Beckman Instruments, Inc.

Ker-Kong Tung

Kenneth J Pierre

Henriette Nadj

Linda K Cragle

Shih-Yun Lee

Paul C Harris

Morton A Vodian

Frederick W Rood, Jr

A method for obtaining an actual linear standard curve in a sandwich type of immunoassay where a first antibody bound to an insoluble support and a second unbound labelled antibody complex with the antigen contained in a test sample to form an insoluble antibody:antigen:labelled antibody complex which is then detected. Unbound unlabelled first antibody and/or unbound unlabelled second antibody are added to the reaction mixture to divert excess antigen away from the desired end-product complex, thus rendering the antigen of interest the rate-limiting factor in the overall immunoreaction. This results in a pseudo first-order reaction which produces an actual linear standard curve.

Method to achieve a linear standard curve in a sandwich immunoassay

An immunoassay for assaying an antigenic substance (Ag) in a fluid. The immunoassay is the type which comprises contacting the fluid with at least one first entity selected from a group consisting of an antibody (Ab) to the Ag, a soluble, labeled antibody (L-Ab.sub.a) to the Ag, and an antibody (Ab.sub.b) to the Ag bound to a solid support (SC). The immunoassay is characterized in that the fluid is contacted with at least one additional entity selected from a group consisting of at least one different type of soluble, labeled antibody (L-Ab.sub.c) to the Ag, at least one different type of antibody (Ab.sub.d) bound to a solid carrier (SC.sub.1), and at least one different type of antibody (Ab.sub.e) to the Ag. The SC.sub.1 is selected from a group consisting of SC, at least one different solid carrier (SC.sub.2), and mixtures thereof (SC and SC.sub.2). Each type of L-Ab.sub.c, Ab.sub.d -SC.sub.1, and Ab.sub.e has a lower average affinity constant (K) for Ag than each respective K of L-Ab.sub.a, Ab.sub.b -SC and Ab.sub. e ; and the additional entity is present in an amount sufficient to avoid a hook effect. Also, a reagent of the type comprising at least one first entity selected from a group consisting of L-Ab.sub.a, Ab.sub.b -SC, and Ab. The reagent is characterized in that it further comprises at least one additional entity selected from a group consisting of at least one different type of L-Ab.sub.c and at least one different type of Ab.sub.d -SC.sub.1, and at least one different type of Ab.sub.e. Ab, L-Ab.sub.a, Ab.sub.b -SC, L-Ab.sub.c, Ab.sub.d -SC.sub.1, and Ab.sub.e are as defined above.

Immunoassays and kits for use therein which include low affinity

A direct particle agglutination immunoassay for assaying an antigenic substance (Ag) in a fluid. The immunoassay is the type which comprises:

Direct particle agglutination immunoassays avoiding false negatives at

A kinetic assay is provided for determining the acid phosphatase in an aqueous solution by measuring the amount of of reduced coenzyme produced. The assay is based on the following coupled reactions:

Kinetic assay for acid phosphotase and composition therefore

A kinetic assay is provided for determining the inorganic phosphate content in an aqueous solution by measuring the amount of reduced coenzyme produced. The assay is based on the following coupled reactions: I. maltose+PO.sub.4.sup.-3 maltose phosphorylase glucose+.beta.-D-glucose-1-phosphate; Ii. .beta.-d-glucose-1-phosphate .beta.-D-phosphoglucomutase glucose-6-phosphate; Iii. glucose-6-phosphate+NAD glucose-6-phosphate dehydrogenase NADH+6-phosphogluconate.

Kinetic assay for inorganic phosphates and composition therefore

The range of linearity of the kinetic method for the determination of glucose concentrations using a reagent of the type comprising a buffer, a pyridine coenzyme, and glucose dehydrogenase, is significantly increased when the buffer employed in the reagent has a pH of from about 7.9 to about 9.0.

Kinetic method for determination of glucose concentrations with glucose

A reagent system for beta-amylase assay comprising: A polysaccharide having glucose molecules primarily connected through alpha 1,4 linkages Phosphate ions Maltose phosphorylase A co-enzyme selected from a group consisting of beta-nicotinamide-adenine dinucleotide, beta-nicotinamide-adenine dinucleotide phosphate, and mixture thereof Glucose-6-phosphate dehydrogenase Beta-D-phosphoglucomutase Mutarotase.

Reagent system for beta-amylase assay

A kinetic assay is provided for measuring alpha-amylase content in aqueous solutions. The assay is based on the following reactions:

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Vista, CA, United States of America

Ker-Kong Tung