What is a specific antibody concentration?

For antibodies provided in a serum format (polyclonal) or not purified supernatant (monoclonal), the final concentration of specific antibody is not estimated. Instead of specific antibody concentration one has to use recommended dilution of an antibody in a given technique as a guideline.

Following antibody purification, also called affinity purification, (on Protein A or G), a total immunoglobulin fraction is obtained. The concentration of specific anti-target antibodies is not determined. Usually it varies from 0.5 to 5 % of a total immunoglobulin pool.

Specific antibody concentration can be estimated following affinity purification on an antigen (peptide or protein) coupled to an appropriate matrix. In such cases, the concentration of specific antibody is provided on a tube or can be calculated following reconstitution of a known amount of purified antibody. For example, 50 µg in 50 µl of deionized water will give specific antibody concentration of 1 µg/µl.