Normal horse serum lipid extracted and dialyzed against 10 mM sodium phosphate, 0.15 M sodium chloride, pH 7.2. This product is used as a blocking reagent or control for most immunoassay applications. Blocking is a critical step in most immunoassays and "fills-in" the unoccupied spaces of the solid phase that are not occupied by immobilized proteins. Without blocking antibodies would bind non-specifically wich in turn could lead to false signaling and /or background issues. How to choose blocking serum?If you use a secondary from donkey e.g. donkey anti-chicken HRP (or other lable) - your blocking serum should be also coming from donkey. Serum from a species primary antibody is coming from should not be used as this will compete for binding sites with secondary antibodies. In this example serum from chicken should not be used as blocking reagent.