Atypical antibody specificity: advancing the development of a generic assay for sulphonamides using heterologous ELISA

Development of immunoassays with broad specificity recognition of the sulphonamide drugs has proved surprisingly difficult in previous work. We have taken an antiserum specific for sulphachlorpyridazine in an ELISA system homologous for immunogen and solid phase conjugate and used it in a heterologous ELISA format. The assay proved to have broad specificity, recognising 15 out of 21 drugs tested. Despite low cross‐reactivity (<1%) for seven of the drugs tested, a fully optimised assay could prove useful as a multiresidue method for the group of drugs. The results provide evidence regarding the binding characteristics of the antibody and the immunogenicity of the target.