Abstract: The novel analytical devices and methods of the present invention involve dual pathway devices which provide for the confirmation of sandwich or competitive assay results. In a self-confirming sandwich assay, the labeled analyte complex becomes immobilized within a first pathway at an assay capture site to indicate the presence or amount of an analyte in the test sample. In a second pathway, a confirmatory reagent blocks the binding of the analyte or labeled analyte complex to a confirming assay site, thereby confirming that the presence of label in the assay capture site indicates a positive test sample. In a self-confirming competitive assay, a confirmed positive result is one in which the device displays a decrease in signal or no signal at the assay capture site, and the confirming assay site displays a detectable signal.

Abstract: The invention teaches a method for determining an analyte in a liquid sample via a heterogeneous assay. The sample is contacted to a carrier material which contains, in addition to one of a labelled analyte analogous substance or a labelled analyte specific substance, a detectable component which does not influence immunological reactions occurring during the course of the assay. A solid phase bound component, which is either an insufficient amount of analyte specific substance or an excess of analyte relative to analyte in the sample is contacted to the sample so as to accomplish formation of solid phase bound complexes. After separation of liquid and solid phase, label is measured in one of these, and the detectable substance is measured in the liquid. Correlation of the values obtained leads to determination of the analyte. Also described is a reagent used in the described method.

Abstract: A holder is pneumatically actuated to grasp and hold a plurality of sample containers during an analytical process which requires movement of the containers. The holder comprises a body having holes therein for receiving the caps and upper portions of the containers. Within each hole is a rigid cylindrical element and within each rigid element is a flexible tubular element. The outer diameter of the flexible element is smaller than the inner diameter of the rigid element so that a pneumatically sealed chamber is formed between the two elements when the ends of the flexible element are folded back over the ends and outer surface of the rigid element. The holder body and the rigid element are provided with holes forming a fluid passage through which positive and negative pressures may be applied to the chamber. When a negative pressure is applied to the chamber to draw the flexible element outward toward the rigid element, the cap and upper portion may move freely into the flexible element.

Abstract: A test device and method of determining the presence or concentration of a predetermined ion, such as a cation of medical interest, like sodium, potassium, calcium, magnesium or lithium, in an aqueous test sample are disclosed. The test device includes a test pad comprising a hydrophilic indicator reagent composition capable of interacting with a predetermined ion, or electrolyte, to produce a detectable or measurable response. The hydrophilic indicator reagent composition consists essentially of a hydrophobic ion specific ionophore, a hydrophobic reporter substance, and a stabilizer polymer such as gelatin. The hydrophilic indicator reagent composition, either as a film or layer, or after incorporation into a suitable carrier matrix, provides a test pad of sufficient sensitivity to the predetermined ion to achieve an accurate and trustworthy electrolyte assay of an aqueous test sample, such as plasma or serum, by a dry phase test strip assay.

Abstract: The invention concerns a method for the detection of an analyte in a sample liquid by an enzyme-immunoassay in which an enzyme-labelled compound is partitioned between a solid and a liquid phase and the amount of enzyme label in the liquid phase outside the solid phase is determined as a measure of the concentration of the analyte. The measurement is carried out in a non-porous molding having the liquid phase contained therein in contact with the solid phase. The method is particularly suitable for carrying out in a cuvette which can be filled via the porous matrix or on a test strip having a space in contact with the solid phase.

Abstract: A diagnostic test kit is disclosed for assessing whether patient chest pain is cardiac in origin and for differentiating between unstable angina and myocardial infarction at early onset of patient chest pain. The test kit comprises a receptacle for receiving and retaining a sample of blood or serum of the patient and at least three monoclonal or polyclonal antibodies suspended on a carrier. Each antibody is complementary to a different protein released by the heart muscle during early stages of a myocardial infarction and has corresponding reagents which are independently responsive to each antibody reacting the complementary protein. The combined response of reagents indicates the diagnostic condition of the patient.

Abstract: An apparatus is provided for the detection and semi-quantitative measurement of analytes. The assay results are visualized by the formation on a filter of a colored annular or circular spot, the diameter of the spot being related to the concentration of the analyte of interest. The filter on which the assay results are visualized is divided into multiple regions by strips of non-porous tape crossing the filter surface. The invention also includes a component for diluting sample to a suitable concentration for analysis, and dispensing the diluted sample onto the test filter.

Abstract: The present invention provides an analytical test strip for the detection of protein in a biological sample including a novel combination of protein error indicators. The invention includes, in combination, a partially halogenated phenolsulfonephthalein protein error indicator having nitro or nitroso substituent groups in the B and/or C rings and a merocyanine protein error indicator.

Abstract: A chromatographic test device for detecting the presence of an analyte in a liquid sample and incorporating at least two liquid-conductive zones (3, 4) which form separate liquid flow paths which deliver separate liquid streams to a region (8) in the test device during the test procedure, wherein control of the relative liquid flows in the separate flow paths is achieved, at least in part, by ensuring that at least one of the liquid flow paths is enhanced or made and/or broken or restricted during the course of the test procedure. Preferably such control is achieved by incorporating a liquid-swellable material (11) which is arranged to swell by contact with liquid sample and/or reagent and thereby to make or break contact between two liquid-conductive zones.

Abstract: A blood sampling system having an in-line sampling member is provided. The member includes a frangible joint located along the length thereof providing an easily openable port for directly sampling a donor's blood during blood collection into a collection bag. In further embodiments, an integral clamping system can be provided with the sampling member for temporarily cutting off flow of blood from a donor.

Abstract: Disclosed is a mounting structure incorporating an exposed micro-sample of a particulate dry solid of interest, including a discrete adhesive covered circular plastic disc having a uniform exposed mono-layer of the particulate solid adhered to the surface of the adhesive and a handle mounted to the opposite side of the disc to facilitate exposure and retrieval of the micro-sample to and from various reactive media. The disc, adhesive and handle portion mounting the disc are of transparent generally inert, polypropylene plastic and acrylic adhesive materials, which are chemically dissimiliar to and non-reactive with the particulate solid.

Abstract: An apparatus and method for detecting antibodies specific to non-protein antigens. The apparatus is an immunological plate containing a plurality of plastic projections coated with a non-protein material. Assays utilizing the plate are capable of stabilizing the non-protein antigens with detection levels for antibodies specific to the antigens on a nanogram level. A screening assay with the apparatus allows for early detection of exposure to non-protein materials. Specifically metallic elements are detected.

Abstract: A method and device for determining the presence of an analyte in a sample suspected of containing the analyte is disclosed. The method involves contacting a test solution containing the sample, an antibody for the analyte, and a conjugate of the analyte and a label with a contact portion of a piece of bibulous material capable of being traversed in at least one direction by the test solution through capillary action. The bibulous material contains a first receptor capable of binding to said conjugate. The first receptor is non-diffusively bound to a situs on the bibulous material separate from the contact portion. The bibulous material further contains a second receptor capable of binding the antibody to the analyte between the situs and the contact portion. The second receptor is non-diffusively bound to the bibulous material. At least a portion of the test solution is allowed to traverse the bibulous material by capillary action and thereby contact the situs.

Abstract: A test kit for determining the relative level of nitrogen of a user who is involved in a health program where diet and exercise are monitored and adjusted for optimizing physical development, the system includes a plastic stick having a first reagent zone on which is included a reactant such as urease, and a pH indicator such as bromthymol blue, and a second reagent zone on which is included a reactant indicator such as sodium nitroprusside used in conjunction with color chart blocks representing a range of urea nitrogen and ketone concentrations, wherein the user's urine nitrogen and ketone content can be determined by comparing the altered color of the reagent zone of an exposed test strip to the color chart blocks and compared with a personal baseline level, developed from a number of tests under controlled conditions, for determining the present protein nitrogen turnover and approximate balance, and the body fat metabolism.

Abstract: A method and device for determining the presence of an analyte in a sample suspected of containing the analyte is disclosed. The method involves contacting a test solution containing the sample, an antibody for the analyte, and a conjugate of the analyte and a label with a contact portion of a strip of bibulous material capable of being traversed by the test solution through capillary action. The strip contains a first receptor capable of binding to said conjugate. The first receptor is non-diffusively bound to a situs on the strip separate from the contact portion of the strip. The strip further contains a second receptor capable of binding the antibody to the analyte between the situs and the contact portion. The second receptor is non-diffusively bound to the strip. At least a portion of the test solution is allowed to traverse the strip by capillary action and thereby contact the situs.

Abstract: A device for use in a centrifuge to automatically prepare microscope slide specimens from samples of body fluids. A centrifuge tube and specimen slide are formed integrally in a unitary device. A lens clearance section is provided as a planar surface to avoid interference between the device and the rotatable lenses of a turret microscope while the device is in viewing position on the microscope stage. The device is constructed to minimize packing of sediment and other constituent elements of the sample at the entrance to the slide member and is so configured as to admit of a step during the centrifuge process which flexes the slide member to enhance the distribution of cells deposited therein.

Abstract: The present invention is a device and method for collecting and transporting biological specimens. The device provides an environment for maintaining substantial validity of a specimen during transport. The device comprises a tubular housing with an ampoule containing medium, a specimen collector and a sleeve positioned over the tubular housing. The sleeve is used to effectively break the ampoule so as to release medium into the tubular housing so as to keep a specimen substantially viable during transport.

Abstract: Disclosed is a dipstick test device for detecting an analyte in a liquid sample by treating the analyte with at least one liquid reagent to form a detectable reaction product. The device includes: a) an aqueous impermeable, aqueous insoluble reaction zone, adapted to retain the detectable reaction product; and b) a control absorbent above, and in liquid-transferring relation with, the reaction zone. The control absorbent has a predetermined, limited liquid-absorbing capacity, and the dipstick is sized and configured for insertion into a vessel containing the sample, with the control absorbent oriented above the reaction zone, so that the control absorbent fills to capacity with sample and the reaction zone incubates with the sample. The device may further include an absorbent reservoir which can be moved into liquid transferring contact with the reaction zone.

Abstract: A method disclosed for studying the interaction in solution of two molecules of the type such as a ligand and a receptor that are capable of reacting or binding with each other. The method comprises preparing an aliquot of a solution containing the first of the molecules. The second of the molecules is then added to the aliquot. A fluorescently labeled molecule is added to the aliquot, wherein the fluorescently labeled molecule is also capable of reacting or binding with the second of the molecules. A porous matrix that is optically transparent is immersed into the aliquot containing the two molecules being studied and the fluorescently labeled molecule, wherein the second molecule and any fluorescently labeled molecule bound thereto is sterically hindered from permeating the porous, optically transparent matrix, while any unbound fluorescently labeled molecule permeates the matrix.

Abstract: A biologic sample such as feces, sputum, cervical tissue, pleural fluids, exudates, cytologic specimens, or the like, is tested for the presence or absence of: ova; parasites; microorganisms; inflammatory, neoplastic tissue cells; or other target materials which are indicative of infestation, disease or infection. The sample is mixed with a buffer fluid and placed in a transparent tube which contains a volume-constricting cylindrical insert for gravimetric separation of components of the sample. The mixture is centrifuged, and the annular space between the insert and tube bore is examined under magnification for the presence of the target materials.

Abstract: A swab device, method, and kit for collecting and analyzing a sample for an analyte (antigens or antibodies) on the swab. The device includes a narrow rod or stick-like support in combination with an assay medium which is positioned adjacent to the support. The assay medium is extended longitudinally down the support a length sufficient to permit an immunoassay to be carried out within it. The assay medium and the support may include a capillary medium. A collection medium may also be attached to the capillary medium to enhance sample collection. The method includes collecting a sample suspected of containing the analyte in a sample collection area at the end of the swab. A liquid containing a labelled component is applied to the swab and allowed to immunochemically react with the sample. If the analyte is present, an immunocomplex is formed and retained on the swab. A wash solution is subsequently applied to the swab to effect the separation of the immunocomplex from excess free label.

Abstract: A multilayer diagnostic assay element wherein glyoxyl agarose, an aldehyde group - derivatized agarose, is utilized in one or more layers of the element. In a preferred embodiment the glyoxyl agarose is used to immobilize biological species such as a protein in a layer of the element.

Abstract: A method and device for testing for the presence of substances such as drugs in body fluids while simultaneously positively identifying the test subject. The device comprises an absorbent pad and a membrane mounted to the absorbent pad containing a plurality of separated areas provided with different immobilized ligand having a specific receptor site for capture or rejection of specific antigens produced by different predetermined drugs.

Abstract: An analytical device for fluid samples includes a fluid sample well means connected to a sample initiation area in such a fashion that the assay will not commence unless sufficient sample is introduced into the sample well means to conduct the assay. Once sufficient sample has been deposited into the sample well means, the sample flows into an initiation area and the assay commences.

Abstract: A method of, apparatus for and test kit for determining the presence of an analyte in a sample during an immunoassay, wherein the sample is contacted with a porous carrier carrying, an immobilized form on its surface, a binding partner for the analyte of interest, the carrier is backwashed to remove unbound material at said surface, and the presence of analyte bound to the carrier surface is determined.

Abstract: A method for determining the presence of a predetermined minimum detectible amount of one or more analytes in a sample suspected of containing the analyte is disclosed. Each analyte is a member of a specific binding pair ("sbp member") consisting of ligand and its complementary receptor. The method comprises contacting with a test solution containing said sample and predetermined amounts of two or more of a plurality of first sbp members, each respectively analogous to one of said analytes, a contact portion of a piece of bibulous material capable of being traversed in at least one direction by the test solution by capillary migration. The bibulous material contains predetermined amounts of two or more of a plurality of second sbp members, each respectively capable of binding one of the analytes and corresponding first sbp member.

Abstract: Test carrier for the analytical determination of a constituent of a sample fluid by a specific binding reaction between two binding partners having biological affinity. A plurality of test layers is so disposed that they are wetted successively by the fluid and form a fluid transport path, in which one of the test layers is a fixing layer (18) which is a porous carrier matrix. The first of the two binding partners is fixed to the latter. The fluid containing the second binding partner flows through the fixing layer (18), at right angles to its surface, on the test carrier (10).A largely complete binding reaction in an extraordinarily short time is achieved during the flow through the preferably very thin fixing layer (18) by the fact that a microporous plastics layer with a pore size P of at least 0.

Abstract: A method for improving recovery of cells from liquid suspension by centrifuqation. The method comprises coating the interior of centrifuge containers with a solution comprising an amphipathic compound prior to introduction of the cell suspension and centrifugation. The method is suited for recovery or concentration of rare cells from dilute suspensions, for example when rare cells are isolated from a sample by sorting on a flow cytometer.

Abstract: A sanitary sampling system for attachment to a tube portion of a fluid containing enclosure. The sanitary sampling system is comprised of a rigid stem portion for attachment to the tube portion of the fluid enclosure, a stopper portion having a lower portion for insertion into the rigid stem portion and tube portion, a disk-shaped orifice plate fitting for placement on the upper surface of the stopper portion and an adjustable clamp for adjustment around the stem portion, orifice plate fitting and stopper portions of the sanitary sampling system. The sanitary sampling system is designed to enable the stem portion, stopper portion and orifice plate fitting to interlock to form an air-tight and leak-free seal when the adjustable clamp is tightened.

Abstract: A microcentrifuge tube or other thermoplastic sample container having a round opening and a frictionally seated sealing lid, the lid having a size and shape to cover the perimeter of the tube opening and maintain the inside of the tube free of any contaminant. The lid viewed on an upright closed container has a downwardly extending annular portion shaped to sealing fit inside the opening, the lid further having an integral upwardly projecting lid extension configured and arranged on top of the lid to facilitate aseptic opening, grasping and identification-labeling of the container. The location, angle and size of the lid extension allow mechanical pressure to be used on top of the lid, rather than beneath the lid, to open the container. The improved apparatus and method for opening the container functions to prevent sample contamination which could otherwise occur when a fingernail or other container opening instrument is inserted beneath, and contacts some portion(s) of the underside of the lid.

Abstract: A device for the rapid qualitative and quantitative determination of the presence of a reactive ligand in a fluid.This device comprises a first reaction zone in which there is an at least temporarily impermeable membrane designed to receive a sample of test fluid and to be associated with at least one labeled reagent; a second reaction zone which is bounded on the one hand by the said membrane and on the other by a second at least temporarily impermeable membrane comprising a solid phase containing a reference reagent; and a third reaction zone which contains means for developing the reaction.A method for the rapid qualitative and quantitative determination of the presence of a reactive ligand in a fluid.Applications to the detection of the presence, in a biological fluid, of antibodies or antigens in particular.

Abstract: Methods for determining the presence and/or concentration of an analyte in a biological fluid sample are disclosed. The methods generally include admixing in solution certain polymer/reactant and reporter/reactant conjugates along with the biological fluid sample suspected of containing the analyte, thereby forming ternary complexes. The separation of the complexes from the reaction mixture is achieved through the affinity of certain selected polymer compositions for various solid phases. Upon separation, the amount of reporter activity in the solution may be measured, and therefrom the presence and/or concentration of the analyte determined. Multiple analyses on a biological fluid sample suspected of containing one or more analytes may also be performed, using either a variety of different reporters or selected polymers having varied affinity for the solid phase.

Abstract: Rapid assays for analytes of interest in a fluid sample utilize a first conjugate of a labelled reactant that specifically binds to the analyte, and a second conjugate that binds to the analyte coupled to a polymer that has an affinity for a selected solid phase. The reaction components are incubated briefly, then contacted with the selected solid phase and the labelled components determined. Optional wash steps provide for enhanced sensitivity and specificity. When the analyte of interest is an antibody to HIV, the first reactant may be a synthetic, recombinant or native HIV antigen, and the second reactant may be protein A or an anti-immunoglobulin.

Abstract: A composite device for detecting or determining the presence of components in liquids is described. The device has, in combination at least a first and a second layer of porous material in contact with each other, at least one sample receiving site in said device and at least one reaction site connected to the sample receiving site via the second layer. A pre-determined liquid flow path in and through said layer is defined by liquid barrier means located in said layers whereby liquid deposited at the sample site is transferred to the reaction site along a path from one member to the other.

Abstract: Antigens or antibodies are detected using a novel membrane based immunoassay. Known antigens or antibodies which will form complexes with antigens/antibodies to be assayed are spot filtered with pressure through a membrane. The membrane, either by itself or attached to a base material as a test strip, is incubated with a test fluid. Consequently, the resulting antibody-antigen complex is incubated directly or after an intermediate anti-antibody incubation with enzyme conjugated immunoglobulin and exposed to substrate which produces a colored insoluble product if the test target is present.

Abstract: A microassay card for a includes an upper layer containing wells for receiving a liquid sample. A second layer of the card, beneath the first layer, includes a supporting surface bound to a reactive species. A third layer includes a superabsorbent support impregnated with an indicator. Typically, the indicator is a substrate for an enzyme, such as a reduced dye precursor and a source of hydrogen peroxide necessary for the action of the enzyme upon the substrate to cause a spectral change in the absorbent layer. By selecting the structure of the first and second layers, the card can be formatted for a displacement assay or a competitive assay. The microassay card of the present invention is particularly useful for drug testing.

Abstract: A method for performing a microparticle diagnostic assay in a device having a shallow sample well for receiving a sample and reagents for forming a reaction mixture, a read well positioned adjacent to said sample well and separated from said sample well by a wall which is constructed and arranged such that when wash fluid is injected into said sample well, sample and reaction mixtures are washed from said shallow sample well, over the wall and into said read well. The steps of the method comprise forming microparticle analyte complexes in said shallow sample well; washing said microparticle analyte complexes from said shallow sample well over the wall and into said read well where a fibrous matrix retains and immobilizes said microparticle analyte complexes; adding to said read well an indicator substance capable of forming an assay signal when said microparticle analyte complexes are present; and detecting said assay signal produced by said indicator substance.

Abstract: An apparatus is provided for automatically constructing a polypeptide of high purity, up to 50 amino acids in length, using only single couplings. The apparatus includes an activation system for receiving protected amino acids, one kind at a time, having a common vessel (an activator vessel) in which to activate each of the amino acids. Also included is a reaction vessel for containing a resin used in solid-phase peptide synthesis for attaching a peptide chain thereto. A transfer system is also provided, which operates under control of a computer, to transfer the activated species from the activation system to the reaction vessel and to transfer amino acids, reagents, gases, and solvents from one part of the apparatus to another. The activator system also includes a temperature controlled concentrator vessel in which an activator solvent is replaced by a coupling solvent to enhance the coupling of the activated species to the peptide chain in the reaction vessel.

Abstract: In a simultaneous marking specific binding assay for an analyte is a liquid sample, such as urine during pregnancy or fertile period test, wherein the liquid sample is simultaneously incubated with a first specific binding reagent immobilized on a solid phase carrier surface and with a second specific binding reagent dissolved or dispersed in the liquid sample and which bears a label by means of which the result of the assay can be determined, the improvement that prior to the incubation the second specific binding reagent is contained within a layer (2a) of readily soluble or dispersible solid material superimposed on the solid phase carrier surface (2a) on which the first specific binding reagent is immobilized.

Abstract: The invention provides a disposable device for collecting, transporting and storing semi-solid or liquid specimens prior to analysis. A sample of the collected specimen is removed from the device for analysis by means of a detachable transferring stick, one area of which is the sample collecting portion of the device and another area of which is an integral handle. The device also provides for the collection of a liquid sample drained from a defined volume of a semi-solid specimen through porous screen and collected on the detachable transferring stick. A sample of the specimen or liquid from it may be flushed from the stick for a qualitative or quantitative determination of analyte. The device is useful in collecting fecal specimens and detecting occult blood therein by a determination of hemoglobin in the specimen itself or in a liquid sample drained therefrom.

Abstract: A dipping element for immunoassay or quantitative analysis of an immunoreactive analyte is disclosed having a first matrix having a carrier therein containing an immobilized antibody capable of an immunochemical reaction with a sample antigen. The immobilized antibody is not released into the aqueous liquid sample upon contact. The element further comprises a second matrix which contains labelled antigen which does dissolve in the aqueous liquid sample upon contact. On dipping, the marker-labelled antigen reacts with the immobilized antibody in competition with the antigen-antibody reaction between the analyte antigen and the immobilized antibody. if the analyte is an antibody, then the second matrix contains a marker labelled antibody and the first matrix contains an immobilized antigen. Methods for the quantitative analysis of an analyte antigen or antibody are also disclosed.

Abstract: A disposable one-time use, inexpensive, capillary-action safety micro-pipet for obtaining a sample of blood or other liquid comprises a transparent glass tube which is capable of drawing blood or other liquid into the tube by capillary action, and a resilient sheet, with an adhesive layer adhering the resilient sheet in one or more layers around the outside surface of the tube for covering the outside surface of the tube and protecting a user against being cut by any jagged edges of a broken tube.

Abstract: An optical immunosensing device for detecting the presence of an analyte in a liquid sample is fabricated by coating iron phosphate onto a silicon substrate and then etching the iron phosphate layer to obtain steps of varying thickness. Then, a first mip, capable of immunological reaction with the analyte, is immobilized on the iron phosphate steps. In the preferred embodiment, the first mip is chemically bound to the iron phosphate step surface. The presence of the analyte in the liquid sample is detected by visually observing color changes in the steps after contact of the detection zone with the liquid sample. A change in step color is related to increased thickness which can only result from the binding of the analyte to the first mip immobilized on the iron phosphate step. Aluminum phosphate can also be added to the iron phosphate.

Abstract: A method for the quantification or qualification of antigens with an immunological solid phase method, for example of the ELISA type, during which the invention seeks to overcome the difficulties with falsely high or falsely positive measurement results.

Abstract: Methods are disclosed for conducting assays. One such method comprises providing in combination a first bibulous member zone ("first zone") and a liquid medium containing a component. The first zone has non-diffusively bound thereto a reagent interreactive with the component. Conditions are selected wherein the liquid medium and at least a portion of the component contained therein traverse all of the first zone and migrate by capillary migration into a second bibulous member zone ("second zone"). The second zone is of a different composition than the first zone and is incapable of specifically binding the component except when an analyte is to be detected and the method further includes causing a reagent to become bound to the first bibulous member zone in relation to the amount of analyte present.

Abstract: Novel fluorogenic substrates for retroviral protease, e.g. HIV protease, having the chemical structure X-Thr-Ile-Nle-Phe(Y)-Gln-Arg-NH.sub.2 wherein X is a fluorogenic group and Y is an acceptor for the fluorogenic group, and their use in a fluorometric method for the determination of retroviral protease is disclosed.

Abstract: Apparatus and method are provided for the production of pairs of visual signals indicative of the concentration of an analyte in a sample for analysis. The apparatus comprises pairs of analyte detection regions, each pair of detection regions comprising a region for performing sandwich-type immunoassays and a region for performing competition-type immunoassays. The intensity of the visual signal in the sandwich-type imunoassay analyte detection region increases with increasing analyte concentration, whereas the intensity of the visual signal in the competition-type immunoassay analyte detection region decreases with increasing analyte concentration.

Abstract: An assay method and compositions are provided for determining the presence of an analyte in a sample. The analyte is a member of an immunological pair (mip) comprising ligand and receptor. By providing a first measurement surface capable of specifically binding a labelled reagent in an amount depending upon the presence of analyte in the sample and a second calibration surface capable of binding a second labelled reagent in a manner unaffected by the presence of analyte in the sample, calibration of individual tests can be accomplished simultaneously with the performance of the test itself. A signal producing system includes an enzyme, a catalyst usually bonded to a mip which defines the first labeled reagent for binding to the measurement surface and the same catalyst conjugated to a ligand capable of binding to the calibration surface. Preferably, both labeled reagents have the same composition and the calibration surface includes anti-(first catalyst).

Abstract: The performance of double receptor, specific binding assays is improved by use of a receptor complex having the structureA.sub.BL (BL).sub.n A.sub.1wherein BL is a binding ligand, A.sub.BL is a receptor specific for binding ligand, A.sub.1 is a receptor, BL is covalently bonded to A.sub.1 and A.sub.BL is reversibly bonded to BL. Generally A.sub.BL is absorbed onto an insoluble surface and A.sub.1 is an antibody to the substance being assayed. The complex has particular utility in coated tube and rechargeable radioimmunoassay systems.

Abstract: Methods and compositions are provided for concentrating particles in a minute area on a solid surface. The method permits the detection of small amounts of analytes by providing for an observable signal in relation to the concentration of particles in the area.