Development and validation of a liquid chromatography tandem mass spectrometry method for the analysis of beta-agonists in animal feed and drinking water.

A reproducible, sensitive and selective multiresidue analytical method for seven beta-agonists: clenbuterol (CBT), clenpenterol (CPT), ractopamine (RTP), brombuterol (BBT), mabuterol (MBT), mapenterol (MPT), and hydroxymethylclenbuterol (HMCBT) was developed and validated by using liquid chromatography tandem mass spectrometry (LC-MS/MS) in feed and drinking water samples. The validation was achieved according to the criteria laid down in the Commission Decision 2002/657/EC, however it was necessary to use minimum required performance limits (MRPLs) proposed by the Community Reference Laboratories (CRLs) due to the lack of maximum residue limits (MRLs) for beta-agonists. By setting up these MRPLs, allows controlling their use in safe mode, since beta-agonists are commonly used in veterinary medicine sometime in a fraudulent manner, for increasing the weigh of animals. Values set for both matrices studied are 50 microg/kg for animal feed, and a range from 0.2 to 10 microg/L for drinking water. CCalpha values calculated were under the MRPLs suggested; for drinking water the lowest value obtained was 0.12 microg/L, and for animal feed 0.87 microg/kg. Values for CCbeta were ranged from 0.08 to 0.13 microg/L in drinking water and from 0.5 to 0.92 microg/kg in animal feed samples. The excellence values obtained, allowed us to conclude that the proposed analytical method is capable to control the beta-agonists studied in both matrices and that it can be successfully applied and used as a routine method in laboratories of residue analysis of veterinary food control.