BETA-AGONISTS IN ANIMAL FEED .3. OPTIMIZATION OF THE CLEANUP AND THE END-DETERMINATION STEP

This study represents the second part of an interlaboratory study inte nded to develop an official modular Community confirmatory method for the detection of beta-agonists in animal feed. Homogeneous pools of pr imary extracts were prepared by means of an extraction module based on the conclusions of a previous part of this work. The primary extracts were further processed by four laboratories each using a different cl ean-up scheme. The final extracts thus obtained were cross-distributed between the same laboratories and measured either by GCMS or HPLC. Tw o laboratories (B and D) applied separate clean-up schemes for clenbut erol and salbutamol. All clean-up schemes for clenbuterol were found t o be compatible with all end-determination steps. In contrast, for sal butamol clean-up method D was found not to be compatible with the end- determination steps applied by laboratories B and C. The results of th is study have clearly demonstrated that the clean-up methods for both clenbuterol and salbutamol applied by laboratory B yielded superior re coveries with an acceptable standard deviation. Therefore, in conclusi on to this study, the participating laboratories recommend the clean-u p schemes applied by laboratory B to serve as part of the official Com munity confirmatory method.