| abstract |
An automated analytical apparatus by which homogeneous and heterogeneous analyses can be performed concurrently and on a random access basis includes a circular reaction tray (3) supporting a multiplicity of peripherally arranged reaction cuvettes, sample handling arrangement (4)for supporting samples to be analyzed and a reagent tray (73) supporting a plurality of liquid-reagent sources. The individual samples and liquid reagents are transferred, on a selective-random mode, by appropriate aspirating-dispensing apparatus (5,8) into reaction cuvettes on the reaction tray which are successively positioned at sample and reagent addition stations. The reaction tray is rotated from the reagent addition station to allow mixing and incubation of the reaction mixture and to position each cuvette at an analysis station (11). In the case of heterogeneous assays, magnetic particles are introduced into appropriate cuvettes at a magnetic particle suspension addition station. A particle wash station (9) is provided between the magnetic particle suspension addition station and the analysis station (11) whereat, after the reaction, the solid phase is washed in the reaction cuvette to remove unbound materials. Following such wash, substrate may be added (10) to the reaction cuvette for reaction with an enzyme solid phase and the magnetizable particles are resuspended. The reaction cuvette is then advanced to the analysis station, where the solid phase is withdrawn from the optical path and the appropriate optical readout of the liquid phase is effected. In respect of both heterogeneous and homogeneous assays, the rotational mode of the reaction tray is bidirectional, to provide multiple periodic readouts of each cuvette, to obtain data which is processed to provide the rate of the reaction. |