JRC-IRMM has released two new certified reference materials which will enable food testing laboratories to reliably detect and quantify stilbenes in urine.
Diethylstilbestrol (DES), dienestrol (DE), and hexestrol (HEX) are examples for stilbenes with a hormonal activity. Their use as growth promoting agents in veal and calf production is banned and the compounds form part of the national sampling and monitoring plans as stipulated by European legislation (Council Directive 96/23/EC).
The two reference materials, consisting of ERM-BB389 - DES, DE, HEX in bovine urine – and ERM-BB386 – a stilbene blank material - are preparations of new materials to replace the stilbene-containing CRMs BCR-389 (DES), BCR-390 (DE), and BCR-391 (HEX) and the respective blank materials BCR-386, BCR-387, BCR-388. Stilbene concentrations were lowered from 13 µg/kg - 34 µg/kg in the previous materials to 1 µg/kg - 6 µg/kg per substance in the new CRMs providing more confidence in the reliable high sensitivity detection of these forbidden substances. In addition, the new unit size allows for more replicates per unit to be taken.
The reference materials are intended to be used for method validation purposes (trueness estimation) and method performance control. The certified value for ERM-BB389 amounts to 1.1 ± 0.5 μg/kg (DES), 5.5 ± 1.4 μg/kg (DE), 6.1 ± 0.9 μg/kg (HEX) and is based on an inter-laboratory characterisation study; the uncertainty value contains contributions from the characterisation study, and the homogeneity and stability assessment. For the blank material ERM-BB386, the certified value was established as "< 0.6 µg/kg" (DES, DE) and "< 0.4 µg/kg" (HEX) and corresponds to the CCβ of the most sensitive method in the intercomparison. The values are traceable to the International System of Units (SI). The material has been processed and certified in accordance to ISO Guides 34 and 35. Details about material processing and certification are described in detail in the certification report .