Abstract: A method of determining a ligand of interest in a ligand is described. The method, which makes it possible to detect and quantify a ligand in a liquid, makes use of a biotin-avidin system which can be used to carry out immunoassays in both heterogeneous and homogeneous format. The basic components used in the method are a biotin-labeled substance (which is biotin-lableled ligand or biotin-labeled specific binding partner), biotin-labeled fluorophore, a liquid to be analyzed for the ligand of interest, specific binding partner for the ligand of interest and avidin.

Abstract: An apparatus for transferring beads employed in a radioimmunoassay is disclosed. The apparatus comprises a receptacle tray 30, test tube rack 48 and plurality of test tubes 42. The receptacle tray 30 contains an array of wells 32, which may be marked individually with indicia such as numerals and colors, and two alignment holes 34 and 35. The test tube rack 48 contains an array of columns 51 in a pattern corresponding to that of the wells 32 on tray 30. Test tube rack 48 also contains two alignment pins 52 and 53 for insertion into alignment holes 34, 35. Each of the test tubes 42 are generally cylindrical but have a gradually increasing diameter from bottom to top so that they can be inserted into rack columns 51 with a friction fit.

Abstract: Automated chemical analytical method and device in which a precise measured quantity of reagent is combined with an assay medium. Prior to such delivery, the reagent, being water-soluble or dispersible, is contained within carrier solid organic binder which is fixed within and constitutes part of the device. Upon addition of an aqueous medium, the carrier binder is dissolved or dispersed, the protected precise measured quantity of reagent is concomitantly released and dissolved.

Abstract: Addition of a low concentration of an alkali metal metabisulfite completely stops color development in a peroxidase-labeled immunoassay wherein the peroxidase catalyzed reaction comprises oxidation of an achromatic substrate to the corresponding chromatic product in the presence of a peroxide.

Abstract: Device for delivering precise measured quantities of a plurality of reagents with each reagent being incorporated in a device and each being water soluble. The device has a water impervious support secured to one or more faces of which are discrete and separate elements each containing water soluble or dispersible binder and dispersed therein a water soluble or dispersible reagent. The reagent of each element in the device is reactive with at least one constituent in an assay medium or with at least one other reagent on the device. The device is used by contacting it with the assay medium until the elements dissolve completely.

Abstract: A method for determining the presence of a ligand in a liquid medium which utilizes enzyme labeled avidin and biotin labeled reagent in a specific binding process wherein the ligand to be detected is contacted with an insoluble phase containing specific binding substance for the ligand. Various protocols may be used to assay the resulting enzyme activity which is related to the amount of ligand in the liquid medium.