Abstract: Useful materials for diagnostic tests, affinity chromatography, enzymatic reactions and immunoassays are prepared by covalently attaching reactive compounds containing reactive amino or sulfhydryl groups to polymeric particles having pendant carboxyl groups on the outer surfaces. Such reactive compounds include biologically reactive species, such as enzymes, polypeptides and proteins. This attachment is carried out using carbamoylonium compounds which react with the carboxyl groups to form intermediate reactive groups which then react with the amino or sulfhydryl groups to form a covalent linkage between particle and reactive compound. A kit comprises polymeric particles having carboxyl groups on the outer surfaces, and a carbamoylonium compound.

Abstract: A method for attaching a reactive amine- or sulfhydryl-containing compound to polymeric particles using dication ether salts is disclosed.

Abstract: Hydrolyzable substrates comprise blocked moieties which, when cleaved from the substrate during hydrolysis, provide electron transfer agents. The released electron transfer agents can be recycled between a reductant and a reducible compound that upon reduction provides a detectable species. Alternatively, they can be recycled between an oxidant and an oxidizable compound that upon oxidation provides a detectable species. These substrates are useful in analytical compositions, elements and methods for the determination of hydrolytic analytes, such as hydrolytic enzymes or biological cells containing such enzymes.

Abstract: Hydrolyzable substrates comprise blocked dye moieties which, when cleaved from the substrate during hydrolysis, provide fluorescent dyes having maximum absorptions above about 530 nm and maximum emissions at least about 580 nm at physiological pH. These substrates can be used in analytical determinations of hydrolytic substances including hydrolytic enzymes or biological cells containing such enzymes.

Abstract: Certain substituted benzo- and naphthoquinone electron transfer agents are useful in analytical compositions, elements and methods, e.g. for determinations of living cells. These electron transfer agents are capable of being reduced by an analyte, and the reduced electron transfer agent, in turn, reduces another compound providing a detectable species (e.g. a dye). The reduction potential (E.sub.1/2) of the electron transfer agents useful inthis invention is in the range of from about -320 to about +400 mV as measured in an aqueous buffer solution at pH 7.