Determination of thyreostats in muscle and thyroid tissues by QuEChERS extraction and ultra-performance liquid chromatography tandem mass spectrometry.

The use of thyreostats as veterinary drugs is banned in the European Union since 1981 because of their carcinogenic and teratogenic properties. Controlling their illegal use in breeding animals is quite difficult because of their low molecular weight, high polarity and the presence of tautomeric forms. To harmonise the performance of analytical methods, the recommended concentration for thyreostats such as thiouracil, methylthiouracil, propylthiouracil and tapazole established by the Community Reference Laboratory in 2007 is 10 ng g(-1).

Development, validation and data quality assurance of screening methods: a case study.

Despite the growing importance of qualitative screening tests in routine laboratories involved in the EU official control, their validation is not as deeply explained in Commission Decision 2002/657/EC as the validation of quantitative confirmatory methods. At the same time, the issue of quality assurance of screening assays defining internal quality control (IQC) procedures as required by accreditation bodies is undoubtedly less developed in this analytical field. As an example the present study describes the development, the validation and the IQC implemented for a commercial enzyme linked immunosorbent assay (ELISA) able to detect 17-α-19-nortestosterone (α-NT) and 17-β-19-nortestosterone (β-NT) isomers in bullock urine.