An improved fully automated continuous-flow system for immunoassays.

A modification to the Southmead continuous-flow automated immunoassay system enables the bound ligand fraction to be quantitated. The bound fraction is sequentially collected, washed, and then eluted from the separating device as a bolus. The misclassification error at separation is of the order of 0.6%, and sample-to-sample interaction is negligible. The application of the modified system to the radioimmunoassay for thyroxine at a rate of 60 samples per hour is described, and satisfactory assay characteristics and performance are documented. The application of the Southmead system to the enzyme immunoassay of thyroxine and to assays for other ligands is discussed.