An immunochemical method is provided for the detection and determination of an analyte. The zeta potential of a latex-particle loaded with an immunologically active substance is measured before and after bringing the loaded latex-particle into contact with an analyte. The difference in zeta potential is correlated with changes of zeta potential for known concentrations of the analyte in order to determine the presence and amount of the analyte.

A portable pathogen detection system that accomplishes on-site multiplex detection of targets in biological samples. The system includes: microbead specific reagents, incubation/mixing chambers, a disposable microbead capture substrate, and an optical measurement and decoding arrangement. The basis of this system is a highly flexible Liquid Array that utilizes optically encoded microbeads as the templates for biological assays. Target biological samples are optically labeled and captured on the microbeads, which are in turn captured on an ordered array or disordered array disposable capture substrate and then optically read.

A dual particle immunoassay method and kit for detecting analyte in a sample in which the sample to be analyzed, a binding molecule specific for the analyte, and a particle coated with the analyte to be detected or coated with a second binding molecule are reacted and applied to a porous membrane. The competitive immunoassay utilizes an analyte-coated particle, whereas the sandwich immunoassay employs a second binding molecule-coated particle. All of the reagents except for the coated particle are able to pass through the porous membrane. Detectable particles coated with a binding substance that binds to the binding molecule, such as protein A protein G, second antibody reactive to the binding molecule, or a small synthetic affinity ligand, are reacted with coated particles retained on the membrane surface. The detectable particles will pass through the membrane if not complexed with the coated particle. In the competitive immunoassay, detectable particles bind to binding molecules that complex with the analyte-coated particles in the absence of analyte and are detected. In the sandwich immunoassay, detectable particles bind to binding molecules that are attached to the coated particle in the presence of analyte and are detected.

On a slab-like board formed of a transparent material is closely attached a wedge-shaped transparent cover member provided with a recess in a central inner portion, thereby to form a clearance. The height of the clearance between the recess and the board is configured to decrease continuously or in steps. When an immunological active substance such as a monoclonal antibody is caused to sensitize carrier particles F, and a reagent having the carrier particles F dispersed into a liquid medium mainly composed of the water is mixed with a specimen, the reaction will occur in which the flocculate is formed from plural carrier particles. When this reaction liquid is poured into the clearance through the opening, the reaction liquid penetrates in the direction having a narrower vertical spacing due to surface tension. A single carrier particle unflocculated can move deep within the recess because it is small in diameter, but the flocculate G is trapped on its way and can not move because of its size.

The invention is a rapid, continuous test for glycated hemoglobin using a non-equilibrium affinity binding method. Agarose beads derivatized with 3-aminophenylboronic acid specifically bind glycated hemoglobin. This solid phase is incorporated into a sample processor card, modified to mix and to separate the test solution from the solid phase prior to absorbance readings. Two absorbance readings are made on the test solution, one immediately after mixing the reagent/diluent with the specimen, and one after a significant amount of binding has occurred. A linear correlation between total glycated hemoglobin and hemoglobin A.sub.1c permits standardization and reporting of units equivalent to % hemoglobin A.sub.1c. Stable glycated hemoglobin solutions for use as standards in the assay, and a method for preparing the standards are also disclosed.