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Determination of the Dioxin and Polychlorinated Biphenyls (PCBs) Content of Animal Feed Samples for an EC Member State Collaborative Study.


Maximum permitted limits (MPLs) for dioxins and PCBs in animal feeds were introduced in July 2002. The European Commission has indicated these will be reviewed, no later than December 2004, in the light of new data on dioxins and dioxin-like PCBs in feed materials. In anticipation of this, the Commission has established a collaborative study in which the UK, along with other Member States, have been requested to analyse a range of animal feeds for dioxin and dioxin-like PCBs

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The University of Reading was contracted to collect the specified number of samples from a range of farms, animal feed merchants and compound feed manufacturers throughout England, Scotland, Wales and N Ireland.
A sampling plan was prepared and submitted detailing types of feeding stuff to be sampled, location, method of collection and data to be recorded. The selection of sources represented a broad spectrum of farms and feed suppliers. Feed samples from Northern Ireland were obtained by staff from the Department of Agriculture and Rural Development (DARD).
All feed samples were stored in suitable sealed containers to minimise any risk of subsequent contamination with PCBs and/or dioxins. Dry feeds were stored in cool, dry conditions until delivery to the designated laboratory. Moist feeds (i.e. forages) were stored in sealed containers at -4 C prior to dispatch, and were transported to the designated laboratory in cold-boxes.
In addition to dioxins and PCBs, the European Commission required information on fat and moisture contents of the feed materials. These analyses were undertaken in the laboratory of the Nutrional Science Research Unit according to standard recognised and approved procedures.
Samples were homogenised and aliquots were analysed for the 17 laterally substituted polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and the following PCBs:
-non-ortho-substituted PCBs - IUPAC numbers 77, 81, 126 and 169
-ortho-substituted PCBs -IUPAC numbers 18, 28, 31, 47, 49, 51, 52, 99, 101, 105, 114, 118, 123, 128, 138, 153, 156, 157, 167, 180, 189, 33, 41, 44, 60, 61, 74, 66, 87, 110, 129, 141, 149, 151, 170, 183, 185, 187, 191, 193, 194, 201, 202, 203, 206, 208 and 209
Blanks and at least one of the following reference materials (results of reference material analysis are reported) were included with every batch of samples: BCR RM 533 (for dioxins), BCR RM 534 (for dioxins) and BCR CRM 350 (for PCBs).
A final report was issued at the end of the project containing details of all samples analysed, results of reference material analyses and analytical data. The congener-specific results were reported on a whole weight basis. The individual sum toxic equivalents (TEQ) results for PCDD/Fs, non-ortho-substituted PCBs and ortho-substituted PCBs were presented on both an upper and lower bound basis.
<p>Find more about this project and other FSA food safety-related projects at the <a href="; target="_blank">Food Standards Agency Research webpage</a>.

Central Science Laboratory
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