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1.
Herring ( Clupea harengus) (as well as sprat and mackerel) is a fish species intensively harvested by the Polish fishing fleet. Its relatively low price and the habits of Polish consumers contribute to its high economic importance in Poland. Among 125.6 thousand tons of marine fish harvested in 2006, herring constituted 22.2 thousand tons (including 7.6 thousand tons harvested from the North Sea). Fish are usually subjected to various culinary treatments, which can influence the concentrations of contaminants in final products. Therefore, the present study aimed at determining the effect of three non- ortho-polychlorinated biphenyl (PCB) congeners (PCB 77, PCB 126, and PCB 169) and three mono- ortho-PCB congeners (PCB 114, PCB 156, and PCB 157) in the tissues of herring slices. Concentrations of dry matter and lipids in the final product were increased by 15.9 and 20.5%, respectively. Brining, which preceded the process of smoking, did not significantly influence concentrations of PCB congeners in herring slices. However, smoking resulted in significant ( p < 0.05) changes in concentrations of three non- -ortho PCBs. The biggest dynamics of losses in relation to smoking duration was observed for PCB 77 (30.2%). For PCB 126, the biggest losses occurred after 1 h of drying, followed by slight changes after 1.5 and 2 h of proper smoking and another increase of losses in the final product after 2.5 h. The duration of smoking did not significantly influence PCB concentrations in wet weigh, as their losses in lipids were much bigger. The observation is derived from strong negative correlations between concentrations of the congeners in lipids and lipid concentrations in herring slices during hot smoking ( r ranging from -0.824 to -0.950). Although the lipid concentration in the smoked fish increased, the PCB content diminished. It shows that during drying of the fish slices, PCBs codistilled with water vapor, settling on the walls of the smoking chamber and smoking trolleys. During the proper smoking, the compounds released with the smoke back to the smoking chamber and settled on the surface of smoked fish together with the disperse phase of the smoke (aerosol). Hot smoking contributed to a reduction of toxic equivalents (TEQs) by 22.7% (converted into lipids 41.9%), and in the final product, it amounted to 0.0188 +/- 0.0023 ng TEQ/kg of wet weight (0.0977 +/- 0.0064 ng TEQ/kg of lipids). The reduction was significantly higher than resulting from hot smoking of mackerel slices, when TEQs were reduced by 17.9% wet weight (converted into lipids 31.7%).  相似文献   

2.
A surveillance program on polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) in 29 foodstuff samples produced all over the four provinces in Catalonia (Spain) is presented. The study included the analyses of milk, egg, meat (beef, chicken, and pork), mussel, and olive oil samples. A previously developed method for the simultaneous analysis of the 2,3,7,8-substituted PCDDs/PCDFs and the dioxin-like PCBs, as well as the indicator PCBs, was employed. Total toxicity equivalent (TEQ) values were calculated using the toxicity equivalent factors (TEFs) proposed by the World Health Organization (WHO) for dioxin-like PCBs, PCDDs, and PCDFs. The TEQ(PCDD/F) levels were below the limits proposed in the draft of the EC regulation for food commercialization in the European countries. These limits are the following: 2 pg WHO-TEQ/g fat for pork, 3 pg WHO-TEQ/g fat for milk and chicken, 5 pg WHO-TEQ/g fat for egg and beef, and 3 pg WHO-TEQ/g whole product for fish. The contributions of PCDDs/Fs and dioxin-like PCBs in the total toxicity of the samples were calculated for each matrix. The results showed that the TEQ(PCB) contribution varied from 27% in olive oil samples to 81% in mussel samples. These findings suggest that the regulation of TEQ contents in food should include not only the TEQ(PCDD/F), but also the TEQ(PCB).  相似文献   

3.
The United States Environmental Protection Agency (USEPA) has completed a survey of dioxin-like compounds (including 17 dioxin and furan (CDD/F) congeners and 12 coplanar polychlorinated biphenyl (PCBs) congeners) in dairy feeds from 10 dairy research facilities around the United States, sampling the overall mixtures and the major and minor feed components. Low levels of dioxin were found in all feed mixtures with an average concentration of 0.05 pg/g (ppt) toxic equivalent (TEQ) dry weight. This is lower than previously found in dairy feeds by about a factor of 4. While it is possible that generally lower levels of dioxins in the environment in recent years may explain this result, examinations of the data suggest that the oven drying used to prepare the wet feed samples could have resulted in a loss of dioxins from the feed materials. The percentage of the total TEQ due to CDD/Fs was about four times that of PCBs. Leafy vegetations in the feed (the silages and the hays) had concentrations about twice as high as nonleafy, protected vegetation of the feeds (the ground or meal corn, cottonseed, and others). Minor components did not significantly influence the final feed mixture concentration of dioxin TEQ. However, in one of the feed mixtures, a minor component with a high concentration of 38.5 ppt TEQ effectively doubled the concentration of the overall feed mixture.  相似文献   

4.
Concentrations of four naturally produced halogenated dimethyl bipyrroles (HDBPs) were quantitated in marine fish (n = 10), freshwater fish (n = 10), canned fish (n = 10), and shrimp composites (n = 10) collected from 1992 to 2002 for the Canadian Total Diet Study. Canned fish composites composed of epipelagic higher trophic level species contained the highest concentration of HDBPs (SigmaHDBP geometric mean +/- standard error = 880 +/- 690 pg/g of wet weight, n = 10), which was significantly higher than that found in the other three composites. There were no significant temporal trends of HDBP concentrations observed for any of the four composites. The estimated daily intake of HDBPs via consumption of fish and seafood was determined to be 53 pg/kg of body mass/day and 0.10 pg of TEQ/kg of body mass/day when transformed to 2,3,7,8-tetrachlorodibenzodioxin equivalents (TEQs). In the canned fish and shrimp composites collected in 1998, HDBPs accounted for approximately 98 and 19%, respectively, of the total quantitated TEQ (which included polychlorinated biphenyls, dioxins, and furans). The results of this study provide the first estimate of human exposure to naturally produced bioaccumulating organohalogens.  相似文献   

5.
We investigated the cooking-induced changes in concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) (dioxins) using mackerel and beef. The concentrations of dioxins (29 congeners) were determined by isomer specific analyses and were compared between uncooked and cooked samples. The cooking procedures examined in this study included grilling as a fillet, boiling as a fillet, and boiling as tsumire (small, hand-rolled balls) for mackerel and boiling as a slice, broiling as a slice, and broiling as a hamburger for beef. Three trials were carried out for each cooking method. Generally, concentrations of dioxins were reduced in every cooking trial. When nondetected congener concentrations were assumed to be half the limit of detection for mackerel, the maximum percentage reductions of total concentrations given as 2,3,7,8-tetraCDD equivalents (TEQ) were 31% in grilling as a slice, 14% in boiling as a slice, and 21% in boiling as tsumire under the conditions of this study. In contrast, for beef, the reductions were 42% in boiling as a slice, 42% in broiling as a slice, and 44% in broiling as a hamburger. These results suggest that ordinary cooking processes with heating undoubtedly reduce the dioxin content in animal products, and the reductions estimated should be considered when dioxin intake is evaluated using contamination data for individual food items.  相似文献   

6.
The polychlorinated dibenzo-p-dioxin (PCDD), dibenzofuran (PCDF), and polychlorinated biphenyl (PCB) contents of 123 Spanish commercial salmon, tuna fish, sardine, oyster, mussel, and clam samples from 1995 to 2003 were investigated. A significant decrease of dioxin and non-ortho PCB concentrations in the studied species was found over the years. The decrease was greater in the case of dioxins than in that of non-ortho PCBs, especially during the early years of the study. PCB and PCDD/F concentrations in the years 2001-2003 were comparable to those reported in the literature for similar species collected after 1999. Mean PCB concentrations ranged from 3.46 ng/g of fresh weight (fw) in clams to 100 ng/g of fw in tuna fish. PCDD/F mean current levels ranged from 0.62 pg/g of fw in clams to 2.89 pg/g of fw in oysters. Toxic equivalent quantities (WHO-TEQ) ranged from 0.05 pg of WHO-TEQ(PCDD/Fs)/g of fw in clams to 0.5 pg of WHO-TEQ(PCDD/Fs)/g of fw in salmon (in the upper bound determination levels). When coplanar PCBs were included, the WHO-TEQ(PCDD/Fs+cop) (PCBs) values increased by a range of 1.7 times in oysters to 14.1 times in tuna fish. The decrease in dioxin concentrations suggests that efforts to control dioxin emissions and to reduce human exposure through foodstuffs are succeeding. The high contribution of PCBs to total WHO-TEQs in the fish and shellfish species investigated suggests that it is important to determine PCBs in foodstuffs, and especially in fish products, and they should be included in further research and future legislation.  相似文献   

7.
Methods to remove dioxins and polychlorinated biphenyls (PCBs) from fishmeal were investigated and compared. The tested methods include (i) lowering the fat content and simultaneously the level of toxic contaminants using either organic solvents or (ii) lowering the fat content using protease and (iii) removal of dioxins and PCBs using either oil extraction or (iv) breakdown of dioxin and PCBs using oxidoreductase. The results showed that the organic solvents tested (ethanol, isopropanol, and isohexane) were efficiently lowering the oil content of the fishmeal by 80%. However, the treated fishmeal has a low fat content and may contain traces of solvent. The protease alcalase was not as efficient as the solvent extraction and only removed approximately 30% of the oil but presented the advantage of being a mild process. Other proteases, alone or in combination with other enzymes, might give better yield if the reaction conditions are optimized. In contrast, extraction of dioxin and PCBs using olive oil or fish oil was very effective and resulted in 60-75% extraction of dioxin and PCBs, respectively, after a single extraction step. No preference for the oil type was observed. This method is very simple and quick and does not require an important investment for the fishmeal producer. It is expected that with optimization this method could be implemented at an industrial scale without too many difficulties. In contrast, the oxidoreductases tested did not result in a major degradation of dioxins and PCBs with only 10-15% degradation achieved. However, with the recent advancement in biotechnology, it is possible that future research will result in the development of enzymes that effectively degrade recalcitrant contaminants.  相似文献   

8.
The fungus Fusarium graminearum, a pathogen of both wheat and maize, produces a toxin, deoxynivalenol (DON), that causes disease in livestock. A rapid test for DON in wheat was developed using the principle of fluorescence polarization (FP) immunoassay. The assay was based on the competition between DON and a novel DON-fluorescein tracer (DON-FL2) for a DON-specific monoclonal antibody in solution. The method, which is a substantial improvement over our previous DON FP immunoassay, combined a rapid (3 min) extraction step with a rapid (2 min) detection step. A series of naturally contaminated wheat and maize samples were analyzed by both FP immunoassay and liquid chromatography (HPLC-UV). For wheat the HPLC-UV and FP methods agreed well (linear regression r(2) = 0.936), but for maize the two methods did not (r (2) = 0.849). We conclude that the FP method is useful for screening wheat, but not maize, for DON.  相似文献   

9.
针对持久性有机污染物在水生生物体内易于积累的特性,利用气相色谱与质谱联用技术（GC-MS）,检测了白洋淀8种鱼类体内多氯联苯（PCBs）含量,并分析了同系物组成特征。根据白洋淀鱼类检测到同系物情况,计算毒性当量（TEQ）并进行评价。白洋淀8种鱼类体内PCBs平均含量范围是55.85~1 485.74 ng.g-1脂肪重,从高到低的顺序依次为黄颡〉黄鳝〉乌鳢〉泥鳅〉鲤鱼〉鳙鱼〉鲫鱼〉鲇鱼。在8种鱼类PCB同系物组成中,四氯联苯和五氯联苯是主要的同系物,其相对百分含量为52.0%~84.3%。这种组成模式反映了白洋淀地区有多氯联苯工业品的使用历史。8种鱼类体内PCBs的毒性当量（TEQ）范围是0.09~1 412.87 pg TEQ.g-1脂肪重,其大小顺序依次为鳙鱼〉鲫鱼〉鲇鱼〉黄颡〉黄鳝〉鲤鱼〉乌鳢〉泥鳅。结果表明,白洋淀淀区部分鱼类已经受到PCBs一定程度的污染,应引起重视。  相似文献   

10.
Two competitive immunoassays, a laboratory assay based on microwell plates and a field test based on the use of polystyrene tubes, have been developed for the detection of endosulfan in agricultural products. The limit of detection for the microwell plate format was 0.8 +/- 0.1 microg/kg, and the limit of detection for the tube format was 1.6 +/- 0.2 microg/kg. A simple, rapid, and efficient extraction method was employed, and 76-112% recoveries of spiked samples were obtained. Methanol extracts of some agricultural product samples such as grape, carrot, spinach, and tobacco could be analyzed directly by immunoassay after dilution in 0.5% fish skin gelatin-phosphate buffered saline. In contrast, extracts of green tea caused significant interference in the assay, and a number of simple cleanup methods were ineffective in removing interference. However, use of the coagulating reagent polyvinyl pyrrolidone removed the matrix effect effectively. For the validation of the enzyme-linked immunosorbent assay (ELISA) tests, samples were analyzed by ELISA and gas chromatography (GC) after solid phase extraction. The relationship between data obtained using the tube assay and microwell assay was good (the lowest r(2) value was 0.94), and also, the immunoassay assay data correlated well with data obtained from GC analysis (the lowest r(2) value was 0.93). The developed immunoassay methods are the suitable methods for the rapid quantitative and reliable determination of endosulfan residues in agricultural products.  相似文献   

11.
A monoclonal antibody-based ractopamine immunoassay has been applied to incurred samples from sheep and cattle. Results obtained by immunoassay were compared with those from high-performance liquid chromatography (HPLC). Three sets of sample extracts containing primarily unmetabolized ractopamine were analyzed. Correlation of HPLC with enzyme-linked immunosorbent assay (ELISA) for beef liver samples gave an r(2) = 0.98 despite rather low ractopamine concentrations (range 1.1-13.4 ng/mL, n = 6). Ractopamine concentrations in cow urine samples treated by solid phase extraction, to remove ractopamine metabolites, also showed a high correlation between the HPLC and the ELISA results (r(2) = 0.95, range 1.0-275 ng/mL, n = 61). In contrast, HPLC and ELISA analyses of ractopamine in sheep urine were not well-correlated (r(2) = 0.58, range 0.85-51 ng/mL, n = 34). When ractopamine conjugates in urine samples were hydrolyzed with hydrolytic enzymes, ELISA and HPLC methods were highly correlated [r(2) = 0.94 for sheep (range 123-10 554 ppb, n = 60) and an r(2) = 0.98 for cattle (range 14-8159 ppb, n = 62)]. Tissues contained only minute amounts of ractopamine, and after 7-day withdrawal periods, less than 1 ppb of free ractopamine was detected. Ractopamine was rapidly metabolized in both cattle and sheep. The difference in ractopamine concentration of urine samples before and after hydrolysis indicated that only 1-5% of ractopamine was excreted unmetabolized. Results from this study indicate that the monoclonal antibody-based ELISA could be useful for a sensitive, quantitative, or qualitative ractopamine screening assay.  相似文献   

12.
The concentration of polychlorinated biphenyls (PCB) in the soils of Moscow has been determined by gas chromatography and high-resolution mass spectrometry (GC-HRMS). The total concentrations of 19 indicator and dioxin-like congeners, as well as PCBs in surface soils, are 2.85–60.62 μg/kg (the most contaminated sample was 4591.99 μg/kg). The average value, excluding the most contaminated sample, is 14.44 μg/kg, which is characteristic of residential areas of industrialized countries. This indicator varies insubstantially depending on the functional zone of the city. The toxicity equivalent of 12 dioxin-like PCBs in soils is 1.92 ng I-TEQ/kg on average and varies in a range from 0.15 to 334.12 ng I-TEQ/kg. The fraction of PCBs in the total toxicity of dioxins and dioxin-like compounds in soil varieties is 16.7–85.4%.  相似文献   

13.
A dioxin-contaminated mineral supplement was used to study the bioaccumulation and elimination of dioxins in two dairy cows. The supplement was mixed into the total maintenance ration and fed to the cows for 40 days after which unfortified diets were fed for 40 additional days. Dioxins and coplanar polychlorinated biphenyls (PCBs) were measured twice a week in the milk and in selected tissues of the cows, one at death (day 10 of withdrawal) and one at slaughter (day 40 of withdrawal). The dioxins and PCBs were readily transferred into the milk, and at steady state, total toxic equivalents were concentrated 6-fold into the milk fat from the diet. Bioaccumulation was inversely related to chlorination number. The elimination of dioxins and PCBs in milk was biphasic. With the exception of 1,2,3,4,6,7,8-heptachlorodioxin and both octachlorinated congeners, dioxin and furan half-lives in milk were approximately 3-5 days for the alpha-phase and 35-50 days for the beta-phase. PCB-169 had a longer half-life: 11 (alpha) and 200 days (beta). When milk and feed samples from Minnesota farms that had used similar contaminated mineral supplements were analyzed, no elevated dioxin levels were found in milk. It appeared that although the dioxins from the mineral supplements have the potential to bioaccumulate, dilution into the total diet was sufficient to prevent a significant rise in the dioxin concentrations in the milk at these farms.  相似文献   

14.
High-volume enzyme immunoassay test system for sulfamethazine in swine   总被引：3，自引：0，他引：3  
A high-volume enzyme immunoassay (EIA) system for slaughterhouse screening of sulfamethazine in swine plasma/serum has been developed. The system includes a robotic sample processor that performs most of the liquid handling requirements in the assay. The assay gives good correlation with the widely used thin layer chromatographic method for determination of sulfamethazine in serum and plasma (r = 0.826). Inter- and intra-assay coefficients of variation are less than 10%. Approximately 2,400 serum/plasma samples can be analyzed in a normal working day (8 h) with this system.  相似文献   

15.
A total of 205 cornflake samples collected in Belgian retail stores during 2003-2004 were surveyed for the natural occurrence of fumonisin B1 (FB1), B2 (FB2), and B3 (FB3). These cornflake samples, originating from conventional as well as from organic production, were analyzed using an intralaboratory-validated LC-MS/MS method. Additionally, 90 cornflake samples were subjected to rapid screening using a flow-through enzyme immunoassay method to demonstrate the practicability of a screening test coupled to a validated confirmatory LC-MS/MS method for the management of food safety risks. FB(1) concentrations ranged from not detected (nd) [LOD (FB1) = 20 microg/kg] to 464 microg/kg with mean and median concentrations of respectively 104 +/- 113 and 54 microg/kg. For FB2 and FB3, the concentration ranges varied respectively from nd [LOD (FB2) = 7.5 microg/kg] to 43 microg/kg and from nd [LOD (FB3) = 12.5 microg/kg] to 90 microg/kg. Mean concentrations for FB2 and FB3 were respectively 12 +/- 8 and 21 +/- 15 microg/kg, while the median concentration was 11 microg/kg for FB2 and 19 microg/kg for FB3. From the statistical tests (chi2 and ANOVA model III), it could be concluded that the agricultural practice did not have any significant effect on the fumonisin concentrations but that the variation between different batches was significant (p < 0.0001).  相似文献   

16.
In this work, a disposable electrochemical immunosensor, based on a competitive assay scheme, was applied to detect polychlorinated biphenyls (PCBs) in food. For this purpose, antibodies against PCBs were directly immobilized onto the carbon surface of a disposable screen-printed electrode. A competition between the PCBs present in the sample and a fixed concentration of an enzyme-labeled PCB was realized and evaluated by electrochemical detection. Alkaline phosphatase was used as the enzyme label, coupled with differential pulse voltammetry (DPV) as the electrochemical technique. The immunosensor was tested on aroclor mixture detection (1242 and 1248) and then on some typologies of food samples to evaluate the possible application for real sample analysis. Samples analyzed were from different matrixes, such as sheep milk, bovine adipose tissue, and bovine muscle. Results obtained were compared with the accredited results according to ISO 17025 methods for PCB detection (HRGC-LRMS) as a confirmatory analysis. Preliminary results show the possibility to use this device as a screening method in food sample analysis. The negligible matrix effect observed may lead to a simplified extraction procedure, and considerable time and consumable savings are the immediate benefits given by the proposed method.  相似文献   

17.
Background  Adult sea lampreys, a delicate food species catch from Baltic Sea rivers, migrate from sea and spawn to sediments of still river water areas. Their larva live there four years before return to sea. The few published studies of toxicity of the sediment contaminants to the lamprey larva, however, do not include chlorinated persistent organic pollutants (POPs), thus far. Kymijoki River in southeast Finland is known for high polychlorinated POP contamination which has been measured to accumulate in several bottom fauna and fish species. Goal of the Study  To obtain the first screening results of the bioaccumulation power of POPs from sediment to lamprey larva during their life stage in the contaminated sediment. The accumulated dioxin-type of toxic load (TEQ) was also studied as a possible human hazard. Methods  Surface sediment and lamprey larva were sampled from four localities of the lower Kymijoki River and analysed for MeO-PBDEs, PBDEs, PCBs, PCDDs, PCDEs, PCDFs, and PCDTs by solvent extraction, column clean up and GC/MS procedures. The larva were sorted to seven composites according to locality and (for one place) size of the specimens (to classes of small, medium and large individuals). From the analysis results, TEQ values for composites and the bioaccumulation factors from dry sediment to fresh larva (BSAF), from dry sediment to larva lipid (BSAFlw) and from sediment organic carbon to larva lipid (BSAFoc) were calculated. Results and Discussion  TEQ load was highest (about 500 pg g-1 ww) in large larva composite due to high bioaccumulation of PCB 118, 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin (D66) and toxic penta- to octa-CDFs. A high positive significant correlation was found between weight and length of larva. Instead, lipid content had no significant correlations with weight and length of larva. Larva lipid or sediment organic carbon did not correlate significantly with any of the calculated BSAF, BSAFlw and BSAFoc values. Therefore, statistical comparisons between substance properties and bioaccumulation rate were possible for BSAF alone. These comparisons indicated a slightly significant increase of PCBs, but very significant decrease of PCDF bioaccumulation from sediment to larva by increase of the number of chlorine atoms (NCI) in the molecule. This property of highly chlorinated PCDFs indicates, as found earlier for local fish, a kinetic control of bioaccumulation by slow release from sediment back to water and the food chain. Recommendation and Outlook  The results obtained point out that bioaccumulation of POPs in lamprey larva is a possible source of toxic hazard to human food consumption and to development of lamprey species. Therefore, both larva and adult lampreys should be studied further for significance of their POP contamination compared with other experiences on impact of POPs to human and wildlife.  相似文献   

18.
An automated immunoassay for the detection of nicarbazin residues in poultry eggs and liver was developed. The assay was based on a novel all-in-one dry chemistry concept and time-resolved fluorometry. The analyte specific antibody was immobilized into a single microtiter well and covered with an insulation layer, on top of which the label was dried in a small volume. The extracted sample was added automatically to the dry microtiter well, and the result was available within 18 min. Due to the rapidity and simplicity, the quantitative immunoassay could also be used as a high throughput screening method. The analytical limit of detection for the assay was calculated as 0.1 ng mL(-)(1) (n = 12) and the functional limit of detection as 3.2 ng g(-)(1) for egg (n = 6) and 11.3 ng g(-)(1) for liver (n = 6) samples. The sample recovery varied from 97.3 to 115.6%. Typically, the intra-assay variations were less than 10%, and interassay variations ranged between 8.1 and 13.6%.  相似文献   

19.
Sample preparation affects the results of the determination of persistent organic pollutant (POP) concentrations in soils. We compared the extraction results of POPs from air‐ and freeze‐dried with field‐fresh samples. We determined the concentrations of 21 polycyclic aromatic hydrocarbons (PAHs) and 14 polychlorinated biphenyls (PCBs) in 35 horizons of forest soils (Lithosols and Cambisols) along a deposition gradient caused by a chemical factory in Strá?ske (eastern Slovakia). The organic C (Corg) concentrations of the studied samples ranged 14‐477 g kg‐1, the sum of 21 PAH (Σ 21PAHs) concentrations 53‐6870 μg kg‐1, and that of 14 PCBs (Σ 14PCBs) 0.12 96 μg kg‐1. The benzofluoranthenes were the most abundant PAHs, and the hexa‐chlorinated PCBs 138 and 153 were the most abundant PCBs. The deposition gradient was reflected by decreasing PAH and PCB storages in the organic layer with increasing distance from the chemical factory (Σ 21PAHs: 82‐238, Σ 14PCBs: 0.34‐2.3 g ha‐1). The PAH concentrations in air‐ and freeze‐dried samples were consistently lower than those in field‐fresh extracted samples. For naphthalene, this was mainly attributable to volatilization losses during drying. Naphthalene losses decreased with increasing Corg concentrations. For all other PAHs, drying reduced the extractability; the latter was correlated with the water content of the samples. The differences in most PCB concentrations among the sample preparation methods were small (within the determination error of ±15 %) and inconsistent. However, PCBs 8, 28, 52, and 209 had markedly higher concentrations in dried than in fieldfresh extracted samples. The increased recovery of low‐chlorinated PCBs in dried samples may be explained by redistribution of PCBs from higher to lower contaminated samples via the drying room atmosphere because there were no PCBs in analytical blanks. This assumption is supported by a close correlation between the octanol‐air distribution coefficient and the up to hexa‐chlorinated PCB concentrations (normalized to those in field‐fresh extracted samples) in air‐ (r = ‐0.90) and freeze‐dried (r = ‐0.86) samples. Our study shows that each sample preparation method has its specific advantages and disadvantages. Sample drying results in a standardization to a well‐defined water content and facilitates homogenization; therefore it increases the reproducibility of POP determinations. Extraction of field‐fresh samples reduces volatilization losses and contamination risks.  相似文献   

20.
A rapid and simple immunochemical method was developed for the assessment of the creatine kinase (MM) isoenzyme [CK(MM)], a protein marker linked with animal welfare and meat quality. The one-step time-resolved immunofluorometric assay produced quantitative results from serum or whole blood samples in 20 min. The analytical limit of detection (mean + 2s) for the immunoassay was 17 ng/mL (n = 6), and the functional limit of detection for the analysis of porcine whole blood samples was 426 ng/mL (n = 24). The working range of the method was linear up to 50 micro g/mL, and the within-assay precision varied between 2.1 and 10.9%. The analysis of porcine serum samples showed that the results from the immunoassay method and colorimetric CK enzyme activity determination were highly correlated (r(2) = 0.965, n = 17, p < 0.001). The practicability of the assay was demonstrated by the analysis of 300 porcine whole blood samples in a slaughterhouse environment.  相似文献   

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