Abstract: An automated radioimmunoassay apparatus which comprises:Means for time controlled incubation of a multiplicity of sample solutions, each of which comprise a mixture of (a) a sample, possibly containing an antigen, intended to be assayed, (b) a solution of a known concentration of an antigen tagged with a radioactive isotope and (c) a solution of a known titer of an antibody reactable with said antigen;Radioactivity detector means for providing a kinetic measurement of radioactivity as a solution is continuously passed therethrough, and for providing a static measurement of radioactivity as a solution is maintained statically within said detector;Means for introducing said incubated sample into said radioactivity detector means;Timing means, which is activatable by said radioactivity detector means when said detector means detects a predetermined threshold of radioactivity, for measuring time sequences and for generating control signals at predetermined time sequences;Recording means coupled to said detector m

Abstract: A method of assaying serum cardiac glycoside concentrations employing the principle of enzymatic isotope displacement from an enzymatically produced binding enzyme, a serum extract, and a labeled or isotopic cardiac glycoside. The serum extract is prepared by extracting the serum with a halogenated alkane, and partitioning the extract between a buffered solution and an aromatic hydrocarbon having a molecular weight greater than 80. The binding enzyme is made from an enzymatic preparation of whole brain by reacting the preparation with calcium, sodium, magnesium, and ATP.