Production of 'in house' reference materials for ELISA screening of bovine urine and liver samples for clenbuterol

摘要

Clenbuterol screening of bovines is done by analysis of urine, for monitoring living animals, and liver, for monitoring animals after slaughter. ELISA has generally been used as the main method for these purposes. Nevertheless, in Europe, methods must be validated according to Commission Decision (EC) 657/2007 criteria, i.e. by use of reference materials. Production of "in house" reference materials is a possibility, but the homogeneity, storage temperature, and period of stability of these materials must be investigated in the laboratory itself. This paper reports GC-MS evaluation of an "in-house"-produced batch of aliquots of bovine urine and liver, fortified with 10.0 ng/ml and 10.0 ng/g clenbuterol, respectively, and stored at -20 degrees C and at -60 degrees C. For urine stored for 20 weeks at -20 degrees C and at 60 degrees C the stability of clenbuterol was proved at the 95% confidence level. For liver, however, it was demonstrated at the same confidence level that clenbuterol was highly unstable during storage for 20 weeks at either of the temperatures studied.