Analysis of PCDDs/PCDFs

Malisch, R., van Leeuwen, F.X.R., 2002. Third round of WHO-coordinated exposure study Analysis of PCDDs, PCDFs and PCBs in human milk. Organohalo. Compd. 56, 317-320. 

Any compound that yields ions listed in Table 5 and also elutes within the retention time window of the corresponding homologue is a potential interference. PCDDs/PCDFs are often associated with other chlorinated compounds such as polychlorinated biphenyls (PCBs) and polychlorinated diphenyl ethers (PCDPEs). These compounds may be found at concentrations several orders of magnitude higher than that of the analytes of interest and may otherwise interfere with the analysis of PCDDs/PCDFs. Therefore the retention time of the target analytes must be verified using reference standards and compared to retention time... 

Analysis of PCDD/PCDF was carried out at a certified laboratory (ERGO, Hamburg) using high resolution GC/MS methods. Identification and quantification with a dissolution method was performed following VDl procedure 3499. Sandies of bio oil and gas prior to combustion were sent to the laboratory. Gaseous contaminants were collected on a special polyurethane cartridge. 

Mannila, M., Supercritical Fluid Extraction in the Analysis of PCDD/PCDfs and PCBs in Soil and Sediment and in the Separation of Bioactive Compounds in St. John s Wort., 2003, Ph.D. Thesis, University of Kuopio, Finland. 

Sampling and Analysis of PCDDs/PCDFs, PAHs and PCBs... 

Latest developments in triple quadrupole technology make GC-MS/MS applicable for routine analysis of PCDD/PCDFs and dioxin-like PCBs in food and feed at the levels of regulatory importance. These GC-MS/MS systems have the potential to serve as a cost efficient alternative confirmatory method for determination of PCDD/PCDFs and dioxin-like PCBs in food and feed. 

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. 

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... 

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. 

Survey results need to be very carefully assessed before they can be accepted and this must take account of how the analytical methods were applied, as well as the representativeness of the samples of food of the general supply. Since analysis for PCDDs, PCDFs and PCBs in food is a particularly complex and hence expensive and time-consuming process, particular care needs to be taken that statistically sufficient samples are analysed in each survey. 

It is unlikely that future work to quantify dietary exposure and identify potential environmental sources of PCDDs, PCDFs and PCBs will be on a much greater scale than recent research unless quicker and less expensive methods of food analysis are developed for these substances. Recent developments in immunochemical techniques offer this potential. 

Birmingham B. 1990. Analysis of PCDD and PCDF patterns in soil samples Use in the estimation of the risk of exposure. Chemosphere 20(7-9) 807-814. 

Startin JR, Rose M, Offen C. 1989. Analysis of PCDDs and PCDFs in human milk from the U.K. Chemosphere 19 985-988. 

Swerev M, Ballschmiter K. 1989. Pattern analysis of PCDDs and PCDFs in environmental samples as an approach to an occurrence/source correlation. Chemosphere 18 609-616. 

Rappe C, Kjeller LO, Andersson R (1989), Chemosphere 19 13-20.. .Analysis of PCDDs and PCDFs in sludge and water samples"... 

In order to assure that retention time shifts do not adversely affect the identification of PCDDs/PCDFs, the absolute retention times of the two recovery standards added to every sample extract immediately prior to analysis may not shift by more than 10 seconds from their retention times in the continuing calibration standard (see Paragraph 17.1.4). 

Gas chromatography combined with mass spectrometry (GC-MS) is the preferred technique in the analysis of PCDDs and PCDFs and the only technique that can also be used to determine PCDE congeners reliably [ 1 ]. High resolution gas... 

The use of isotope-labeled internal standards, which is recommended in the mass spectrometric analysis of PCDDs and PCDFs, to monitor the efficiency of extraction and cleanup has not been common in PCDE analyses due to the limited number of commercially available labeled standards. A D5-labeled pentaCDE has been used as an internal standard in Finnish studies [33,113,114, 123-125,139] and 13Cl2-labeled PCDEs have been used only in few studies [120, 131]. Labeled compounds behave hke the corresponding endogenous compounds during cleanup steps and would be the best internal standards for reliable results in PCDE analysis. 

In chemical analytics PCDTs and PCTAs behave very similar to PCDDs and PCDFs. The chromatographic behavior of PCDTs is similar to that of PCDDs. Purification and fractionation with aluminum oxide and activated carbon originally developed for the analysis of PCDDs and PCDFs can be used [28,44]. 

Standard procedures developed for the analysis of PCDDs and PCDFs have been used as follows 15-20 g of ash or slag sample was Soxhlet-extracted with 220 ml of toluene for 48 h. Toluene was evaporated and the residues were dissolved in 3 ml of hexane, which was then washed three times with concentrated sulfuric acid. Activated carbon (SK-4, 80/100 mesh, Alltech) and basic aluminum oxide (Alumina B, Activity I, ICN Biomedicals) column chromatography were used for the separation of the planar aromatic compounds (PAC) fraction. The first fraction from the carbon column was eluted with 10 ml of hexane-methylene chloride (1 1 v/v) and the second fraction (PACs) with 10 ml of toluene after the column was turned upside down [26],... 

Evers EH, Berghem JW, van Ollie K (1998) Exploratory data analysis of PCDD and PCDF measurements in sediments from industrialized areas. Chemosphere 39, 459-466. 

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