Abstract: An assay element for analyzing a charged analyte employs an immobilized receptor and a material having a net charge which is the same as that of the analyte. In a preferred embodiment, the analyte is an aminoglycoside and the material is a polymer having a net positive charge.

Abstract: An assay element for analyzing a charged analyte employs an immobilized receptor and a material having a net charge which is the same as that of the analyte.

Abstract: An immunoassay element comprising at least one layer containing a leuco dye coating composition comprising:______________________________________ Dry Weight Component Ratio (Range) ______________________________________ a) Triarylimidazole leuco dye 55-80 b) Antioxidant 7-40 c) Poly[poly(ethylene oxide)-block- 6-20 poly(propylene oxide)] nonionic block copolymer d) Alkylaryloxypoly(alkylene oxide) 1-16 nonionic surfactant ______________________________________

Abstract: A dry analytical element can be used to sensitively and rapidly detect a wide variety of specific binding ligands in either a competitive binding or sandwich assay format. The assays are carried out using a peroxidase-labeled immunoreactant. The peroxidase label is stabilized with a 4-hydroxy or 4-alkoxyarylacetamide which is located in one or more zones of the element. Not only is the label stabilized with the stabilizer, but the assay is more sensitive.

Abstract: Dry transparent analytical elements can be used to determine analytes which have been separated by electrically induced migration through a solid medium, e.g. by electrophoresis, or which are intracellular enzymes. The dry transparent element is placed on a plate containing the analytes, and kept there until the analytes have reacted to produce a non-diffusible detectable species solely in the element. The element is removed and the detectable species is evaluated therein. The elements contain a water-insoluble binder material having an interactive composition dispersed therein which reacts with analyte to produce the non-diffusible species. The same electrophoretic plate can be used to successively determine the same or a plurality of analytes since it is not altered or destroyed by contact with the dry element.

Abstract: An analytical element can be used for the determination of either creatinine or creatine or both. The element contains creatinine amidohydrolase, creatine amidinohydrolase and sarcosine oxidase, and a leuco dye which is capable of providing a detectable dye in the presence of hydrogen peroxide and a peroxidative substance. The creatine amidinohydrolase is present in a manner such that it is substantially inert to the leuco dye. The creatinine amidohydrolase is present in a rate limiting amount. By measuring the amount of dye formation at particular times during the assay, either or both of the analytes can be determined with the same element.