An immunoassay incubation device is employed for detecting the presence of specific analytes in solid and semisolid compositions using solid phase immunoassay methods. Analysis of such compositions by solid phase immunoassay first requires that soluble or particulate analytes be extracted from the sample composition. A representative example of such composition is fecal material. The immunoassay incubation device includes a vessel for homogenizing the sample composition. The device also includes a solid phase assay member immunologically sensitized for detecting particular analytes. After the sample composition is homogenized, the assay member is incubated in an incubation chamber which is immersed into the homogenate within the homogenization vessel. The incubation chamber includes a screen which screens out unextracted components from the homogenate while passing extracted components. The invention discloses that contact with unextracted components from such compositions can degrade the accuracy of solid phase immunoassays.