The purified immunoglobulin (Ig) preparations are isolated from pooled normal serum by a proprietary fractionation method. The immunoglobulin preparations are supplied as a lyophilized powder. Purity levels are 97% IgG as analyzed by SDS-Page. These preparations are especially useful as a co-precipitant in RIA methods employing polyethylene glycol or ammonium sulfate precipitation steps, or as a protein stabilizer or blocker in a number of immunoassays. These preparations are also useful as IgG control solutions for biochemical analytical tests. Immunoglobulin preparations reconstitute to pH 7.2 Buffer: 0.01M Phosphate buffer in 0.15M NaClPurity by SDS Page: = 97%Solubility: For best results, reconstitute in distilled water or buffer of choice