Highly sensitive monoclonal antibody residual detection assay

A method for detecting an antibody product, or fragment thereof, the method comprising:

• (a) contacting a test sample suspected of containing the antibody product or fragment thereof with a substrate comprising a mixture of five or more distinct classes of capture antibodies or antigen binding fragments thereof so as to form at least one capture antibody-antibody product complex;
• wherein the five or more distinct classes of capture antibodies or antigen binding fragments thereof are:
• anti-human IgG heavy and light chains (H+L), anti-human IgG F(ab') 2, anti-human IgG lambda, anti-human IgG kappa, and anti-mouse IgG (H+L) antibodies;
• and wherein the anti-human IgG (H+L), anti-human IgG F(ab′)2, anti-human IgG lambda, anti-human IgG kappa, and anti-mouse IgG (H+L) antibodies are present in the mixture in a ratio of 1:2:16:8:8;
• (b) detecting the at least one capture antibody-antibody product complex using a composition capable of detecting the at least one capture antibody-antibody product complex, wherein detection of the at least one capture antibody-antibody product antigen-complex is indicative of the presence of the antibody product, or fragment thereof, in the test sample.