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Thyreostats are thioamid antithyroid drugs. The activity of these compounds consists in inhibiting the synthesis of thyroid hormones: triiodothyronine (T3) and thyroxine (T4), which favors the processes of fattening animals. The weight gain of animals is mainly due to water retention in their tissues and gastrointestinal tract. Because of the cancerogenic and teratogenic properties of thyreostatic drugs, their use for animal fattening has been banned in Europe since 1981. Control studies conducted in Poland show that thyreostats are not used in farm animals. Several cases of endogenous thiouracil content in the urine of cattle and pigs have been reported over recent years. This article presents the properties of thyreostatic compounds, discusses a possible cause of endogenous thiouracil occurrence, and provides an overview of methods used in the analysis of thyreostatic residues.
A simple and sensitive gas chromatography method was developed to determine a group of oestrogens in surface water. In the first stage of analysis, enzymatic hydrolysis of oestrogen metabolites with glucuronidase AS-HP was performed. Free compounds were extracted from 200 mL of water sample on C18 SPE column (6 mL, 1000 mg). The evaporated extract was subjected to derivatisation with a mixture of MSTFA/NH4I/DTT (1000:2:5, v/w/w). The separation of the analytes on HP-5ms capillary column was conducted. The method was validated according to the Commission Decision 2002/657/EC. Recoven in spiked samples ranged from 90% to 120 % with standard deviation lower than 30% for all examined compounds. The decision limit and detection capability of five oestrogens were in the range of 0.3-0.6 ng L⁻¹ and 0.5-0.9 ng L⁻¹, respectively. Nineteen water samples collected from different sites of several Polish rivers and lakes were tested for the presence of oestrogens. Some target compounds such as 17α-oestradiol, l7ß-oestradiol, oestrone, oestriol, and 17α-ethynyloestradiol were found in trace amounts in the analysed samples. The highest concentration observed for oestradiol reached 23 ng L⁻¹.
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