Abstract: A method of immunologically staining a formalin-fixed tissue preparation, which comprises (a) subjecting a formalin-fixed tissue preparation to microwave energy while the tissue preparation is submersed in water for a time sufficient to increase immunostaining efficiency; (b) removing the tissue preparation from the water and cooling; and (c) contacting the tissue preparation with an immunological staining reagent.

Abstract: An apparatus is provided for use in an immunoassay for the detection of a target analyte in a liquid sample, comprising a porous reactive filter, having an upper surface and a lower surface, to which is bound an antibody specific for the target antigen; a holder affixed to the porous filter, wherein the upper surface and lower surface of the reactive filter are accessible for passage of liquids through the reactive filter; an absorbent container capable of being detachably attached to the holder; and an absorbent material contained within the container so as to contact the lower surface of the porous filter when the absorbent container is attached to the holder. A prefilter assembly can optionally be attached to the holder so that the prefilter contacts the upper surface of the reactive filter.

Abstract: A stabilized phosphatase substrate composition is provided comprising an indoxl phosphate, a tetrazolium salt, and a water-soluble ferricyanide/ferrocyanide salt. When present as a solution, the composition also contains a buffer that produces a pH in a range of from about 8 to about 11.