A competitive dual-label time-resolved fluoroimmunoassay for the simultaneous determination of chloramphenicol and ractopamine in swine tissue

A novel dual-label time-resolved fluoroimmunoassay method was developed for the simultaneous determination of chloramphenicol (CAP) and ractopamine (RAC) residues in 18 swine tissue samples, using anti-CAP and anti-RAC monoclonal antibodies labeled with europium (Eu 3+ ) and samarium (Sm 3+ ), respectively. The detection limits for CAP and RAC were 0.06 and 0.25 ng/g. The recovery from swine muscle samples was 102%–121% for CAP at spiking levels of 0.1–5 ng/g, and 69.8%–85.8% for RAC at spiking levels of 1–10 ng/g. The results obtained from the swine tissue samples using this method showed good agreement with those obtained using ELISA and GC-MS, with correlation coefficients ( R ) between 0.92–0.98.