Abstract: An improved process for the preparation of antigenic protein conjugates is provided. The conjugates preferably are formed through reaction with one or more free sulfhydryl groups in the antigenic protein. The process of the present invention preferably employs a trialkylphosphine as the reducing agent and allows for reduction of disulfide bonds in the antigenic protein and conjugation with a conjugate moiety, preferably in a single reaction vessel (i.e. “in situ”) because the process optimally does not require the removal of the reducing agent before subsequent addition of the sulfhydryl reactive agent. Antigenic protein conjugates prepared by the in situ process and their use in diagnostic immunoassays are also provided.

Abstract: An improved process for the preparation of antigenic protein conjugates is provided. The conjugates preferably are formed through reaction with one or more free sulfhydryl groups in the antigenic protein. The process of the present invention preferably employs a trialkylphosphine as the reducing agent and allows for reduction of disulfide bonds in the antigenic protein and conjugation with a conjugate moiety, preferably in a single reaction vessel (i.e. “in situ”) because the process optimally does not require the removal of the reducing agent before subsequent addition of the sulfhydryl reactive agent. Antigenic protein conjugates prepared by the in situ process and their use in diagnostic immunoassays are also provided.