PCDD analysis

Recent advances in PCDD analysis of human adipose and blood analyses which can detect and possibly differentiate between background and exposure offer an opportunity to resolve some of the concerns about exposure levels in such epidemiologic studies. 

The methods, which allow in one procedure of analysis to overcome, for example, most pesticides which are used in agricultural practice in the present time, get development and introduction in practice. The contribution of the Ukrainian scientists in field of chromatographic analysis of Persistent Organic Pollutants (POPs, chlorinated hydrocarbons, PCB s) and supertoxicants, such as PCDDs, is estimated. 

The results of analysis of samples from Desnyansky and Dniper water-supply stations water are given in the report concerning the contents of PCDD and soil samples concerning the contents of triazoles. 

In general, capillary gas chromatography provides enough resolution for most determinations in environmental analysis. Multidimensional gas chromatography has been applied to environmental analysis mainly to solve separation problems for complex groups of compounds. Important applications of GC-GC can therefore be found in the analysis of organic micropollutants, where compounds such as polychlorinated dibenzodioxins (PCDDs) (10), polychlorinated dibenzofurans (PCDFs) (10) and polychlorinated biphenyls (PCBs) (11-15), on account of their similar properties, present serious separation problems. MDGC has also been used to analyse other pollutants in environmental samples (10, 16, 17). 

Stalling, D.L., R.J. Norstrom, L.M. Smith, and M. Simon. 1985a. Patterns of PCDD, PCDF, and PCB contamination in Great Lakes fish and birds and their characterization by principal components analysis. Chemosphere 14 627-643. 

For decades, many countries and intergovernmental organizations have taken measures to prevent the formation and release of PCDD/PCDFs, and have also banned or severely restricted the production, use, handling, transport and disposal of PCBs. As a consequence, release of these substances into the environment has decreased in many developed countries. Nevertheless, analysis of food and breast-milk show that they are still present, although in levels lower than those measured in the 1960s and 1970s. At present, the major source of PCB exposure in the general environment appears to be the redistribution of previously introduced PCBs. 

Several attempts have been made to set up immunochemical techniques for dioxin analysis (reviewed in [230,238,239]). Frequently the detectability and selectivity accomplished have not been considered appropriate for the direct analysis of environmental samples. We should notice that due to the poor solubility of PCDDs and PCDFs in water, the levels of these contaminants in aqueous samples is very low. For this reason analysts usually prefer the use of chromatographic and spectrometric methods that perform using organic solvents. However, the speed and high sample throughput that can be accomplished with the immunochemical methods have prompted several research groups and companies to establish immunochemical methods. 

Bergqvist, P.-A. Strandberg, B. R pe, C. 1998, Lipid removal using semipermeable membranes in PCDD and PCDF analysis of fat-rich environmental samples. Chemosphere 38 933—943. 

The relative ratio of regioisomers of PCDD/F and other chlorinated compounds formed in incinerators is called the incineration pattern. The pattern can be derived from statistical analysis of a large number of measurements of the same plants, and can be used for elucidation of thermal formation mechanisms in plants. In principle regioisomers can be formed either by stereospecific chlorination or dechlorination processes. The pattern has also been used as a part for explaining of the formation mechanism of PCDD/F and other chlorinated compounds formed in incinerations (see Figure 8.4). 

GC-EI-MS permits the direct analysis of mixtures, e.g., to analyze synthetic byproducts an advantage that made GC-EI-MS benchtop instruments become widespread in modem synthetic laboratories. The GC-EI-MS combination is especially successful in monitoring environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-dioxins (PCDDs), polychlorinated dibenzofuranes (PCDFs), or other volatile organic compounds (VOCs). 

A few gas chromatography (GC) and liquid chromatography (LC) studies have been reported. Eor example, PCDDs have been separated on a 50m x 0.25 mm polar fused silica capillary GC column (CP Sil-88, Chrompack) with helium as carrier gas and Fourier transform infrared (FTIR)/MS detectors <1997ANC1113>. Furthermore, a highly sensitive and accurate GC-MS method for rapid quantitative analysis of 1,4-dioxane in water has been described <1997JCH(787)283>. 

For the determination of the intralaboratory repeatability of the DR CALUX bioassay for sediment samples, two sediment extracts were analyzed 10 times. Each analysis was performed in triplicate. As a prerequisite for a correct triplicate analysis, the percentage standard deviation in the triplicate determination should be below 15%. This is in accordance with the harmonized quality criteria for eell-based bioassay analyses of PCDDs/PCDFs in feed and food as formulated by Behnisch et al. (Behnisch et al, 2001 a) and as detailed in European Union directive 2002/69/ EC and direetive 2002/70/EC. The repeatability for the low-2,3,7,8-TCDD-content sediment... 

Besselink, H., Leonards, R, Felzel, E., Brouwer, B. (2002). Analysis of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofiirans (PCDF) and biphenyls (PCB) in fish using DR CALUX and GC/ MS Acomparison. Organohalogen Compounds 58 412 15. 

Stevens, J.L., Green, N.J.L., Bowater, R.J., Jones, K.C. (2001). Inter-laboratory comparison exercise for the analysis of PCDD/Fs in samples of digested sewage slrrdge. Chemosphere 45 1139-1150. 

Rappe et al. have reported on the analysis of two commercial chlorophenate formulations from Scandinavian sources using a 50. m OV-17 column (7). The tetrachlorophenol was known to contain approximately 5 2,U,6-tri-, 50 2,3,l, 6-tetra- and 10 pentachlorophenol as their sodium salt. The combined levels of PCDDs and PCDFs (tetra- to octa-) were 10 and l60 yg/g, respectively. Whereas on the earlier analyzed PCP samples 0 0 ] the... 

Studying occupational exposure to highly contaminated chlorophenols, the analysis of PCDDs and PCDFs in blood samples seems to be a better parameter to follow than the level of chlorophenol in the urine. 

For the quantitative determination of polychlorinated diben-zodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), sample treatment and conservation play crucial roles, too. Only some of the 75 PCDD isomers and 135 PCDF isomers are highly toxic. The collection and analysis of the hazardous compounds present at ultratrace levels in environmental samples must preferably be isomer-specific. The exposure routes for these compounds originate from combustion processes (18-19). 

Rappe (25) summarized all the literature with regard to the analysis of polychlorinated dioxins and furans and concluded that, with the standards now available, isomer-specific analyses can be performed for all toxic PCDD and PCDF isomers. However, some attention still has to be focused on characteristics of analytical and concentration techniques that can be promising for the future (26). 

Holmstrand H, Gadomski D, Mandalakis M, Tysklind M, Irvine R, Andersson P, Gustafsson O (2006) Origin of PCDDs in Ball Clay Assessed with Compound-Specific Chlorine Isotope Analysis and Radiocarbon Dating. Environ Sci Technol 40 3730... 

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