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Natural occurrence of thiouracil in bovine and swine urine in Poland was investigated. Under the national residue control programme, 537 urine samples were tested. In 77 samples (14.3%) thiouracil was detected above decision limit CCα (0.91 µg L⁻¹), including eight samples over the recommended concentration of 10 µg L⁻¹. Of the bovine urine samples, 95 and 99 percentiles have thiouracil concentration below 4.50 and 14.85 µg L⁻¹, and of porcine samples below 2.35 and 6.80 µg L⁻¹, respectively.
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.
Sensitive and selective methods for the screening (GC-MS) and confirmatory analysis (GC-MS/MS) of 17α- and 17ß- trenbolone in bovine urine were developed. In the first stage of the analysis, the enzymatic hydrolysis of trenbolone metabolites with glucuronidase AS-HP in acetate buffer (pH 5.2) solution was carried out. Free compounds were extracted from urine with diethyl ether. For the purification of the extract solid phase, extraction with C18 and NH2 columns was applied. The evaporated extract was subjected to two derivatisation steps; the first with MSTFA/12 solution and second with MSTFA. The separation of the analytes on HP-5 ms capillary column was conducted, llie methods were validated according to the Commission Decision 2002/657/EC. For GC-MS method, CCα and CCß were 0.21-0.36 µg L⁻¹ for 17α- trenbolone and 0.20-0.34 µg L⁻¹ for 17β- trenbolone, while for GC-MS/MS method the values were lower and amounted to 0.15-0.25 µg L⁻¹ for 17α- trenbolone and 0.20-0.34 µg L⁻¹ for 17ß-trenbolone. Method recoveries in spiked samples ranged from 86%-111% with standard deviation lower than 25% for both detection techniques.
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