Comparison of sulfuric acid treatment and multi-layer silica gel column chromatography in cleanup methods for determination of PCDDs,PCDFs and dioxin-like PCBs in foods

Two typical cleanup methods, sulfuric acid treatment and multi-layer silica gel column chromatography, for the determination of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) in seventeen food samples were examined and compared. Vegetables, fruits, cereals, fish, meat and dairy foods were extracted by conventional methods (shaking with acetone/n-hexane or with n-hexane after alkaline treatment). The extracts were cleaned up by sulfuric acid treatment or multi-layer silica gel column chromatography, followed by several column chromatographic steps. Of the samples treated, the vegetable, fruit and cereal samples could be directly applied to the multi-layer silica gel column after extraction. However, the samples containing fats and oils such as fish, meat and dairy foods needed to be treated several times with concentrated sulfuric acid before multi-layer column chromatography, because these samples plugged the column with oily residues. Both cleanup methods gave similar values of isomeric concentrations and showed similar efficiency of purification, and the recoveries ranged from 40 to 120%. These results are considered to provide useful data for the efficient analysis of dioxins in foods which have wide-ranging compositions.     

Modification of cleanup methods for dioxin analysis in green leafy vegetables and comparison of packing methods for a multi-layer silica gel column

To determine polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs) in green leafy vegetables, the cleanup method was modified, and packing methods for a multi-layer silica gel column were compared in food samples. First, the additional cleanup was examined for a mono-ortho PCBs fraction obtained by alumina column chromatography from spinach extract. Small solids such as rough crystals that remained after concentration of the mono-ortho PCBs fraction were identified as long-chain hydrocarbons from leaf epicuticular wax by GC/MS. Cleanup using an activated carbon silica gel column with n-hexane as the washing solvent was effective. Next, multi-layer silica gel columns packed by wet packing and dry packing were compared using komatsuna, salmon and butter as samples. The columns prepared by both methods gave similar values at each isomeric concentration level and showed similar efficiency with favorable recoveries.     

Dietary exposure to dioxins and dioxin-like PCBs of Hong Kong adults: results of the first Hong Kong Total Diet Study

Dioxins and dioxin-like polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) covered by the Stockholm Convention on POPs. To assess the associated health risk of the Hong Kong population, the dietary exposure of the Hong Kong population and various age–gender subgroups to dioxins and dioxin-like PCBs was estimated in the first Hong Kong Total Diet Study (TDS), where food samples were collected and prepared “as consumed”. A total of 142 composite food samples, mainly foods of animal origin and their products and oily food, were analysed for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxin-like PCBs by the high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS) system. Dietary exposures were estimated by combining the analytical results with the food consumption data of Hong Kong adults. The mean and 95th percentile exposures to dioxins and dioxin-like PCBs of the Hong Kong population were 21.9 and 59.7 pg toxic equivalent (TEQ) kg^?1 body weight (bw) month^?1 respectively, which amounted to 31.3% and 85.2% of the provisional tolerable monthly intake (PTMI). The main dietary source of dioxins and dioxin-like PCBs was “Fish and seafood and their products” (61.9% of the total exposure), followed by “Meat, poultry and game and their products” (20.0%) and “Mixed dishes” (6.95%). The study findings suggest that the Hong Kong population is unlikely to experience the major undesirable health effects of dioxins and dioxin-like PCBs.     

Dietary intake of polychlorinated dioxins, furans and dioxin-like polychlorinated biphenyls from foods of animal origin in China

Four food groups of animal origin from the Chinese Total Diet Study (TDS) in 2000 were analysed for 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and 12 dioxin-like polychlorinated biphenyls (PCBs). The samples were from four regions, covering 12 provinces of China. PCDD/Fs, expressed as WHO toxic equivalents (TEQ), ranged from 0.02 to 0.28 pg TEQ g^-1 and dioxin-like PCBs ranged from 0.01 to 0.24 pg TEQ g^-1 (wet weight, ND = LOD), in all samples. Using food consumption data from a 3-day household dietary survey, daily dietary intake of dioxin-like compounds from foods of animal origin in China was estimated. Daily intake among regions ranged 0.09-0.59 pg TEQ kg^-1 body eight day^-1.     

Surveillance of dioxins and polychlorinated biphenyls (PCBs) in food commercialized in Barcelona,Spain

This study explored the potential use of seven congeners of polychlorinated biphenyls (PCBs-7) as indicator compounds for the presence of dioxins and PCBs in food samples, as part of the routine surveillance programme of a public health agency. Samples of 24 foodstuffs with high fat content were collected (ten fresh fish, six dairy products, five meat and three eggs). Duplicate analyses were performed. A research laboratory tested samples for seven polychlorinated dibenzo-p-dioxin (PCDDs), ten dibenzofurans (PCDFs) and twelve dioxin-like PCBs, with limits of detection in the range of ng kg^?1 (ppt). The public health services official control laboratory tested samples for PCBs-7, with a limit of quantification of 5 µg kg^?1 (ppb). The research laboratory detected the presence of dioxins and dioxin-like PCBs in all samples; fish samples had the highest levels (0.04–10.3 pg WHO-TEQ g^?1). The public health service official control laboratory detected PCBs-7 only in five samples, which were all fish. Comparing the results in the two laboratories there seems to be an association between the detection of PCB-7 and the presence of higher levels of PCDD/Fs and dioxin-like PCBs. The use of PCB-7 as an indicator compound may be a practical surveillance strategy for those foodstuffs with higher concentrations of dioxin-like congeners.     

二噁英、多氯联苯和氯丙醇的痕量与超痕量检测技术研究

为建立食品中二噁英、多氯联苯和氯丙醇的检测技术并达到国际水平，将稳定性同位素稀释质谱技术应用到中国食品安全和环境分析领域，针对不同目标化合物分别建立了高分辩磁质谱、四极杆低分辩质谱和离子阱串联质谱的标准化检测技术，特别是采用双同位素稀释同时测定4种氯丙醇的技术。通过对EPA1613A／1668A、FDA4084和EPSI／RM／31、AOAC2000．01等国际先进方法用食品（鱼、鱼油、鹿肉、奶粉和猪油）和环境样品（飞灰、土壤和底泥）开展对比筛选和一系列实验室闻协同性验证，确立了二噁英和多氯联苯的稳定性同位素稀释质谱检测方法，建立了用双稳定性同位素进行酱油中单氯取代和双氯取代氯丙醇同时测定的方法，提出了符合国际规范的技术方案，作为国家标准方法待颁布。利用该检测技术在中国首次开展鱼贝类和土壤中污染的二噁英和多氯联苯同系物类型特征指纹库研究和酱油中氯丙醇的大规模调查，获得了中国人群膳食二噁英毒性当量和氯丙醇摄入状况的暴露数据，不仅证明所建立的方法实用、可行，也为我国履行承诺摸清了家底，提供了依据。     

Dietary intakes of polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls in Spain.

Congener-specific analyses of seventeen 2,3,7,8-substituted PCDD/Fs, three non-ortho and 8 mono-ortho dioxin-like polychlorinated biphenyls (PCBs) were performed on 258 Spanish foodstuff samples, mainly of animal origin, for 2000--03. Daily dietary intakes of PCDD/Fs and PCBs, expressed as toxic equivalents (WHO-TEQs), were estimated by combining food consumption data from the Spanish National Institute Statistics survey and concentration levels measured in individual samples, using upper bound determination values (not detectable = limit of detection). The calculated dietary intake of PCDD/Fs for a person weighing 70 kg was 1.35+/-0.11pg WHO-TEQs kg(-1) bw day(-1), and 3.22+/-0.75 pg WHO-TEQs kg(-1) bw day(-1) if dioxin-like PCBs (non- and mono-ortho PCBs) were included, showing the importance of their inclusion in monitoring studies. Both values were within the range of tolerable daily intake (TDI) proposed by the WHO (1-4pg WHO-TEQs kg(-1) bw day(-1)). The current levels are lower than earlier intakes estimates conducted in Spain. Meat and meat products accounted for more than 35% of the intake, followed by milk and milk products (29%), vegetables oils (19%), fish and seafood (11%) and eggs (4%). Dioxin-like PCBs are an important component in the total WHO-TEQs in foodstuffs. This is particularly true for the fish food group, where the total WHO-TEQs is dominated by dioxin-like PCBs (up to 80% of WHO-TEQs in some cases).     

Concentrations of dioxins and dioxin-like PCBs in feed materials in the Netherlands, 2001–11

This study aimed to obtain insights into contamination of feed materials used in the Netherlands with dioxins (polychlorinated dibenzo-p-dioxins and dibenzofurans) and dioxin-like polychlorinated biphenyls (PCBs). Monitoring results from the period 2001–11, covering in total 4938 samples, were statistically analysed and evaluated against the statutory limits set at the beginning or during this period. The percentage of samples exceeding maximum levels set within the European Union for either dioxins or the sum of dioxins and dioxin-like PCBs were below 1% for most feed categories, except for fish meal (4.1%), clay minerals (binders and anti-caking agents) (3.4%), and vegetable oils and byproducts (1.7%). For most feed categories, non-compliance with the action threshold (roughly 33% lower than maximum levels) for either dioxins or dioxin-like PCBs was up to three times higher than non-compliance with the respective maximum levels. Exceedance of action thresholds was just above 1% for animal fat, pre-mixtures and feed materials of plant origin excluding vegetable oils. For the categories fish meal, clay minerals, and vegetable oils and byproducts, the action thresholds were exceeded by 5.0%, 9.8% and 3.0% of the samples, respectively. In general, the percentages of samples that exceeded the action thresholds and maximum levels were lower than those reported for the European Union by the European Food Safety Authority (EFSA). In most of the feed materials, there seems to be a decreasing trend in concentrations of dioxins or dioxin-like PCBs over the years. However, a lowering of the limits of quantification during this period and the low concentrations in most samples precludes drawing strong conclusions.     

The Determination of PCBs in Meat and Sea Food by GC-QqQ-MS/MS

A new method was developed for the determination of 12 polychlorinated biphenyls (PCBs) in meat and sea food by gas chromatography coupled to triple quadrupole mass spectrometry using selected reaction monitoring technique. The method was based on ultrasonic extraction and florisil column cleaning up. Recoveries of the 12 PCBs ranged from 70.4?% to 100.6?% and the relative standard deviations were from 0.5?% to 12.6?%. The limits of detection ranged from 0.006 to 0.009 μg/kg and the limits of quantitation ranged from 0.02 to 0.03 μg/kg. Eight meat and sea food samples were analyzed for the analysis of the polychlorinated biphenyls using the proposed method.     

Biota--sediment accumulation factors for polychlorinated biphenyls, dibenzo-p-dioxins, and dibenzofurans in southern Lake Michigan lake trout (Salvelinus namaycush)

A set of high-quality, age-specific biota-sediment accumulation factors (BSAFs) for polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) have been determined from concentrations measured with high-resolution gas chromatography/high-resolution mass spectrometry, by use of the 13C isotopic dilution technique, in lake trout and surficial (0-2 cm) sediment samples from southern Lake Michigan. BSAFs ranged from <0.1 to 18 for PCBs and from <0.001 to 0.32 for PCDDs and PCDFs detected in the fish. PCBs with zero or one chlorine in an ortho position had smaller BSAFs than other PCBs. PCDDs and PCDFs with chlorines at the 2,3,7,8-positions had larger BSAFs than most other PCDDs and PCDFs. The fidelity of the relative bioaccumulation potential data between independent lake trout samples, within and among age classes, suggests that differences in slight rates of net metabolism in the food chain are important and contribute to the apparent differences in BSAFs, not only for PCDDs and PCDFs but also possibly for some PCBs. A complicating factor for non-ortho- and mono-ortho-PCBs is the uncertain contribution of enhanced affinity for black carbon (and possibly volatility) acting in concert with metabolism to reduce measured BSAFs for lake trout. On the basis of the association between chemicals with apparent slight rates of metabolism and measured dioxin-like toxicity, several PCDFs with similar measured BSAFs but unknown toxicity may be candidates for toxicity testing.     

Levels of dioxins and dioxin-like PCBs in food of animal origin in the Netherlands during the period 2001–2011

ABSTRACT

The aim of this study was to assess levels of dioxins (polychlorinated dibenzo-p-dioxins and dibenzofurans, PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) (DL-PCBs) in food of animal origin produced in the Netherlands, including potential trends in time. Test results from about 2500 samples of animal derived food products (beef, veal, lamb, chicken, pork, deer, milk and eggs), sampled for the National Residue Monitoring Plan from 2001–2011, were evaluated. Most samples were screened with a bioassay and, if suspected, analysed by GC-HRMS. The fraction of samples which were non-compliant with European maximum levels was rather low, being below 1% for most food products, except for lamb. Exceedance of action levels was particularly observed for lamb and beef. To obtain an insight into background levels, a randomly taken part of the samples was directly analysed by GC-HRMS. In general, only minor decreases in mean PCDD/F and DL-PCB concentrations could be observed for the period 2001–2011. This may be due to a plateauing of current background levels but also to factors like the sensitivity of the analytical method.     

Quantitative source identification of dioxin-like PCBs in Yokohama, Japan, by temperature dependence of their atmospheric concentrations

The source and environmental behavior of dioxin-like polychlorinated biphenyls (PCBs) together with other PCBs and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/PCDFs) were evaluated based on analysis of variations in their atmospheric concentrations in Yokohama, Japan. Potential factors responsible for variations in the atmospheric concentrations of the congeners were investigated by principal component analysis and multiple regression analysis of the data. Two major variations were seen: one had strong temperature dependence, while the other had no significant temperature dependence. A possible explanation for this difference is that the former is related to congeners released by volatilization (e.g., volatilization from commercial PCB products and past polluted environments), while the latter is related to congeners emitted from thermal processes. The relative contributions of dioxin-like PCBs released by volatilization and those emitted from thermal processes were estimated based on the temperature dependence of the atmospheric concentrations. The results suggest that both dioxin-like PCBs emitted from thermal processes and those released by volatilization are significant sources of air pollution in this area in terms of the toxic equivalent (TEQ) for dioxin-like PCBs. We demonstrated that the present approach based on variations in atmospheric concentrations can be useful in providing a qualitative as well as quantitative understanding of source information.     

超声波提取-气相色谱法测定海产品中的多氯联苯

本研究探讨了影响超声波提取海产品中多氯联苯的因素,包括提取温度、时间、功率、液料比和层析条件。根据结果选择的优化超声波条件为：温度40℃,超声波功率540W,时间120min,液料比7:1;层析时淋洗液的起始收集体积为10ml,共收集10ml。样品中的多氯联苯用气相色谱法测定。在选定条件下,方法对多氯联苯的回收率在72.66%～91.56% 之间,平均值87.93%。研究还用样品对选定方法进行了验证,结果表明,本研究所建立的方法可行。     

食品中PCDD/Fs和dlPCBs的检测方法研究进展

二恶英化合物是典型的高毒性持久性有机污染物,可在食物链中不断累积,最终引发食品安全问题,严重威胁人类健康。近年来,食品中二恶英类化合物的分析筛选和监测控制等问题一直是人们研究的重点。本文综述了二恶英类化合物的致毒机制和几种用于分析检测二恶英类化合物方法的基本原理和优缺点,以及国内外分析检测的最新研究进展,并对我国开展二恶英分析监测提出了建议和展望。     

Congener-specific analysis of Pcbs in food samples by using GC/MS

A GC/MS method for congener-specific analysis of polychlorinated biphenyls (PCBs) in food samples was evaluated. There was good agreement between total concentration of PCBs in fish samples (n = 16) measured by using the GC/MS method and the conventional GC-ECD method. The total diet study samples (fishery food, meat, egg, milk, and their products) collected from Osaka in 1982-2001 were analyzed by using the GC/MS method to estimate the temporal trend of daily intake of PCBs from food. The estimated daily intake of total PCBs (sum of tri- to heptaCBs) was in the range of 0.7-4.4 microg/person/day, far below the Japanese provisional acceptable daily intake (250 microg/50 kg-person/day). The dominant congener was 2,2',4,4',5,5'-hexachlorobiphenyl (#153), which accounted for 9-15% of total PCB. The ratio of lower chlorinated congeners decreased from the 1980's to post-2000. The results indicate that the PCB congener profile in foods has gradually changed.     

QuEChERS-气相色谱-串联质谱测定牛奶中有机氯农药及多氯联苯的分析

建立快速测定牛奶中有机氯及多氯联苯残留量的气相色谱-串联质谱（gas chromatography-tandem mass spectrometry,GC-MS/MS）分析方法。样品经30%硫酸-甲醇预处理,正己烷提取,QuEChERS净化,GC-MS/MS测定,基质标准曲线定量。结果表明,待测物质在5～200?μg/L范围内线性关系良好,相关系数大于0.99,检出限为0.1～0.3?μg/kg,样品平均加标回收率为85.5%～115.2%,相对标准偏差小于10%（n=6）。该方法简单、准确、高效,可用于牛奶样品中有机氯及多氯联苯残留的快速筛查和定量检测。     

气相色谱-质谱法检测蔬菜中19种多氯联苯

目的:建立同时检测蔬菜中19种多氯联苯(PCBs)的气相色谱-质谱-选择离子监测(GC-MS-SIM)分析方法。方法:将样品经丙酮/正己烷(体积比1:1)索氏提取、浓硫酸及Florisil固相萃取柱(SPE)净化、氮吹浓缩后,用GC-MS测定。结果:各种PCBs得到较好分离。经方法学验证,19种PCBs标准曲线的线性相关系数在0.99859～0.99962之间,方法检出限0.04～0.43μg/kg(S/N=3),目标化合物加标回收率为87.5%～106.8%,相对标准偏差(RSD,n=5)为1.6%～6.7%。结论:该方法灵敏、准确、稳定,能满足蔬菜样品中痕量多氯联苯的测定。     

纸质食品接触材料中七种多氯联苯的气相色谱法测定

采用正己烷匀浆提取,浓硫酸净化,气相色谱电子捕获检测器检测,建立了纸质食品接触材料中七种多氯联苯残留的检测方法。七种多氯联苯检测的线性范围介于0.002~0.200 mg/L之间,加标回收率为81.6%~112.2%,相对标准偏差为2.1%~4.5%,定量限均为0.01 mg/kg。检测了30余份纸质食品接触材料,均未检测出7种多氯联苯。该方法适用于纸质食品接触材料中七种多氯联苯的残留量分析。     

Dioxin concentrations in the edible parts of Japanese common squid and saury

We examined the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) in muscle and gut tissues from Japanese common squid and saury. These body parts are often eaten in Japan, so it is important to measure their dioxin concentrations and evaluate the risks to consumers. The toxic equivalent (TEQ) concentrations in the squid gut samples (1.0 to 14 pg-TEQ/g fresh weight, n=3) were 50-fold larger than those in the muscle tissues (0.020 to 0.22 pg-TEQ/g fresh weight, n = 3) taken from the same samples. By contrast, the TEQ concentrations in the saury gut samples (0.35 to 0.63 pg-TEQ/g fresh weight, n=3) were only 1.1- to 1.7-fold greater than those in the muscle tissues (0.33 to 0.37 pg-TEQ/g fresh weight, n= 3) from the same samples. The TEQ contents in the squid gut tissues ranged from 60 to 990 pg-TEQ/squid, accounting for about 95% of the total dioxin content of the edible parts of the samples. By contrast, the TEQ contents in the saury gut tissues ranged from 4.4 to 12 pg-TEQ/saury, accounting for less than 25% of the total dioxin content of the edible parts of the samples. These tissues showed comparable PCDD/PCDF-congener and dioxin-like PCB-isomer profiles in both species. The results indicate that squid gut tissues occasionally contain high levels of dioxins, and consumption of this foodstuff could potentially significantly increase the dietary intake of dioxins.     

我国大闸蟹中二噁英类持久性有机污染物的暴露水平研究

目的研究我国大闸蟹中二噁英类持久性有机污染物(persistent organic pollutants,POPs)的暴露水平,评估大闸蟹中二噁英类POPs的主要污染来源。方法样品经正己烷和二氯甲烷(1:1,V:V)提取,浓硫酸沉淀脂类杂质后,过复合硅胶柱和碱性氧化铝柱净化分离目标物。采用同位素稀释高分辨气相色谱-高分辨质谱法(isotope dilution high resolution gas chromatograph-high resolution mass spectrometer,isotope dilution HRGC-HRMS)分析大闸蟹及其食物源中二噁英和多氯联苯的含量。结果蟹肉中二噁英类POPs的总毒性当量(toxic equivalent,TEQ)为0.0092～1.65 pg TEQ/g,平均浓度为0.27 pg TEQ/g。蟹黄(蟹膏)中二噁英类POPs的TEQ浓度水平为1.3～15 pg TEQ/g,平均浓度是蟹肉中平均TEQ值的21倍。估算一亩蟹塘中的物料平衡,发现饲料中二噁英类POPs的TEQ值是大闸蟹的0.85倍,玉米、水草和水仅贡献蟹塘中TEQ输入的4.7%,不考虑生物过程,沉积物中TEQ输入是饲料输入的77倍。结论蟹塘中二噁英类POPs的TEQ输入量高于其输出量,其中沉积物是大闸蟹中二噁英类POPs的主要贡献者,定期清理和更换养殖蟹塘中的沉积物可有效减少大闸蟹对二噁英类POPs的暴露。