Intake of polychlorinated biphenyls (PCB) in the total diet

The content of six selected indicator polychlorobiphenyl (PCB) congeners (nos 28, 52, 101, 138, 153, and 180) in 159 samples of total diet obtained from 20 different people has been determined by capillary gas chromatography. The congeners most frequently found were nos 138 and 153. The mean daily intake of the sum of the three congeners 138, 153, and 180 was 2.3 micrograms/person. This value compares favourable with a value calculated from PCB content of selected foods and consumption data.     

Levels of specific polychlorinated biphenyl congeners in fatty foods from five Canadian cities between 1986 and 1988.

A total of 155 fatty food composites from five major Canadian cities were analysed for 36 selected polychlorinated biphenyl (PCB) congeners. Total PCB congener levels of more than 1 ng/g (wet weight) were found in fresh water fish, canned fish, butter, marine fish and cheese, with fresh water fish (18.7 ng/g) containing 5 to 10 times more total PCBs than the other four food commodities. Milk (2%), cooking oils/salads and canned meat soup contained less than 0.1 ng/g (wet weight). The observed total PCB residue levels in fatty foods were well within the Canadian guidelines for fish, dairy products, poultry, eggs and beef. The most predominant congeners found in fish, butter, cheese, meat and poultry were the 2,2',4,4',5-, 2,3',4,4', 5-pentachloro-, 2,2',3,4,4',5'-, 2,2',4,4',5,5'-hexachloro- and 2,2',3,4,4',5,5'-heptachlorobiphenyls. The predominant congener pattern was not always evident in other dairy products (e.g. ice cream) and processed foods (e.g. canned meat soup). An attempt was made to relate the intake of PCB congeners from fatty foods with congener levels found in adipose tissue of Canadians. The estimated daily intake of some specific PCB congeners from fatty foods, in most cases accounted for more than half the total deposit of these congeners in adipose tissue of Canadians.     

辣椒制品中大红粉的筛查及检测

采用自制的微型GPC柱对辣椒制品中的非食用色素进行筛查,筛选到一种未知的脂溶性非食用色素,采用紫外可见光谱法、高效液相色谱法、液相色谱-质谱/质谱法及液相色谱-飞行时间质谱法对该未知色素与市售化工染料大红粉进行比较分析,发现该未知色素为大红粉(Pigment Scarlet Powder).为了有效开展食品中大红粉的检测,建立了一种直接溶剂提取法对辣椒制品中大红粉进行检测的方法,该方法操作简便,可实现对辣椒制品中大红粉的快速检测,并在部分辣椒制品中检出大红粉.     

Changes in enantiomeric fractions during microbial reductive dechlorination of PCB132, PCB149, and araclor 1254 in Lake Hartwell sediment microcosms

The enantioselectivity of microbial reductive dechlorination of chiral PCBs in sediments from Lake Hartwell, SC, was determined by microcosm studies and enantiomer-specific GC analysis. Sediments from two locations in the vicinity of the highest levels of PCB contamination were used as inocula. Dechlorination activity was monitored by concentration decreases in the spiked chiral PCBs and formation of dechlorination products using both achiral and chiral chromatography. Live microcosms spiked with PCB132 (234-236) exhibited dechlorination of PCB132 to PCB91 (236-24) and PCB51 (24-26). Meta dechlorination was the dominant mechanism. Microcosms spiked with PCB149 (245-236) exhibited preferential para dechlorination of PCB149 to PCB95 (236-25), followed by meta dechlorination to PCB53 (25-26) and subsequently PCB19 (26-2). Dechlorination of chiral PCB132 and PCB149 was not enantioselective. In Aroclor 1254-spiked microcosms, reductive dechlorination of PCB149 also was nonenantioselective. These results suggest that dechlorinating enzymes responsible for the dehalogenation of the chiral PCB132 and PCB149 congeners bind the two enantiomers equally. Reductive dechlorination of PCB91 and PCB95, however, occurred in an enantioselective manner, indicating that the dechlorinating enzymes for these PCBs are enantiomer-specific. The chlorine substitution pattern on the biphenyl ring appears to influence whether reductive dechlorination of chiral PCB congeners is enantioselective. Enantioselective PCB dechlorination by the microbial population of Lake Hartwell sediments occurs for select chiral PCBs; thus, certain chiral PCBs might be useful as markers for in situ reductive dechlorination.     

Enantiomeric fraction of selected chiral polychlorinated biphenyls in cow, goat, and ewe milk and dairy products by heart-cut multidimensional gas chromatography: first results

The concentration of the most relevant polychlorinated biphenyl (PCB) congeners has been determined in milk and dairy products (i.e., cheese and yogurt, from cow, goat, and ewe). In addition, the enantiomeric composition of 11 atropisomeric PCB has been determined for the first time in this type of product, using heart-cut multidimensional gas chromatography and 2 enantioselective columns for the unambiguous determination of both enantiomers. Results showed a deviation from the racemic composition for PCB 135, 136, 176, 171, and 183 in the samples analyzed. Whereas PCB 135, 136, and 176 showed an enrichment of the first eluted enantiomer, congeners 171 and 183 showed an enrichment of the first or second eluted enantiomer depending on the dairy product and species. The remaining congeners analyzed (PCB 84, 91, 95, 132, 149, and 174) did not present a clear enrichment of any of the enantiomers. Therefore, differences in the enantiomeric composition of some of the target atropisomeric PCB have been found among the 3 species and among the milk samples and the related dairy products analyzed. Enantioselective species-dependent processes, as well as enantioselective processes carried on by microorganisms during the fermentation and ripening in the latter could be possible explanations for the differences observed. However, changes in the enantiomeric composition are still not well understood, and further investigation in this direction is recommended.     

Determination of residues of organochlorine insecticides and polychlorinated biphenyls in cereals, feeds and water

A semimicro method for the quantitative determination of chloro-organic insecticides (COI) and polychlorinated biphenyls (PCB) in cereals, feed-pellets and water is presented. The extraction of the active compounds is carried out with n-hexane or dichloromethane. The extracts of cereals and pellets are purified by column chromatography with aluminum oxide. A silicagel column is used for the separation of the compounds into COI as well as PCB and hexachlorobenzene. The determination of the active compounds is carried out by gas chromatography using an electron capture detector. Recoveries range between 70 and 108%, except for beta-endosulphan.     

Using extrathermodynamic relationships to model the temperature dependence of Henry's law constants of 209 PCB congeners

Our previous measurements of the temperature dependencies of Henry's law constants of 26 polychlorinated biphenyls (PCBs) showed a well-defined linear relationship between the enthalpy and the entropy of phase change. Within a homologue group, the Henry's law constants converged to a common value at a specific isoequilibrium temperature. We use this relationship to model the temperature dependencies of the Henry's law constants of the remaining PCB congeners. By using experimentally measured Henry's law constants at 11 degrees C for 61 PCB congeners described in this paper combined with the isoequilibrium temperatures from our previous measurements of Henry's law constants of 26 PCB congeners, we have derived an empirical relationship between the enthalpies and the entropies of phase change for these additional PCB congeners. A systematic variation in the enthalpies and entropies of phase change was found to be partially dependent on the chlorine number and substitution patterns on the biphenyl rings, allowing further estimation of the temperature dependence of Henry's law constants for the remaining 122 PCB congeners. The enthalpies of phase change for all 209 PCB congeners ranged between 10 and 169 kJ mol(-1), where the enthalpies of phase change decreased as the number of ortho chlorine substitutions on the biphenyl rings increased within homologue groups. These data are used to predict the temperature dependence of Henry's law constants for all 209 PCB congeners.     

Long-term fate of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in an agricultural soil

Laboratory studies are useful for understanding the behavior of persistent organic pollutants (POPs) in soil, although such investigations do not always relate directly to field conditions. Outdoor lysimeter studies may be used to overcome this problem. This work aimed to investigate the behavior of two polycyclic aromatic hydrocarbons (PAHs) (fluoranthene and benzo[a]pyrene) and two polychlorinated biphenyls (PCBs; congeners 28 and 52) in soil, using lysimeters established in 1990 atthe Agrosphere Institute (Forschungszentrum Julich GmbH, Germany). The two PAHs were in one lysimeter, and the PCBs were in a second lysimeter. Afurther aim of the study was to determine soil half-lives for each of the contaminants. The overall decline in PAH concentrations was considerably greater than forthe PCBs over the 152 month study. The PCBs exhibited greater chemical extractability than the PAHs and were demonstrated to have migrated through the soil column to a greater extent than the PAHs. Loss of PCBs from surface soil was not considered to have been congener specific for the two PCB congeners in this study. The two PAHs varied in their extents of total loss and movement through the soil column. Soil half-lives were determined as 10.9 y for [12C]PCB 28, 11.2 yr for [12C]PCB 52, 2.7 yr for benzoqpyrene, and 32 d (phase 1) to 38 yr (phase 2) for fluoranthene. These are shown to disagree with some previous estimates of POP half-lives in soil, suggesting that previous studies underestimated persistence by 10-fold or more.     

Physiologically based persistent organic pollutant accumulation in pig tissues and their edible safety differences: An in vivo study

As one of the most important animal food sources, pigs are an important model in the assessment of human exposure to persistent organic pollutants (POPs). In the present study, the distribution of the administrated polychlorodibenzo-p-dioxin/furan (PCDD/F)–polychlorinated biphenyl (PCB) mixture and polybrominated diphenyl ethers (PBDEs) in the different tissues of pigs, including liver, lung, kidney, subcutaneous fat, mesentery and muscle, for understanding the physiologically based pollutant accumulation in these tissues and their edible safety was investigated. It was found that liver had a much higher potential to accumulate PCDD/Fs and dioxin-like pollutants like PCB-126 than the other tissues, but it did not specifically concentrate PBDE congeners as compared to the other tissues. The different PCDD/F congeners and PCB-126 followed a similar distribution pattern in the different tissues; also the different PBDE congeners have the similar pattern in these tissues. The liver’s higher concentrating potency for dioxin-like pollutants may result from its detoxification function, however, it can concentrate dioxin-like pollutants but not PBDEs may suggest that it is the toxicity but not lipophilic property of these POPs dominated their accumulation in liver tissues. Also the result suggested that liver is a high-risk edible tissue for dioxin-like pollutants. In conclusion, the present study suggested that physiologically based assessments are necessary for evaluating edible tissue safety in animal source foods.     

Simultaneous Determination of Ten Ginsenosides in American Ginseng Functional Foods and Ginseng Raw Plant Materials by Liquid Chromatography Tandem Mass Spectrometry

A method was established for simultaneous determination of ten ginsenosides (ginsenosides Rg1, Re, Rb1, Rf, Rb3, 20(S)-F1, 20(S)-F2, Rg3, 20(S)-Rh2, and pseudoginsenoside F11) in American ginseng functional foods and ginseng raw plant materials by high-performance liquid chromatography with electrospray ionization tandem mass spectrometry. After samples were ultrasonically extracted with 60 % (v/v) methanol aqueous solution, centrifuged, and filtered, the analytes in sample solution were separated by a Hypersil Gold column (2.1?×?150 mm, 5 μm) at 25 °C with a programmed gradient elution. Mobile phases consisting of 0.01 % (v/v) formic acid aqueous solution and methanol were used for elution with a flow rate of 250 μL/min. Qualitative determination was completed by comparison with characteristic ion pairs and retention time of the targeted compounds using selective reaction monitoring mode. Digoxin was used as internal standard in positive ionization mode. The internal standard curves were used for quantification. The limits of detection of the method were from 1.0 to 5.0 mg/kg. The linear dynamic ranges covered from 10 to 5,000 μg/L (R ²?≥?0.99). Principal component analysis was used for distinguishing ginseng sources of the functional foods. Thirty-seven samples, including 11 American ginseng raw plants, 12 labeled American ginseng functional foods, 5 notoginsengs, 5 Asian ginsengs, and 4 red ginsengs, were analyzed by this method. The results showed that five labeled American ginseng functional foods might have quality defects and six functional foods might be adulterated. This method can be applied to quality control and ginseng source assessment of American ginseng functional foods.     

Congener-specific carbon isotopic analysis of technical PCB and PCN mixtures using two-dimensional gas chromatography-isotope ratio mass spectrometry

Analysis of stable carbon isotope fractionation is a useful method to study the sources and fate of anthropogenic organic contaminants such as polychlorinated biphenyls (PCBs) in the environment. To evaluate the utility of carbon isotopes, determination of isotopic ratios of 13C/12C in source materials, for example, technical PCB preparations, is needed. In this study, we determined delta13C values of 31 chlorobiphenyl (CB) congeners in 18 technical PCB preparations and 15 chloronaphthalene (CN) congeners in 6 polychlorinated naphthalene preparations using two-dimensional gas chromatography-combustion furnace-isotope ratio mass spectrometry (2DGC-C-IRMS). Development of 2DGC-IRMS enabled improved resolution and sensitivity of compound-specific carbon isotope analysis (CSIA) of CB or CN congeners. Delta13C values of PCB congeners ranged from -34.4 (Delors) to -22.0/1000 (Sovol). Analogous PCB preparations with similar chlorine content, but different geographical origin, had different delta13C values. PCB preparations from Eastern European countries--Delors, Sovol, Trichlorodiphenyl, and Chlorofen--had distinct delta13C values. PCB mixtures showed increased 13C depletion with increasing chlorine content. Delta13C values for individual CB congeners varied depending on the degree of chlorination in technical mixtures. Delta13C values of CN congeners in Halowaxes ranged from -26.3 to -21.7/1000 and these values are within the ranges observed for PCBs. This study establishes the range of delta13C values in technical PCB and PCN preparations, which may prove to be useful in the determination of sources of these compounds in the environment. This is the first study to employ 2DGC-IRMS analysis of delta13C values in technical PCB and PCN preparations.     

Microcosm experiments to assess the effects of temperature and microbial activity on polychlorinated biphenyl transport in anaerobic sediment

Increased polychlorinated biphenyl (PCB) loadings from sediment to the water column under low-flow conditions during late spring and summer months have been observed in the Grasse River (Massena, NY) and other PCB-contaminated rivers in the United States. Temperature appears to be an important factor affecting this phenomenon, as increased sediment temperature leads to increased microbial and bioturbator activity as well as increased rates of diffusion and desorption. Laboratory-scale sediment microcosms were developed and used to study with fine-scale resolution the effects of temperature and microbial activity on PCB transport in river sediment. Over the time course of these experiments, with the extraction procedures used, irreversible sorption of each congener to sediment was observed and increased with aging of the sediment. Temperature-dependent transport was observed for PCB congeners 2,4,5-trichlorobiphenyl (BZ29), 2,5-dichlorobiphenyl (BZ9), and 2-chlorobiphenyl (BZ1) in Grasse River sediment and a synthetic sediment system. The fastesttransport of the congeners occurred in biologically active Grasse River sediment followed by biologically inactive (autoclaved) Grasse River sediment, and synthetic sediment. The increased transport in biologically active sediment demonstrated the importance of microbial activity, in particular gas bubble generation, in PCB transport in near-surface sediments.     

Multiresidue analysis of PCB, organochlorine pesticides and chlordanes in marine products by GC-micro ECD

A multiresidue method using dual-injection, dual-column, and dual-micro electron capture detection gas chromatography (dual-column GC-μECD) was developed for the determination of PCB, organochlorine pesticides and chlordanes in marine products. The sample was extracted with hexane-acetone (2 : 1), and the extract was cleaned up by gel permeation chromatography(GPC)/solid-phase extraction (SPE). The GPC fraction was selectively collected, and loaded directly onto a graphitized carbon/PSA 2-layered column. After fractionation by 4% hydrated silica-gel column chromatography, each fraction was determined by dual-column GC-μECD. Recoveries of PCB, organochlorine pesticides and chlordanes were in the ranges of 84-109% (RSD ≤ 21.6%), 74-117% (RSD ≤ 14.6%) and 69-114% (RSD ≤ 12.9%), respectively. This method is superior to single chromatography for the determination of total PCB, and should be useful for monitoring of these pollutants in marine products.     

药食两用类食品中赭曲霉毒素A的高效液相色谱-荧光检测方法

目的:采用免疫亲和净化和高效液相色谱技术,建立淀粉、糖类药食两用食品中赭曲霉毒素A的测定方法。方法:样品粉末经甲醇-水(8:2,V/V)涡旋、超声及振摇提取,提取液以磷酸盐缓冲液稀释后,用商品免疫亲和柱净化,含有赭曲霉毒素A的甲醇洗脱液用高效液相色谱技术分析,C18反相色谱柱分离,荧光检测器测定。结果:赭曲霉毒素A的最低检出浓度为1.0μg/kg(RSN=3);在0.5～100ng/mL范围内,峰面积与质量浓度呈线性关系(r=0.9995);以不含赭曲霉毒素A的太子参、莲子、薏苡、麦冬和龙眼肉为加标基质,加标水平为1～8μg/kg时,平均回收率在81.8%～107%之间,RSD为1.66%～15.0%(n=3)。结论:免疫亲和柱能和高效液相色谱-荧光检测相结合取得较为满意的结果,准确度高、精密度好,满足欧盟对食品饲料中OTA检测方法的要求,适合于淀粉、糖类药食两用食品中赭曲霉毒素A的测定。     

Levels of selected polychlorinated biphenyl congeners in total diet samples from Aragón, Spain.

Six congeners of polychlorinated biphenyls (PCB 28, 52, 101, 138, 153, and 180) were investigated in 281 samples of different meals of the average diet consumed in Aragon, northeast Spain. PCB residues were extracted with organic solvents according to the techniques recommended by the U.S. Food and Drug Administration and the Netherlands' Ministry of Welfare, Health, and Cultural Affairs; the residues were cleaned up by gel permeation chromatography. Quantitation of analytes was carried out by capillary gas-liquid chromatography using electron capture detector. The identity of the peaks was confirmed by mass spectrometry. PCB residues were found only in fish meals (50% positive samples) with a mean level of 96.3 ng/g on a lipid basis. Congeners detected in fish meals were 138, 153, and 180, with mean values of 117.0, 122.3, and 36.2 ng/g on a lipid basis, respectively.     

Determination of polysorbates in foods by solid-phase extraction and high-performance liquid chromatography

A simple and rapid method using refractive index high-performance liquid chromatography (RI-HPLC) was developed for the determination of polysorbates (PS) in processed foods. PS were extracted with ethyl acetate containing 5% methanol. The extract was cleaned up on a multimode cartridge (300 mg) and an Alumina-N cartridge (500 mg) to remove fats and food color. HPLC separation was performed on a C18 column (4.6 i.d. x 150 mm) with methanol as the mobile phase. The recoveries of PS80 from nine kinds of foods fortified at the levels 1-5 g/kg were 80-99%. The limit of quantitation for PS80 in foods was 0.10 g/kg. The proposed method was applied to Worcestershire sauce that was PS-positive by TLC, and PS was confirmed to be present as PS80 at the concentration of 0.13 g/kg.     

Polychlorinated biphenyl residues in foods from a contaminated region of Yugoslavia.

PCB levels in food and the dietary intake of PCBs from food grown in a contaminated region in Bela Krajina (Slovenia, Yugoslavia) are reported. A large variation in the contribution of PCB congeners to total PCB levels in food of animal and leafy vegetable origin was found. Although guidelines for PCB tolerances exist only for food of animal origin, it was estimated that leafy vegetables and unpeeled fruits from the contaminated region present a significant source of human exposure to PCBs. PCB residues in fish and eggs exceeded the tolerances set by the FDA. Utilizing the official statistical data on food consumption, the dietary intake of PCBs from food of animal origin decreased from 1985 to 1988 from 14.5 to 1.6 mg/year per person, respectively, after the use of PCBs ceased in the nearby plant. The dietary intake in 1988 of PCBs from foodstuffs of vegetable origin and fruits was 4.6 mg/year per person. The quantitation of PCBs was made from the sum of 36 individual PCB congeners, obtained by high resolution gas chromatography with an electron capture detector.     

Simultaneous Determination of Seven Adulterants in Slimming Functional Foods by HPLC�CESI�CMS/MS

A high-performance liquid chromatography?Celectrospray ionization?Ctandem mass spectrometric method for simultaneous determination of seven adulterants including pseudoephedrine, norpseudoephedrine, caffeine, strychnine, fenfluramine, sildenafil, and amfepramone in slimming functional foods was established. For tablet formulation, the target chemicals were extracted with ammoniated methanol, while for liquid samples, plant powder, or capsules formulations, these chemicals were extracted with a mixture solution of ammoniated methanol-diethyl ether (2:1 v/v). After anhydrous sodium sulfate being added, the extracts were centrifuged and then the supernatant was evaporated to dryness under condition of a nitrogen gas flow. The residue was reconstituted with acetonitrile?Cwater (1:9 v/v) to produce a test solution. Chromatographic separation was accomplished using a RP-C18 column with a gradient elution procedure using 0.03% formic acid in acetonitrile and 0.01% formic acid solution. Seven chemicals were separated and detected in 10 min. Clenbuterol was used as an internal standard. The recoveries of seven targeted chemicals in different formulations are from 81.2% to 110.3%. Limits of detection of the method are from 4.2 to 16.7 ??g kg^?1 with relative standard deviations of 1.1?C8.4%. The linearity of the method ranges from 2.0 to 500 ng mL^?1 for all chemicals, with linear correlation coefficients varying from 0.9982 to 0.9992. The method has been used for determining the target chemicals in nine slimming functional foods, and satisfactory results are achieved. Among these tested samples, norpseudoephedrine and fenfluramine were not detected for all samples. Some other components, such as pseudoephedrine, amfepramone, strychnine, and sildenafil were detected in one or more samples, while caffeine was detected in almost all of these tested samples.     

烹调食品中杂环胺检测的样品前处理方法研究

杂环胺作为一类在烹调过程中产生的强致癌,高突变活力的物质,越来越受到科研工作者的关注。本文主要对食品中杂环胺检测的前处理技术进行了综述,介绍了从不同样品基质中进行提取和预浓缩的分析策略,如常用的液液萃取,液固萃取,固相萃取,在线串联液液萃取和固相萃取等前处理方法,重点讨论了在样品处理过程中的吸附剂和溶剂选择的问题,讨论了分析技术所需要的条件和最能达到准确结果的方法。