Determination of thyreostats in urine and thyroid gland by ultra high performance liquid chromatography tandem mass spectrometry.

Thyreostatic compounds could be illegally administered to animals in order to obtain a weight gain due to a higher retention of water in the edible tissue and the gastro-intestinal tract. In the European Union their use for animal production is banned since 1981. Recently a highly sensitive method exploiting the determination of thyreostats with 3-iodobenzylbromide prior to purification to determine thyreostats in urine and other matrices was reported. For the first time, the UPLC instrumentation was used to separate the 3-iodobenzyl derivatives of various thyreostats. The deuterated internal standards tapazole-d(3) and propylthiouracil-d(5) were for the first time used for the quantification of tapazole, thiouracil, methylthiouracil, propylthiouracil, phenylthiouracil and mercaptobenzimidazole. The confirmative quantitative liquid chromatographic tandem mass spectrometric (LC-MS/MS) method was validated according to Commission Decision 2002/657/EC. The decision limit (CCalpha) and the detection capability (CCbeta) were found to be for all compounds below the recommended value of 10 microg kg(-1).