Immunological test method

Abstract

A test method for determining the presence or absence of an antigen or antibody analyte in a sample. The sample is first reacted in a reaction vessel with magnetic carrier particles having immobilized thereon a substance which specifically binds to said analyte, thereby forming bound and unbound magnetic carrier particles. The bound and unbound magnetic carrier particles are then precipitated on a flat and substantially horizontal inside wall surface of said reaction vessel with a magnet provided outside the reaction vessel, such that a gradient magnetic field is formed in a plane perpendicular to a direction in which the bound and unbound magnetic particles are precipitated, thereby forming a precipitation image on the wall surface. Finally, the presence or absence of the analyte is determined by the shape of the precipitation image. The gradient magnetic field is formed by placing the magnet outside said reaction vessel such that the distance between the wall surface of the reaction vessel on which the precipitation image is formed and the surface of the magnet opposing the wall surface is gradually increased, thereby forming an effective angle between the magnet and the wall surface. The precipitation image is formed independently of the shape of the reaction vessel. When the wall surface of the vessel is flat, it is very easy to stably maintain the precipitation image after its formation.

Dependencies are inferred from the claim text.