A heterogeneous, competitive binding immunoassay is conducted with a dry analytical element. The immunoassay is useful for determining a ligand (e.g. a therapeutic drug) and includes contacting a finite area of the element spreading layer with a sample of a liquid in the presence of a labeled ligand analog and an immobilized receptor. An immobilized ligand-receptor complex is formed within the finite area. Simultaneously, the uncomplexed ligand migrates horizontally away from the immobilized complex which remains in the center of the finite area. At least five seconds after the completion of the contacting, the amount of immobilized complex is measured in the center of the finite area.
The invention relates to a latex agglutination method for the detection or determination of one partner of an antigen-antibody reaction, wherein, in order to suppress non-specific reactions, to, for example, Clq and rheumatoid factors the immunochemical reaction takes place in the presence of an immune complex which does not contain any antibody or antigen that is specific for one of the partners.
Am improved device and method for analyte assay in liquid samples, wherein a porous membrane with an immobilized receptor which is capable of directly or indirectly binding to the analyte is separated from a body of absorbent material capable of absorbing the liquid sample by a septum capable of substantially separating the porous membrane from the absorbent body while substantially directing the flow of the liquid sample from the porous membrane to the absorbent body.
The invention is directed to new drug hapten analogues comprising: (A) an active ester group; (B) a drug hapten nucleus selected from a hydantoin nucleus or a barbiturate nucleus and (C) a linking chain linking the 3-position of the drug hapten nucleus to the active ester group.
A method for the detection of a compound which modulates binding of a ligand to a biological receptor, which method comprises contacting the ligand, biological receptor and test compound at a locus on a solid phase matrix, the matrix allowing movement of fluids therein by capillary action, under conditions which permit binding of the ligand to the biological receptor and partition of any unbound ligand on the solid phase matrix, and detecting any modulation of binding by the test compound by reference to any such partition.
A method of separating bound labeled indicator from free labeled indicator in a layer of a test element for immunoassay. The method comprises a) depositing sample containing a target immunoanalyte capable of binding to the labeled indicator or to an immobilized antibody in competition with the labeled indicator, onto an exterior surface of a test element in the presence of the labeled indicator and b) adding an amount of wash liquid to the exterior surface to form a pool of the liquid having a meniscus on the surface, the liquid penetrating the surface over an area bounded by a closed intersect edge formed between the pool meniscus and the surface, so that penetrating liquid can push free labeled indicator away from bound labeled indicator in a volume of the layer below the bounded area. The method is improved in that the step b) comprises i) depositing a first amount of wash liquid at a first location on the surface in a pool, (ii) allowing at least a portion of the pool to spread out through a first portion of the test element to wash out free labeled indicator, and then (iii) depositing a second amount of wash liquid at a second location on the surface different from the first location to spread out through a second portion of the test element different from the first portion, so that the intersect edge is displaced over the surface over time and the liquid flowing into the test element at the intersect edge sweeps through more of the target read area than is the case when washing from only the first location, thus reducing background signal due to non-separated free labeled indicator remaining in the volume.
