Abstract: A method and assembly provided for the detection and determination of at least one ligand in a sample suspected of containing the ligand. The method includes providing in a hand-held assembly having a first chamber and a second chamber separated by a separation means which permits the passage therethrough of materials of a relatively small size while preventing the passage therethrough of materials of a relatively larger size; a suspension in the first chamber of an admixture of a binding partner for the ligand and a labeled component. The labeled component is selected from the group consisting of binding partner, compound which can bind to the binding partner, compound which can bind to the reaction product of the ligand and binding partner, and compound which can bind to the ligand. The sample suspected of containing the ligand is introduced to the first chamber.