Patent ID: 7722812

Claim:
A reaction disk for an automatic analyzer, comprising: a reaction disk body that is rotatable about a vertical axis; at least one separation cell; at least one determination cell, said at least one separation cell and said at least one determination cell being respectively arranged along a periphery of the reaction disk body located radially outward of said vertical axis, said at least one separation cell and said at least one determination cell being provided as discrete cell units which are independently separate from one another in said reaction disk body, at least a radially outward internal wall of each of said at least one separation cell and said at least one determination cell being maintained in a substantially parallel orientation with respect to said vertical axis when said reaction disk body is at rest and during rotation of said reaction disk body, supernatant separated by said centrifugal separation from the suspension contained in the separation cell being dispensable to the determination cell to allow analysis of a target substance in the supernatant; and said at least one separation cell having an internal structure defining an insoluble matter collection zone in a lower portion of said at least one separation cell and a supernatant separation zone in an upper portion of said at least one separation cell, a horizontal sectional area of the supernatant separation zone being greater than another horizontal sectional area corresponding to said insoluble matter collection zone and a horizontal shelf is formed at the boundary between said supernatant separation zone and said insoluble matter collection zone where a portion of said supernatant separation zone extends radially inward of the insoluble matter collection zone, said shelf is orthogonal to a radially inward vertical wall of said insoluble matter collection zone; and each said at least one separation cell including a lid being positioned to only partially cover each said at least one separation cell, said lid being disposed at a radially outward position of each said at least one separation cell directly over said horizontal sectional area corresponding to the insoluble matter collection zone, so as to leave an opening through which the supernatant is withdrawable from above said portion of said supernatant separation zone which extends radially inward of said insoluble matter collection zone, while concomitantly blocking flow of said suspension outward from said at least one separation cell during centrifugal separation.