Reference standards for residue analysis of chloramphenicol in meat and milk: a critical study

A collaborative study was organised, according to the ISO 5725 protocol, for the evaluation of methods of residue analysis of chloramphenicol on a national basis and as potential reference methods for the European Community. The methods to be examined were RIA and HPLC. Reference samples were prepared with defined contents of chloramphenicol in the order of 1 μg/kg in milk and 10 μg/kg in meat, respectively. The analytical methods used for the determination of the “true” value of chloramphenicol contents were radioimmunoassay (RIA) and gas chromatography with either electron capture detection (GC/ECD) or mass specific detection (GC/MSD). Each concentration level was analysed 16 times by RIA, 5 times by GC/ECD and twice by GC/MSD. An additional object of our studies was the examination of the packed and coded samples for homogeneity. The influence of duration and temperature of storage and the influence of irradiation were investigated.