A recently developed shallow-well microtiter plate, made from a specially formulated polymer that binds proteins, peptides and nucleic acids rapidly and efficiently, has been investigated for use in solid-phase immunoassays as well as for protein and phospholipid assays. The assay uses quantitation of the color intensity of a dye on the solid phase by means of a simple desk-top scanner coupled to a computer which allows the gray-scale density of the color to be easily and accurately measured. Consequently, this approach is independent of the absorption spectrum of the dye used.