PROFICIENCY TESTING FOR DIOXIN LABORATORIES DETERMINATION OF POLYCHLORINATED DIBENZO-P-DIOXINS AND DIBENZOFURANS IN SEWAGE-SLUDGE

Commissioned by the Ministry for the Environment Baden-Wurttemberg a p roficiency testing on the analysis of polychlorinated dibenzo-p-dioxin s (PCDD) and polychlorinated dibenzofurans (PCDF) was carried out. Wit h sixty participating laboratories from eight countries, mainly from t he Federal Republic of Germany, this study is the largest proficiency testing in the field of dioxin analysis ever organised. In the study i nvolved were the determination of the seventeen 2,3,7,8-substituted PC DD/PCDF congeners, the toxicity equivalent according to NATO/CCMS (I-T EQ) and of the homologue groups of the tetra- to heptaCDD/CDF. The lab oratories were instructed to use their preferred method of clean-up an d quantitative determination of PCDD/PCDF. No significant influence of the type of mass spectrometric equipment (high or low resolution GC/M S) or of the type of capillary column (polar and/or non-polar) or any combination of capillary columns upon the quality of the analysis meas ured by the z-score of the I-TEQ values is apparent. According td a pr oposal of the IUPAC and derived from the Ordinance on Sewage Sludge (A bvKlarV), the fulfilment of the Q-score and the 'z-score 75%' was defi ned as the decisive quality criterion for successful participation in the proficiency test. 41 participants (according to 68%) met this qual ity criterion for both sewage sludge samples. (C) 1998 Elsevier Scienc e Ltd. All rights reserved.