Abstract: Detection of bindable substances such as antibodies and antigens using enzyme linked immunosorbent assays having particular utility in home diagnostic applications. The preferred implementation of the invention is characterized by the steps of admixing a sample suspected of containing the bindable substance to be detected with an antibody-enzyme conjugate, immersing an antibody coated solid support into the mixture and then exposing the coated support to an activated chromogenic solution. The conjugate for use in the home diagnostic assay is preferably contained within a lyophilized mixture. The lyophilized mixture contains components which preserve the antibody-conjugate's reactivity and immunologic binding specificity even if the lyophilized mixture had been subjected to hot, humid environmental conditions. Active components in the lyophilized mixture include polyethylene glycol, sugars, and surfactant.

Abstract: An assay employing two antibodies. A microporous carrier supports a plurality of layers, in which conjugates form between test antigens and antibodies. Quantitative results are obtained from an immobilized antibody within an indicating substrate.

Abstract: A chromogenic solution for enzyme immunoassay. A stabilizing agent is added to chromogenic solutions containing chromogen of the hydrogen donor type. The stabilizing agent is an alkylhydroxylamine, preferably N,N-diethylhydroxylamine. The N-N diethylhydroxylamine retards degradation of the solution of the chromogen in solvent and is particularly effective in retarding discoloration of a chromogen-solvent solution placed in storage over an extended period of time. The alkylhydroxylamine preferably in the form of N,N-diethylhydroxylamine has the additional property that it does not adversely affect the activity of enzymes employed in enzyme immunoassays. It also does not interfere with binding specificity or reactivity of antibodies.