Towards chloramphenicol detection by inductively coupled plasma mass spectrometry (ICP-MS) linked immunoassay using gold nanoparticles (AuNPs) as element tags

This paper describes the feasibility for trace analysis of chloramphenicol using a novel immunoassay by coupling competitive measurement of chloramphenicol (CAP) to ICP-MS by the use of CAP labeled with AuNPs. Polyclonal rabbit anti-mouse immunoglobulins (anti-mouse IgG) were pre-coated on the 96-well polystyrene microplate solid support to allow the retention of mouse monoclonal to chloramphenicol (MAb-anti-CAP) antibody-CAP on the plates. Samples containing CAP as an antigen premixed with CAP-BSA protein labeled with AuNPs as an immunogenic tag were added to the MAb-anti-CAP bound solid support, physically separated from non-reacting molecules. The AuNPs were measured by ICP-MS to indirectly determine the CAP concentration in the samples. For 10 nm AuNPs, the optimal condition for CAP-BSA protein conjugation was pH 9.5 and 120 mg l ^-1 of CAP-BSA protein. The detection limit, linearity range, and precision (intra-assay, inter-assay) were 4.52 ng ml ^-1, 0-20 ng ml ^-1, and less than 20%, respectively.