obtained. The method was validated by a comparison of the CG-MS-MS results with those obtained by GC-HRMS.     

Supercritical fluid extraction and clean-up of organochlorine pesticides and polychlorinated biphenyls in mussels

The simultaneous extraction and clean-up of mussel samples followed by gas chromatography with electron-capture detection and mass spectrometric confirmation of 15 organochlorine pesticides (OCPs) and 11 polychlorinated biphenyls (PCBs) is developed using Florisil sorbent in the supercritical fluid extraction cell. The method detection limits vary from 1 to 10 ng/g for OCPs and from 2 to 15 ng/g for PCBs. Mean reproducibilities of 11% and 10% and mean recoveries of 80% and 53%, respectively, for OCPs and PCBs are obtained. The feasibility of the proposed supercritical fluid extraction method was confirmed by analyzing a certified reference material and mussels collected from Taiwan region. The method is simple, rapid and requires only small amounts of samples and solvents. It may serve as a screening protocol for the determination of OCPs and PCBs in mussels on a routine basis.     

Multi-class, multi-residue liquid chromatography/tandem mass spectrometry screening and confirmation methods for drug residues in milk

This paper describes the development and optimization of a multi-residue veterinary drug screening method for whole milk. The drug residues of regulatory interest in milk include beta-lactams, sulfonamides, tetracyclines, fluoroquinolones, and macrolides. Milk samples were extracted with acetonitrile and the samples were then subjected to a clean-up procedure using a bonded solid-phase extraction cartridge and a molecular weight cut-off filter. Liquid chromatography/tandem mass spectrometry (LC/MS/MS) triple quadrupole electrospray methods were developed to monitor for the drugs in milk. Since established tolerance levels are set for most of these drugs in milk, the initial screening procedure was semi-quantitative, where samples were compared to the response of a positive control. The positive control, consisting of an extract from a portion of milk fortified with the drugs at half their allowed levels, was used to set the laboratory's minimum response criteria for unknown samples. Confirmatory analyses, with additional ion transitions for each residue, were performed on the same extracts.     

New strategy for comprehensive analysis of polybrominated diphenyl ethers,polychlorinated dibenzo-p-dioxins,polychlorinated dibenzofurans and polychlorinated biphenyls by gas chromatography coupled with mass spectrometry

A strategy for determination of polybrominated diphenyl ethers, polychlorinated dibenzodioxins, polychlorinated dibenzofurans and polychlorinated biphenyls on fatty matrices has been established. After extraction, the proposed method allows the purification and the fractionation of all target groups of compounds in a simple multi-step automated clean-up. Furthermore, their subsequent analysis is carried out using a single benchtop mass spectrometer, in four separate injections. Required sensitivity considering levels found in the environment is attained using electron impact ionisation followed by tandem in time mass spectrometry. The whole method has been evaluated on standard solution and quality control samples consisting of fortified beef fat. Sensitivity, selectivity, accuracy and repeatability were tested with satisfactory results.     

Multiresidue method for the gas-chromatographic analysis of some polychlorinated and polybrominated pollutants in biological samples

Summary A multiresidue method for the analysis of a number of chlorinated and brominated organic compounds in biological samples has been developed. The method includes gas-chromatographic analysis of hexachlorinated and hexabrominated benzenes (HCB and HBB), polychlorinated and polybrominated biphenyls (PCB and PBB), polychlorinated phenols (PCP), guaiacols (PCG), paraffins (CP) and naphthalenes (PCN), polybrominated diphenyl ethers (PBDE) and the pesticides DDT, polychlorinated terpenes (PCC or toxaphene), chlordanes, hexachlorocyclohexanes (HCH), aldrin and dieldrin. The use of charcoal column in the clean-up procedure makes it also possible to analyze the planar PCB congeners (pPCB). Cod muscle samples were spiked with 10 and 50 times the detection levels of the compounds to be analyzed. The mean recoveries, relative to internal standards, for 40 compounds or compound groups were between 51 and 120%.     

牛奶样品中新霉素残留量的离子色谱法测定

建立了阴离子交换色谱-脉冲安培检测分析牛奶中新霉素残留量的方法.实验采用三氯乙酸沉淀蛋白,弱阳离子交换固相萃取柱富集净化,处理牛奶样品,并考察了三氯乙酸浓度、样品过柱速度以及洗脱剂浓度等因素对牛奶中新霉素测定结果的影响.牛奶中新霉素的回收率在50.3%～76.9%范围内,基底加标工作曲线的相关系数为0.9949(n=6),线性范围为10.0～160.0ng/mL.所建立的方法可满足牛奶中低新霉素残留量的检测需要.     

Rapid and simple determination of aflatoxin M1 in milk in the low parts per 10(12) range

A method for extracting aflatoxin M1 from milk is proposed in which the use of disposable Extrelut clean-up columns simplifies the analysis considerably in comparison with existing methods. The quantitative determination is based on one-dimensional thin-layer chromatography and fluorescence densitometric measurement. The detection limit is 5 ppt (parts per 10(12)) in milk and the recovery is 78 +/- 4% at a level of 50 ppt.     

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.