Interlaboratory comparison study on dioxins in cow's milk 730501044

Interlaboratory comparison study on dioxins in cow's milk

[ Interlaboratorium vergelijkingsonderzoek naar dioxines in in koe melk ]

de Jong APJM, Liem AKD, Hoogerbrugge R

17 p in English 1992

RIVM Rapport 730501044

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Toon Nederlands

English Abstract
Six laboratories in four European countries (GER, GB, S, NL) have conducted an interlaboratory comparison study on the analysis of dioxins in cow's milk. The study comprised a cross comparison of standards and the analysis of the 2,3,7,8-substituded congeners of have used their own procedures and methods for fat and dioxin determination in biological samples, all using non-polar gas chromatography and medium to high resolution mass spectrometry (RP = 3.000-10.000). Quantification was preformed by the use of a common quantification standard mixture of the native PCDD/Fs (4 labs) or the own quantification standards (2 labs). Within- laboratory reproducibilities for the determination of the major toxic isomers and the total TCDD toxicity equivalence (TE) level were between 2 and 16% (relative standard deviation (RSD)) with a mean of 8%. The interlaboratory variability in TE values was less than 12% (RSD) for TE values between 2.8 and 10.4 pg/g milk fat. The reliability of participant standards was difficult to assess and probably less good than expected. Deviations between found and expected concentrations in these standards were on average within 25% and for some congeners to 50% in some laboratories, when quantified against a common standard.

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