| Abstract
| - When the use of tylosin as a feed additive was forbidden by Council Regulation 2821/98, the necessityof a chemical confirmation method for the monitoring of the ban was created. Recently a methodwas developed for the detection of tylosin in animal feed by means of LC-MS/MS. During the validationhigh deviating values for the decision limit, detection capability, and repeatability for tylosin in cattlefeed were observed, and the presence of urea and the formation of a tylosin urea adduct (TUA)were suggested as possible explanations. In this study two hydrolysis approaches for the TUA adductwere compared, namely, a chemical hydrolysis and an enzymatic hydrolysis with urease. The latteryielded a more complete hydrolysis of urea and was used for further validation. The recovery increasedby ∼15−25% depending on the amount of urea present in the feed (0.5−2%). The decision limit anddetection capability were hardly influenced by the enzymatic hydrolysis. Keywords: LC-MS/MS; tylosin; tylosin urea adduct; animal feed
|
