Production and stability testing of incurred reference materials for the anabolic steroid trenbolone in bovine urine

The production of stable reference materials with incurred residues of vete rinary drugs is necessary for the validation of methods of analysis, includ ing the determination of critical performance characteristics. A reference material for trenbolone in bovine urine was produced and the long-term stab ility was tested. From a pilot 16 week stability study on seven batches con taining different additives it was concluded that the use of preservatives does not improve the stability of the residue. A final batch of reference m aterial of 800 vials each containing 5 mi of urine with a target concentrat ion of 5 mu g 1(-1) was prepared. The homogeneity and long-term stability o f the material were tested. The material was found to be homogeneous. Based on the results of a 52 week stability study it was concluded that the mate rial is stable, using the current analytical methodology. For the developme nt of reference materials, highly accurate and precise analytical methods a re necessary. However, the current analytical methodology is not suitable f or full evaluation and certification. Currently, a new LC-MS method is bein g developed. After validation of this method, the stability and homogeneity study will be repeated.