LAUSR

Hair analysis has attracted great attention in regulatory analysis of food producing animals, especially due to the wider detection window of veterinary drugs in this matrix and also to the possibility of confirming parent drugs with minimum metabolization. This work involved the development and validation of a quantitative LC-MS/MS method to determine 25 steroids and steroid esters in bovine hair. Sensitivity was improved using a fast and effective microwave-assisted chemical derivatization with methoxyamine hydrochloride. The validation was conducted in accordance with the Decision 657/2002/EC guidelines. An animal experimentation procedure was performed on twelve bovine animals in which two commercial formulations containing boldenone undecylenate and testosterone propionate were administrated via intramuscular injections on the neck. The samples were collected over a period of 78 days, in which the detection of the administrated analytes was only observed nearby the application sites. For some of the monitored days no analyte was detected on the neck area. Since the migration of the analytes was not observed to areas other than the application site, false negative results should be carefully considered when monitoring animal hair samples.