Abstract: A lateral flow chromatographic assay format for the performance of rapid enzyme-driven assays is described. A combination of components necessary to elicit a specific enzyme reaction, which are either absent from the intended sample or insufficiently present therein to permit completion of the desired reaction, are predeposited as substrate in dry form together with ingredients necessary to produce a desired color upon occurrence of the desired reaction. The strip is equipped with a sample pad placed ahead of the substrate deposit in the flowstream, to which liquid sample is applied. The sample flows from the sample pad into the substrate zone where it immediately reconstitutes the dried ingredients while also intimately mixing with them and reacting with them at the fluid front. The fluid front moves rapidly into the final “read zone” wherein the color developed is read against predetermined color standards for the desired reaction. Pretreatment pads for the sample, as needed, (e.g.

Abstract: In an improved method for clearing a field of observation or treatment of unwanted color or other extraneous material, a chromatographic strip of paper, plastic, glass or like material, with or without simultaneous deposit of adjuvant or reactants on the cleared field, the strip is immersed to a level just barely above the juncture of the zone to be cleared with the preceding zone of the strip in a chase liquid, such as water containing adjuvant if desired. Where red blood cells containing parasitic pathogens such as cholera parasites are to be assayed, a lysing step is performed on the same strip prior to the clearing strip.

Abstract: Superparamagnetic (“SPM”) subunits of 1-30 nm average mean diameter (e.g. ferro fluid) subparticles are treated with a magnetically noninterfering substance capable of coating and covering them (e.g, BSA) and they spontaneously form agglomerates of about 100 nm to about 450 nm or higher average mean diameter and are then used to form complexes with target biological ligands such as viruses, contained in large volumes of liquid. The complexes are subjected to the gradient intensity of a strong magnetic field, and excess liquid is removed, where upon an immunochromatographic assay is conducted to determine the identity and/or amount of target ligand present, in which operation SPM particles that bonded to the ligand function as tags for ligand detection.

Abstract: An assay device for detection or determination of an analyte in a sample uses either removably attachable components or hinged panels to provide greater flexibility and reduce manufacturing and storage costs. In one embodiment of the device, the device comprises: (1) a first opposable component including:(a) a first panel; (b) a second panel mounted on the first panel generally parallel to the first panel with space between the first and second panel, the second panel having an opening forming a first receptacle for a sample collection device; and (c) a second receptacle for a test strip formed by the first panel and the second panel; and (2) a second opposable component hingedly attached to the first opposable component. In this device, the first and second opposable components can be brought into operable contact so that fluid is expressed from the sample collection device and applied to the test strip for detection or determination of an analyte by a test performed on the test strip.

Abstract: A chromatographic assay device for use with immunoassays allows rapid and convenient assays of analytes of biological interest, and permits extractions to be carried out in situ, avoiding the use of separate extraction vessels. The device has a wide dynamic range and avoids interference from particulates or colored components. In one form, the device comprises: (1) a first opposable component comprising a sample preparation zone adapted to receive a sample to be assayed; and (2) a second opposable component comprising a chromatographic medium. The first and second opposable components can be brought into opposition so as to cause the sample preparation zone to apply the sample to be tested to the chromatographic medium. Preferably, the analyte is detected with a visually detectable label.

Abstract: The invention pertains to an immunoassay method for determining the presence of volatile organic compounds in aqueous, soil and air samples by simultaneously collecting and testing a sample volume suspected to contain such organic compounds. As a major problem in the assay of such materials is their rapid evaporation, the present immunoassay is specifically designed to eliminate or minimize the evaporation of the volatile organic analyte during sample handling as well as during the assay process itself. The immunoassay method is based on an assay vessel which has a lower portion, in which the immunoassay actually takes place, and an inert upper portion, which can hold a sufficiently large volume of sample to prevent or minimize evaporation of the organic compound from the smaller volume in the lower portion.

Abstract: Methods and kits for performing a ligand/anti-ligand assay are described. The ligand/anti-ligand assay comprises: (1) simultaneously carrying out the extraction of a ligand from a sample of cells or cells and reaction of the ligand with at least two anti-ligands therefor to form a detectable reaction product, and (2) detecting the reaction product.

Abstract: A method for performing multiple, simultaneous in vitro diagnostic tests is provided. The method utilizes a solid phase device comprising a receptacle and an insert. The receptacle has one or more fixed components immobilized on its inner surface. The insert has one or more fixed components--different from those immobilized on the receptacle--immobilized on its surface which is in contact with a fluid sample when inserted therein. The test is performed by placing a fluid sample, having two or more mobile components reactive with the fixed components, into the receptacle and in contact with the insert for a period of time and measuring the changes which are a function of the concentration of the mobile components.

Abstract: An improved method for performing an in vitro diagnostic test is provided. The method utilizes a solid phase device having a fixed component immobilized on its surface which is in contact with a fluid sample when inserted therein. The improvement resides in utilizing a receptacle, into which the device is inserted, having the same fixed component immobilized on the inner surface of the receptacle. The test is performed by placing a fluid sample, having a mobile component reactive with the fixed component, into the receptacle and in contact with the insert for a period of time and measuring a change which is a function of the concentration of the mobile component.

Abstract: A method and apparatus for conducting chemical reactions at a liquid-solid interface wherein a reaction component is fixed on the surface of a solid phase immersed in a liquid phase containing a freely diffusing, mobile reaction component. The apparatus comprises a substantially smooth-surfaced matrix of appropriate geometrical configuration designed to provide a large surface to volume ratio, a short transfer distance from the mobile component to the fixed component distributed on the solid phase surface and to drain freely upon removal from the reaction liquid.

Abstract: A method and solid phase matrix is disclosed which has special utility for use in conjunction with automatic pipetting apparatus for conducting reactions at a liquid-solid interface. A reaction component is fixed on the surface of the solid phase matrix which is wetted by a liquid phase containing a freely diffusing, mobile component. The matrix is comprised of a support surface to which are attached a plurality of inwardly projecting fins. The innermost extension of the fins defines a centrally located well into which an automatic pipetting apparatus may be inserted. The method may be used for qualitative or quantitative determinations of the mobile component contained in a liquid which wets the solid phase matrix.

Abstract: Method of determining the presence and/or concentration of a polyvalent antigenic substance in a fluid. The method comprises the steps of incubating the fluid with labeled antibodies to the substance to form a first labeled immunochemical complex and then incubating that complex with immobilized antibodies to the substance to form a second labeled complex which is separated from the incubation medium. The amount of label in the second complex provides a means for detecting and/or quantitating the substance in the fluid. By reversing the sequence of incubation steps in a "two-site" or sandwich assay, greater sensitivity is achieved and an intermediate washing step is eliminated.

Abstract: Reagent and method for detecting the presence of hepatitis associated antigen (HAA) in blood serum. The reagent comprises anti-HAA antibodies coupled via an intermediate silane to a plurality of siliceous particles having a surface area of at least about 1 m.sup.2 /g and, if the particles are porous, an average pore diameter of at least about 1000 A. The test method comprises the steps of incubating a serum sample with the reagent to complex any HAA in the samplewith the antibodies of the reagent, incubating the reaction product with a solution of radio labelled anti-HAA antibodies to complex the labelled antibodies with any HAA that may be complexed to the reagent, separating the incubation products from the solution of labelled antibodies, and counting the radioactivity of either the separated products or the remaining solution to determine whether HAA was in the sample.