EN
Studies on the effects of freezing meat with spiked hormones at residue levels have been made. Beef and poultry meat samples which contained diethylstilbestrol and 19-nortestosterone were stored frozen at -20°C. The hormones were quantified by high-performance liquid chromatography with UV detection after 2, 4 and 6 months. Diethylstilbestrol is stable under all of these conditions and shows only minor losses. There is a remarkable decrease in concentration of 19-nortestosterone in beef after 4 months. From the results it can be concluded that meat samples intended for hormone residues analysis, when stored frozen for a long period, can give false negative results for some compounds.