BETA-AGONISTS IN ANIMAL FEED .4. INTERCOMPARISON STUDY OF A CANDIDATEREFERENCE CONFIRMATORY METHOD

The objective of this intercomparison study was to evaluate the qualit ative aspects and the interlaboratory performance of the method select ed to be recommended as the official Community reference confirmatory method for the analysis of beta-agonists in animal feed. This method c ontains three possible options, i.e. a narrow range method for clenbut erol-type compounds based either on HPLC or on GCMS as the end-determi nation step and a broad range GCMS method for clenbuterol-type and sal butamol-type-beta-agonists. Three types of animal feed materials were provided: st series of blank materials and two series of materials con taminated with clenbuterol and salbutamol at a low and a high level, r espectively. The results showed that the majority of the laboratories were able to identify blank low and high level materials both for clen buterol and salbutamol. For clenbuterol the narrow range GCMS method h as been shown to be the most satisfactory. Although the participants h ad comments on the purity of the extracts obtained by means of the bro ad range method it was found appropriate as a multi-residue method whi ch is able to measure simultaneously clenbuterol-type and salbutamol-t ype beta-agonists. A statistical evaluation of the quantitative measur ement was also performed.