Antibodies generated from ascites fluid and serum are often supplied as crude formulations. Both ascites fluid and serum contain many substances that interfere with antibody labeling reactions. Successful labeling therefore requires antibodies to be purified prior to labeling. The AbSelect Serum system is a fast and simple method to purify antibodies from these types of media. AbSelect Serum is prepared by coupling highly purified protein A to agarose beads which can be used to purify IgG fractions from ascites fluid and serum. The method involves the capture of the antibody on the AbSelect Serum resin and the removal of unwanted substances using a simple wash procedure. The purified product is then eluted and neutralized.