| abstract |
A method and test means for determining a specific binding substance, such as an antigen or hapten, in a liquid sample wherein a solid, nonspecific adsorbent is contacted, preferably in sequence, with the sample and a labeled form of a binding partner for the substance to be determined, such as a labeled antibody. The amount of label which becomes associated with the adsorbent by binding of the labeled binding partner to the adsorbed substance to be determined, i.e., in a sandwich fashion, is a function of the amount of the substance to be determined in the liquid sample. Preferably, the adsorbent is an ion exchange material, and the assay steps are carried out under pH conditions between the isoelectric points (pI values) of the substance to be determined and the labeled binding partner. The method and test means are particularly suited for the detection of hepatitis B surface (HBs) antigen, especially where the label is a radioactive material and a column format is employed. The resultant radioimmunoadsorbent (RI-AdTM) assay and test means for HBs antigen offers significant manufacturing and user advantages over the prior art methods and test means. |