Abstract: Kits are provided for prenatal screening tests for risk of Down's syndrome which are carried out on a maternal serum sample obtained before the beginning of the third trimester of pregnancy. The kits contain immunoassay means to determine alpha-fetoprotein, unconjugated oestriol, human chorionic gonadotrophin, and/or dehydroepiandrosterone sulfate (DHEAS).

Abstract: A device for performing an enzyme-labelled binding assay comprises an absorbent material and a developing solution, wherein the absorbent material is provided with a plurality of reagent zones including an indicator reagent zone, and is capable of transporting the developing solution by capillary action sequentially through each reagent zone, and wherein the indicator reagent zone includes a reagent capable, directly or indirectly, of immobilizing an enzyme-labelled reagent in an amount dependent upon the assay result, characterized in that the developing solution includes a signal producing substrate for the enzyme. The substrate moves slower through the absorbent material than the enzyme-labelled reagent or any compound of the enzyme-labelled reagent formed in the assay. The absorbent material is suitably in the form of an elongate strip provided with transverse reagent zones. The device is useful form performing immunoassays including immunometric assays and dual analyte assays.

Abstract: An analytical test device useful for example in pregnancy testing, includes a hollow casing (500) constructed of moisture-impervious solid material, such as plastics materials, containing a dry porous carrier (510) which communicates indirectly with the exterior of the casing via a bibulous sample receiving member (506) which protrudes from the casing such that a liquid test sample can be applied to the receiving member and permeate therefrom to the porous carrier, the carrier containing in a first zone a labelled specific binding reagent is freely mobile within the porous carrier when in the moist state, wherein the mobility is facilitated by a material comprising sugar, in a amount effective to reduce interaction between the test strip and the labelled reagent, and in a second zone spatially distinct from the first zone unlabeled specific binding reagent for the same analyte which unlabelled reagent is permanently immobilized on the carrier material and is therefore not mobile in the moist state, the two zo

Abstract: Immunoassay methods and reagents for the specific quantification of thyroxine in a test sample are disclosed employing antibodies prepared with thyroxine derivatives of the formula: ##STR1## wherein P is an immunogenic carrier material and X is a linking moiety. The present invention also describes the synthesis of unique labelled reagent of the formula: ##STR2## wherein Q is a detectable moiety and W is a linking moiety, preferably fluorescein or a fluorescein derivative.

Abstract: A method is provided for measuring the activity of cholesteryl ester transfer protein or MTP. The method comprises the steps of: adding a prepared emulsion particle to a buffer to form a buffered solution simulating physiological conditions, adding an emulsion of lipid to the buffered solution of prepared sonicated particle, adding a source of CETP or MTP to the buffered solution, adding a compound to the buffered solution for the purpose of testing the compound's effect on the neutral lipid transfer protein (CETP or MTP) activity, incubating the buffered mixture, reading the fluorescence of the solution, and calculating the effect of the compound on the emission spectra of the transfer label so transfer activity can than be accurately determined. A device that determines the activity of CETP or MTP by the use of a newly synthesized donor particle without regard to the presence of colored or otherwise interfering factors.

Abstract: A method and diagnostic kit is provided for diagnosing responsiveness to a hormone in a human subject that includes determining the amount of glucose utilized by a sample taken from the subject in the presence of the hormone. The sample taken from the subject may include body fluid or body tissue such as blood or skin. The glucose utilized in the test may be labelled for example, with a radioactive label. The diagnostic test may be used to determine responsiveness to estrogen in a human subject prior to treatment with hormone replacement therapy.

Abstract: This invention is directed to the novel assay methods utilizing nucleophilic polysubstituted aryl acridinium ester conjugates as the tracers. Conjugates prepared by covalent coupling of novel nucleophilic polysubstituted aryl acridinium esters with biological compounds including small organic molecules such as Vitamin B12, folate, cortisol, estradiol, and thromboxane B2, were found useful in the development of highly sensitive assays for the analytes of diagnostic interest.

Abstract: The invention is directed to an immunoassay for a thyronine derivative comprising:A. contacting a liquid sample, containing a thyronine derivative, with a labeled thyronine hapten analogue of the derivative in the presence of antibodies for the thyronine derivative under conditions that promote the formation of antibody-thyronine immunocomplexes; andB. determining the bound or unbound quantity of the thyronine derivative in the liquid; characterized in that the labeled thyronine derivative comprises:(i) a label, of the type used in immunoassays, having an amine or sulfhydyl group;(ii) a thyronine nucleus and(iii) a linking chain linking the label to the thyronine nucleus.

Abstract: Assay for detecting the amount or presence of target ligand in a sample. The assay includes a ligand analogue conjugate having a linkage site and a binding site, a ligand receptor, and a sample. The assay includes the steps of providing at least one crosstalk inhibitor. This inhibitor, under assay conditions, competes with the linkage site of the ligand analogue conjugate for binding to the ligand receptor, and does not compete with the binding site of the ligand analogue conjugate for binding to the ligand receptor. In the invention, the assay is performed for the target ligand in the presence of a sufficient amount of the crosstalk inhibitor to reduce the amount of binding of the linkage site of the ligand analogue conjugate to the ligand receptor. The invention also features a method for identifying crosstalk inhibitors, and the crosstalk inhibitors themselves.

Abstract: The present invention relates to immunoassay methods for detecting and measuring the amount of an analyte in a sample by means of generic anti-hapten antibodies. Also disclosed are multi-analyte immunoassay methods. Reagents, devices, and kits using the anti-hapten antibodies are also disclosed. The present invention also relates to immunoassay methods for detecting and measuring the amount of an analyte in a sample by means of a dual antibody format.The present invention also relates to dyed erythrocytes, preferably fixed, which are coated with antibodies. Also disclosed is the use of these dyed erythrocytes in agglutination assays to detect and measure the presence of an analyte in a sample. The analyte can be a hapten, an antigen, or an antibody. Also included are agglutination assays, compositions and kits using these dyed and coated erythrocytes.

Abstract: Antibodies against highly conserved amino acid sequences of immunogenic substances, a process for the preparation of these antibodies and the use thereof in immunoassays.The invention relates to antibodies which are obtained by immunization with a peptide fragment which represents a highly conserved amino acid sequence of a native protein. The antibodies according to the invention can be used for the preparation of immunoassays, in particular for the preparation of assays for the determination of genetically engineered products such as insulin which arise as sparingly soluble inclusion bodies in microorganisms. The invention particularly relates to a multispecies insulin assay in the form of an RIA.

Abstract: A prenatal screening test for risk of Down's Syndrome in a foetus, which is carried out on a maternal blood sample before the beginning of the third trimester of pregnancy, by assaying the sample for a metabolite of feto-placental activity which is affected by the presence of Down's Syndrome, selected from unconjugated oestriol; progesterone; 16-alpha-hydroxy-dehydroepiandrosterone sulphate (16-alpha-hydroxy-DHEAS); and dehydroepiandrosterone sulphate (DHEAS). An additional assay for alpha-fetroprotein and/or human chorionic gonadotrophin may be included.

Abstract: A hybridoma capable of producing monoclonal antibody for recognizing hCG-.beta. core region and hCG-.beta. subunit, which is obtained by cell fusion of an antibody producing cell of a mammal immunized with hCG-.beta. subunit and a lymphoid cell line, and the monoclonal antibody are disclosed. The monoclonal antibody can be used in an immunochemical determination method useful for diagnosis of cancers.

Abstract: Assay reagents, devices, methods and kits used in the analysis of low molecular weight analytes which by themselves are too small or unable to bind to two specific binding members at the same time. The invention involves the use of an analyte-substitute reagent (ASR) comprising at least two components, the first of which is identical to or an analog of the analyte to be determined, while the second is an unrelated ligand for which an antibody or other specific binding member can be obtained or produced.

Abstract: A device for performing an enzyme-labelled binding assay comprises an absorbent material and a developing solution, wherein the absorbent material is provided with a plurality of reagent zones including an indicator reagent zone, and is capable of transporting the developing solution by capillary action sequentially through each reagent zone, and wherein the indicator reagent zone includes a reagent capable, directly or indirectly, of immobilising an enzyme-labelled reagent in an amount dependent upon the assay result, characterised in that the developing solution includes a signal producing substrate for the enzyme. The substrate moves slower through the absorbent material than the enzyme-labelled reagent or any compound of the enzyme-labelled reagent formed in the assay. The absorbent material is suitably in the form of an elongate strip provided with transverse reagent zones. The device is useful for performing immunoassays including immunometric assays and dual analyte assays.

Abstract: The invention relates to a process for the immunometric determination of an antigen or hapten.According to this process, contacting takes place (FIG. 1A) between the antigen or hapten (3) to be determined and the antibodies (2) fixed to a solid phase in order to immunologically bond the antigen or hapten with the antibody. This is followed (FIG. 1B) by immobilizing the antigen or hapten (3) by a covalent bond (4) to the solid phase (1) whilst releasing its epitope (FIG. 1C). This is followed by the contacting thereof (FIG. 1D) with labelled antibodies (5) and determination takes place (FIG. 1E) of the quantity of fixed labelled antibodies in order to deduce therefrom the initial hapten or antigen concentration.As a result of this stage of immobilizing and releasing the epitope, a high sensitivity is obtained using a single antibody.

Abstract: A phosphorescence assay system. The phosphorescent label for immunoassays is palladium (II) octaethylporphine alphaisothiocyanate. The labeling agent has a Stokes shift of not less than 150 nanometers. Method for preparing the palladium (II) phosphorescent label is also shown.

Abstract: A method of determining free analyte level in a sample containing the analyte in free and bound portions is accomplished in sequential steps as follows. The sample is combined with a known first liquid volume containing soluble anti-analyte receptor in excess of the free analyte in the sample. The resultant mixture is incubated for a period of time sufficient to allow the binding reaction of the free analyte with the anti-analyte receptor to reach substantial completion to form a first incubation mixture. A known second liquid volume is added thereafter which contains soluble conjugate sufficient to reduce the sample proportion in the resultant mixture to no greater than 10% v/v, with the conjugate comprising a labeled analyte or labeled analog thereof, to allow the conjugate to bind with the anti-analyte receptor not bound in the first incubation mixture to form a second incubation mixture.

Abstract: A method of predicting ovulation and a test kit is described which allows one to accurately predict the time of ovulation in an animal in advance thus permitting the highest rate of pregnancy to be achieved and at the same time minimising embryonic death. Also described is a test kit for detecting and quantifying a given reproductive hormone and a method of optimising fertility in animals.

Abstract: A reagent for use in an immunoassay for measuring haptens, antigens or antibodies by means of a competitive binding method, which comprises a combination of an antibody and a labelled hapten or a labelled antigen or a combination of a hapten or an antigen and a labelled antibody, wherein the antibody and the labelled hapten or the labelled antigen in one combination or the hapten or the antigen and the labelled antibody in another combination are capable of undergoing reversible binding, and a device for use in an immunoassay wherein the reagent of the present invention is included in a single container.An immunoassay can be performed in a short time by the use of the immunoassay device of the present invention.

Abstract: A kit for use in determining the dosages and administering testosterone for the treatment of hair loss and disorders involving the lubricating function of the skin.

Abstract: A novel bidentate conjugate has two different chemical moieties, or bidentate members, attached through an adequate spacer moiety. Each bidentate member acts as a small molecule ligand and is capable of specifically binding to a different macromolecular substance. The bidentate members are relatively small molecules, usually less than about 7,000 Daltons in size. The spacer moiety is selected so that both bidentate members can simultaneously bind to their respective specific binding partners. Where the specific binding partners are multivalent, large complexes can be formed. The formation of these complexes can be inhibited by the presence of an unconjugated monovalent bidentate member, such as free analyte from a test sample. The bidentate is of particular use in turbidimetric or nephelometric inhibition immunoassay procedures.

Abstract: The present invention is an in-vitro blood assay method for determining the past and/or present use of exogenous erythropoietin by a living subject. The blood assay method detects, identifies, and determines the consequences of using an exogenous erythropoietin to generate an increase in red blood cell production in the living subject and provides a methodology by which to detect and determine both surreptitious as well as authorized therapeutic uses and applications of erythropoietin.

Abstract: A radioimmunoassay which comprises the steps of reacting a first antibody (A) on an insoluble solid, which is specific for an antigen (B); an antigen (B); and a second antibody (C) derived from an animal different from that of the first antibody (A), which binds to the antigen (B) under conditions that the concentration of the second antibody (C) is higher than the dissociation constant between the second antibody (C) and the antigen (B) to obtain an immune complex (D); reacting the immune complex (D) with a radiolabeled probe (E) and then measuring the radioactivity of the solid precipitate or the reaction mixture, to measure the quantity of antigen (B). The method provides an assay with high sensitivity which does not depend on the sensitivity of the second antibody to be used.

Abstract: Myo-inositol in a specimen is assayed by reacting a specimen containing myo-inositol with:a) myo-inositol dehydrogenase using a thio-NADP group or thio-NAD group and an NADP group or NAD group as coenzymes, and which catalyzes a reversible reaction forming myo-inosose from myo-inositol,b ) A.sub.1 andc) B.sub.1to effect a cycling reaction ##STR1## wherein A.sub.1 is a thio-NADP group, thio-NAD group, NADP group or NAD group, A.sub.2 is a reduced form of A.sub.1, when A.sub.1 is a thio-NADP group or thio-NAD group, B.sub.1 is a reduced NADP group or reduced NAD group and when A.sub.1 is an NADP group or NAD group, B.sub.1 is a reduced thio-NADP group or reduced thio-NAD group, and wherein B.sub.2 is an oxidized form of B.sub.1. The change in the amount of A.sub.2 generated or B.sub.1 consumed by the cycling reaction is measured to perform the assay. A composition for performing the assay comprises the above myo-inositol dehydrogenase, as well as the above components A.sub.1 and B.sub.1.

Abstract: In one aspect, a kit for the semi-quantitative measurement, in a liquid sample, by competitive immunoassay, of a first member of a specific binding pair, the kit including a solid support bearinga reference area which provides a detectable signal in the immunoassay, anda first and a second test area exposed to contact the sample, each test area containing a different amount of second or first member of the specific binding pair,whereby the intensity of the detectable signal from the reference area can be compared with the intensity of any detectable signals from the first and second test areas in the presence of an unknown quantity of the first member in the sample.

Abstract: A method is described for measuring the amount of analyte present in a sample containing the analyte using a homogeneous amperometric immunoassay. The analyte is chemically bonded to a suitable carrier molecule, which is also chemically bonded to an electroactive molecule. The electroactive molecule, such as ferrocene carboxylic acid, contains a redox center which is capable of transferring a charge to an electrode. A preferred carrier molecule is bovine serum albumin (BSA), while suitable analytes include digoxin, theophylline and HCG. The immunoassay is conveniently performed by applying a voltage to a set of electrodes.

Abstract: The present invention relates to the measurement of estradiol using competitive immunoassay methods. The inventors unexpectedly discovered that estrone and its derivatives conjugated to a label is a particularly effective tracer when used in conjunction with estradiol specific antibodies to determine estradiol levels in fluid samples. The present invention also utilizes 5.alpha.-dihydrotestosterone to enhance the assay performance.

Abstract: Assay reagents, devices, methods and kits used in the analysis of low molecular weight analytes which by themselves are too small or unable to bind to two specific binding members at the same time. The invention involves the use of an analyte-substitute reagent (ASR) comprising at least two components, the first of which is identical to or an analog of the analyte to be determined, while the second is an unrelated ligand for which an antibody or other specific binding member can be obtained or produced.

Abstract: The precision of identification of analyte composition in a sample, where the possible analytes cross-react with specific binding reagents, is enhanced by applying pattern recognition techniques. Samples to be tested are reacted with a panel of specific binding reagents reactive with the set of analytes to be tested to obtain a pattern of reactivity with respect to each analyte at a given concentration. This results in a databank of "CRIM profiles" for known concentrations of each analyte. This databank is stored in a computationally accessible form, which then can be matched against CRIM patterns obtained by testing unknown samples. In one embodiment, each CRIM pattern obtained is plotted as a single point in n-dimensional space, wherein n represents the number of specific binding reagents in the panel.

Abstract: A method and apparatus for determining if a pregnant woman is at significant risk of carrying a fetus with Down syndrome, The method comprises measuring the pregnant woman's maternal blood levels of the free beta subunit of human chorionic gonadotropin. The level of free beta subunit of human chorionic gonadotropin individually or with other markers may be compared to reference data. A computerized apparatus for making the determination preferably using a probability density function generated from a set of reference data by a linear discriminant analysis procedure is disclosed.

Abstract: Homogeneous membranes permeable to oxygen and glucose composed of hydrophilic polyurethanes that are capable of absorbing from 10 to 50% of their dry weight of water. Variations in the composition of the hydrophilic polyurethanes make possible the fabrication of membranes in which the ratios of the diffusion coefficients of oxygen to glucose can be varied over a wide range. These membranes can be used in the fabrication of an electrochemical glucose sensor intended for use in vivo as an aid in the treatment of diabetes mellitus.

Abstract: The present invention relates to assay techniques for detection of ligands in solution and to means for putting such techniques into effect. In particular it relates to an improved assay technique which provides a liquid calibrator for use in standard assays in circumstances where the ligand itself is rare, expensive, or difficult to prepare in a sufficiently pure or quantifiable form.

Abstract: A blood serum sample useful as a calibration baseline comprising a natural blood matrix is disclosed. This serum sample contains less than an HPLC-detectable amount of cortisol. Also disclosed is a serum sample containing less than HPLC-detectable amounts of cortisone and corticosterone and less than RIA-detectable amounts of testosterone, androstenedione, progesterone, DHEA sulfate and 17-OH progesterone. A method of preparing such a serum sample is also disclosed.

Abstract: The present invention relates to a homogeneous process for the detection and/or determination of an analyte in a medium in which it may be present, by disclosing the reaction product of the analyte and a corresponding receptor, process consisting in: 1) adding to said medium a first reagent consisting of a receptor for the said analyte; 2) adding a second reagent consisting of at least one of the components of the reaction product of the analyte and at least one of its receptors; one of the two reagents being coupled with a luminescent compound and the other reagent possessing a heavy atom or units containing a heavy atom; 3) incubating the medium after addition of each reagent or after the addition of both reagents; 4) exciting the resulting medium and 5) measuring at equilibrium or during the kinetics, the signal emitted by the luminescent compound, said signal being modulated by the heavy atom effect.

Abstract: The present invention relates to immunoassay methods for detecting and measuring the amount of an analyte in a sample by means of generic anti-hapten antibodies. Also disclosed are multi-analyte immunoassay methods. Reagents, devices, and kits using the anti-hapten antibodies are also disclosed. The present invention also relates to dyed erythrocytes, preferably fixed, which are coated with antibodies. Also disclosed is the use of these dyed erythrocytes in agglutination assays to detect and measure the presence of an analyte in a sample. The analyte can be a hapten, an antigen, or an antibody. Also included are agglutination assays, compositions and kits using these dyed and coated erythrocytes.

Abstract: Specific binding methods are used for diagnostic assays and purification separations whereby the specific binding capture reagent is prepared from copolymers having highly reactive carboxy groups. These groups are extended from the polymer surface with a linking group having from 8 to 50 atoms in the chain and two or more alkylene, arylene, alkylenearylene or arylenealkylene groups. To these reactive groups is attached a biologically active substance such as a protein or oligonucleotide which then participates in the diagnostic assays or purification separation methods.

Abstract: The present invention relates to a method for detecting fetal Down syndrome (Trisomy 21), trisomy 13, trisomy 18 and other chromosomal anomalies during prenatal screening by analyzing a dried blood sample from a pregnant woman. More particularly the present invention relates to a method for improving detection efficiency in screening for the anomalies by measuring the amount of the free beta human chorionic gonadotropin (HCG) and nicked or fragmented or aberrant forms of free beta (HCG), all of which are referenced throughout this application as free beta (HCG) in dried blood samples from pregnant women.

Abstract: A stabilized prolactin calibrator is disclosed. The calibrator has a pH from about 5.5 to about 9.0, and contains prolactin in a 0.01 M to 0.2 M matrix of tris-(hydroxymethyl)aminomethane which additionally contains about 0.3 to 4 percent of bovine serum albumin, about 0.05 to 0.2 percent of sodium azide and from about 0.01 to about 0.2 mole/liter NaCl.

Abstract: The invention concerns a method for the determination of a partner in an immunological reaction based on an immunoassay in which one of the reaction partners is present in a solid phase, wherein a polyethylene oxidepolypropylene oxide block copolymer having the formula I ##STR1## is used as the surface-active agent in which a can have a value between 40 and 150 and b a value between 10 and 50, which is characterized in that a hydrophilic block copolymer composition having the formula I is used which in a 1 % aqueous solution (weight/volume) has a surface tension of at least 45 mN/m and in which the average molar ratio of ethylene oxide groups to propylene oxide groups (2a/b) in the composition is at least 5.8. In addition the invention comprises a reagent for carrying out the above method.

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: A laser magnetic immunoassay (LMIA) technique is presented which combines the high detection sensitivity of the radioimmunoassay (RIA) technique with the simplicity of particle agglutination (PA) technique. The LMIA technique dispenses with the separation step of bound and free species (B/F separation), yet provides detectivity of the order of picogram of viral species per milliliter of analyte solution. The procedure includes of the steps of: preparing a superparamagnetic-labeled body of antigen or antibody; subjecting a specimen sample and the magnetic-labeled body to a specific immunoreaction to produce a reacted body; subjecting the reacted body containing both bound and free species to a spot magnetic field gradient; irradiating the spot with a laser beam; measuring the intensity of the outgoing light from the spot; and making a quantitative determination of the virus according to the time difference in the outgoing light signals generated by bound and free species.

Abstract: A laser magnetic immunoassay (LMIA) method which enables detection of less than picograms of target analyte in milliliter of analyte solution. The method involves the steps of: affixing an antibody or antigen on the surface of non-magnetic carrier particles; immunoreacting the affixed antibody or antigen to capture a target analyte contained in a specimen; preparing magnetic labeled microparticles treated so as to bind with the target analyte; reacting the labeled complex to sandwich the target analyte between the magnetic particles and the non-magnetic carrier particles; separating the free species from the bound species by centrifugation; dispersing the precipitated solid to make an analyte solution; applying a spot magnetic field gradient on the analyte solution and irradiating a selected spot with a laser beam; and analyzing the resulting interference patterns to quantitatively determine the quantity of target analyte.

Abstract: An in-situ laser magnetic immunoassay ("LMIA") method which eliminates the step of B/F separation generally required in the labeling method of immunoassays. The laser magnetic immunoassay permits a quantitative determination of a target immunological substance, for example, an antigen, an antibody, lymphocytes, viruses, tumorous cells and infections cells, in an analyte solution containing both bound and free species. A transitory increase in the magnetophoretic scattering of laser beam is observed when the analyte solution contains magnetic-labeled, bound target analyte, while no such increase is observed in a control test solution, containing only the relevant reagents. A magnetophoretic LMIA apparatus is provided which includes a magnetic gradient generating device which forms an integral part of the in-situ LMIA.

Abstract: Methods for determining the presence of a first ligand, preferably a hapten, in a sample suspected to contain the first ligand are provided, along with reagent systems and apparatus suitable for performing the methods. The methods depend upon a color visualization indicating the presence or absence of the first ligand in the sample. Preferred methods comprise contacting the sample with a reagent system which comprises: (1) colored particles which bear on their surface a second ligand which may be the same as or different than the first ligand; and (2) an amount of a receptor which is specific for the first ligand and the second ligand, wherein the amount is sufficient to stabilize the particles. The methods further comprise passing the contacted sample and reagent system through a filter, and then analyzing the color of the filtrate. The presence of ligand in the sample is established where the color of the filtrate is substantially different from the color of the ligand-bearing particles.

Abstract: A methodology is presented which relates in general to fluorescence polarization immunoassays (FPIA) and modifications of current processes wherein detection and quantification of several commonly abused or therapeutic drugs in a single biological fluid sample are determined utilizing manual or current software or related equipment to allow the sequential and simultaneous performance of more than one FPIA assay. The methodology involves combining the reagents either separately or pre-mixed, for multiple assays in a single reagent package, these reagents being used to assay quantitative amounts of each of the assay analytes in a sequential step manner. The assay being performed by mixing the sample with a combination reagent and then initiating a specific reaction for each of the separate analytes by sequentially adding a specific reagent, i.e.

Abstract: A method for immunochemical determination of a hapten in a sample is disclosed, in which(A) a high-molecular compound to which the hapten is bound (reagent A),(B) insoluble carrier particles carrying thereon an antibody to the hapten (reagent B), and(C) magnetic substance-containing insoluble carrier particles carrying thereon an antibody to an antigenic determinant in the high-molecular compound and different from the hapten (reagent C),are used. These three reagents are dispersed in the sample, then, a magnetic field is applied to separate from the reaction mixture unreacted reagent (C) and agglutinated particles formed from the reagent (B) and the reagent (C) through the reagent (A). The amount of the reagent (B) remaining dispersed in the reaction mixture is measured, thereby determining the extent of competitive inhibition to the agglutination of the reagent (B) and the reagent (C) through the reagent (A) by the reaction between the hapten in the sample and the reagent (B).

Abstract: A method is described for measuring the amount of analyte present in a sample containing the analyte using a homogeneous amperometric immunoassay. The analyte is covalently bonded to a suitable carrier molecule, which is also covalently bonded to an electroactive molecule. The electroactive molecule, such as ferrocene carboxylic acid, contains a redox center which is capable of transferring a charge to an electrode. A preferred carrier molecule is bovine serum albumin (BSA), while suitable analytes include digoxin, theophylline and HCG. The immunoassay is conveniently performed by applying a voltage to a set of electrodes.

Abstract: A method and kit are provided for determining levels in a biological sample of free IGF-I, IGF-II, or GH ligand that is normally associated in the sample with a binding protein. This method involves contacting the body fluid with an immobilized unlabeled capture reagent and incubating at 4.degree.-10.degree. C. for no greater than about 4 hours to bind the free ligand contained in the body fluid; separating the fluid from the immobilized capture reagent; and measuring the level of free ligand now bound to the capture reagent. This method is particularly useful to determine levels of free IGF-I in serum or plasma.

Abstract: A novel bidentate conjugate has two different chemical moieties, or bidentate members, attached through an adequate spacer moiety. Each bidentate member acts as a small molecule ligand and is capable of specifically binding to a different macromolecular substance. The bidentate members are relatively small molecules, usually less than about 7,000 Daltons in size. The spacer moiety is selected so that both bidentate members can simultaneously bind to their respective specific binding partners. Where the specific binding partners are multivalent, large complexes can be formed. The formation of these complexes can be inhibited by the presence of an unconjugated monovalent bidentate member, such as free analyte from a test sample. The bidentate is of particular use in turbidimetric or nephelometric inhibition immunoassay procedures.