Reference materials for PCDD and PCDF analysis: production and verification of the contents of twelve congeners in iso-octane reference solutions

Summary The Community Bureau of Reference (BCR) of the Commission of the European Communities has produced standard solutions of PCDDs and PCDFs (dirty dozen) to guarantee proper calibration and traceability of results in the certification of these compounds in matrix materials. The purity of each individual isomer has been evaluated on the initial crystals using several analytical methods. Solvents have been checked for impurities. The entire procedure of preparation of the twelve solutions has been performed under strict metrological conditions and will be published elsewhere. All results and the preparation procedure followed are described. The solutions are not certified, but may be obtained from BCR together with an analytical report.